JP2008067089A - Content distribution system, terminal equipment in the system, program for the equipment, and information management method by the equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a content distribution system capable of securing a sufficient storage area in the storage part of terminal equipment as the area for a second distribution system, even when the terminal equipment participates in the second distribution system, which distributes content data by streaming in a broadcasting form from a content distribution device to the terminal equipment, in a state where the terminal equipment participates in a first distribution system, where the other terminal equipment holding the content data distributes the content data, based on the download request of the content data from one terminal equipment, between several pieces of terminal equipment, and to provide the terminal equipment in the system, the program for the terminal equipment, and an information management method by the terminal equipment. <P>SOLUTION: When the terminal equipment participates in the second distribution system in a state where the equipment participates in the first distribution system, a part of the storage area to be secured for the first distribution system is functioned as the storage area for the second distribution system concerning the storage part of the terminal equipment. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a content distribution system, a terminal device in the system, a program for the terminal device, and an information management method using the terminal device.

  In recent years, a terminal device such as a personal computer is connected to an information communication network such as the Internet (hereinafter simply referred to as a “network”) to hold content data corresponding to desired content such as music or movies. 2. Description of the Related Art Content distribution systems that can receive content data from a server or another terminal device and can view the received content data on each terminal device are widely used.

  This type of content distribution system includes an on-demand content distribution system (hereinafter referred to as “content distribution system”) that distributes content data to a terminal device that has transmitted a download request from another terminal device that holds desired content data connected to a network. "First distribution system") and a broadcast-type content distribution system (hereinafter referred to as "first distribution system") that receives content data that has been distributed in a broadcast form from a content distribution apparatus on a network by connecting to the network. "Second delivery system").

  As this first distribution system, for example, a content distribution system in which a plurality of types of content data are distributed and held in a plurality of terminal devices connected to a network, and content data is exchanged between the terminal devices. Is known (see, for example, Patent Document 1).

  In order to download the desired content data by the first distribution system, the desired content data is identified from a plurality of types of content data existing on the network, and the desired content data is held on the network. It is necessary to identify other terminal devices that are present.

  Therefore, in the first distribution system, content identification information (hereinafter referred to as “content ID”) for identifying each content data is assigned to all the content data using a DHT (Distributed Hash Table). At the same time, terminal identification information (hereinafter referred to as “terminal ID”) for identifying each terminal device is assigned to all terminal devices, and a content ID related to predetermined content data and a terminal holding the content data Some terminal apparatuses (hereinafter referred to as “IP cache”) and information relating to the location of the apparatus (hereinafter referred to as “IP address”) and terminal ID (hereinafter referred to as “index cache information”). It is stored in a distributed manner on the “root terminal device”.

  At this time, the terminal device that is the root terminal device of certain content data has the largest number of information in each digit of the content ID assigned to the certain content data and information in each digit of the terminal ID continuously from the upper side. This is a terminal device to which a matching terminal ID (terminal ID closest to the content ID) is assigned.

  The index cache information stored in the root terminal device is information that is finally transferred to the root terminal device while being transferred to a plurality of terminal devices according to a predetermined rule from the terminal device that newly holds the content data. It is also stored in each terminal device corresponding to the transfer path. Each terminal device that transfers the index cache information transfers the index cache information according to a routing table that will be described later.

  Each terminal device includes a routing table in which other terminal information in which a part of the terminal IDs among all the terminal IDs is associated with an IP address that can be placed on the network of the terminal device corresponding to the terminal ID is recorded. ing.

  In this routing table, a terminal ID group (hereinafter referred to as “ID space”) including all terminal IDs is subdivided while increasing the number of levels for each stepped level, and the level (stepwise subdivision). For each area), other terminal information in which a terminal ID of an arbitrarily selected terminal device and its IP address are paired is stored.

  In other words, this terminal table stores other terminal information related to some terminal devices among all terminal devices.

  Each terminal device refers to this routing table when transmitting various information (messages) related to predetermined content data such as a content data download request and index cache information to the other terminal device. In the other terminal information stored in the terminal device, information is transmitted to the terminal device to which the terminal ID closest to the content ID of the predetermined content data is assigned, and the terminal device that has received this information has its own routing table. Similarly, the received information is transmitted (transferred) to other terminals, and the information is finally transferred to the root node.

  In the first distribution system configured as described above, each terminal device starts an application for participating in the first distribution system, connects to the network, and the storage unit included in each terminal device uses the first distribution system. A storage area is secured, and various information such as the above routing table, index cache information, catalog information including list information of currently downloadable content data, and the like are stored in the storage area for the first distribution system.

  When a terminal device intends to receive distribution of content data, the terminal device first holds desired content data by referring to the routing table stored in the storage area for the first distribution system. A predetermined message is transmitted to the root node in order to obtain information on the terminal device that is currently operating.

  As described above, this message is transferred to several terminal devices and received by the root node. Then, the root node that has received this message returns index cache information related to the content data that the terminal device is about to receive to the terminal device that is the source of the message.

  The terminal device that has received the index cache information refers to the received index cache information, and transmits the content download request to the terminal device that holds the desired content data, thereby distributing the desired content data. To receive.

  In addition, as the second distribution system, for example, content data distributed in a broadcast form from a content distribution device in which a plurality of terminal devices are logically connected in a tree-like hierarchical structure on a network with the content distribution device at the top. However, there is known a content distribution system in which streaming is sequentially performed by a relay function of each terminal device from a terminal device connected upstream of a tree-like hierarchical structure to a terminal device connected downstream (for example, Patent Document 2). reference.).

  That is, in this second distribution system, each terminal device participates in the second distribution system, starts an application, connects to the network, and has a storage area for the second distribution system in the storage unit included in each terminal device. Secure.

  When a terminal device intends to receive distribution of content data, the terminal device first participates in the second distribution system to the connection management device that manages the logical connection state of each terminal device in the hierarchical structure. The request is transmitted, and the IP address of the terminal device as the connection destination transmitted from the connection management device is received.

  Thereafter, the terminal device that has received this IP address connects to the downstream side in the hierarchical structure of the terminal device corresponding to the received IP address, and receives desired content data from the upstream terminal device in the hierarchical structure.

  At this time, the terminal device causes the storage area for the second distribution system to function as a ring buffer, and temporarily stores the content data stream-received from the upstream terminal device in the hierarchical structure in the ring buffer. The content data stored in the buffer is sequentially played back, and the content data of the part that has been played back is deleted from the ring buffer.

Also, in the hierarchical structure, when another terminal device is connected to the downstream side in the hierarchical structure of this terminal device, the reproduced content data is connected to the downstream side in the hierarchical structure before being deleted from the ring buffer. It is relayed to other terminal devices (streaming distribution) and then deleted from the ring buffer.
JP 2006-197400 A JP 2006-087046 A

  However, in the conventional terminal device, as described above, when participating in the first distribution system, a storage area for the first distribution system is secured in the storage unit of the terminal device, and when participating in the second distribution system. In order to secure a storage area for the second distribution system in the storage unit of the terminal device, when participating in the second distribution system while participating in the first distribution system, the storage area for the second distribution system is There is a problem that the second delivery system may interfere with streaming reception of content data without being sufficiently secured.

  That is, when the terminal device is participating in the first distribution system, it is necessary to store various information such as index cache information, catalog information, and a routing table. As a result, a relatively large storage area must be secured.

  Therefore, if a relatively large storage area is secured as the storage area for the first distribution system in this way and it is attempted to participate in the second distribution system, a sufficient ring buffer area is secured for the second distribution system. There is a risk that content data cannot be received, played back, relayed, etc. normally.

  In addition, in order to be able to participate in the second distribution system at any time, it may be possible to secure a storage area for the second distribution system in the storage unit in advance, but in this case, when not participating in the second distribution system Since the storage area is secured uselessly, there is a problem in that a storage unit with a limited capacity cannot be used effectively.

  Therefore, the present invention has been made in view of the above-described problems, and the purpose thereof is as described above, even if it participates in the second distribution system in the state where it participates in the first distribution system. Content distribution system capable of sufficiently securing a ring buffer area used in the second distribution system in the section and effectively using the storage section, a terminal device in the system, a program of the terminal device, and the terminal device It is to provide an information management method according to.

  According to the first aspect of the present invention, in a first distribution system in which another terminal device that holds content data based on a content data download request from one terminal device distributes the content data among a plurality of terminal devices. In a participating state, a terminal device capable of participating in a second distribution system that performs streaming distribution of content data from a content distribution device to a terminal device in a broadcast form, when participating in the first distribution system, A storage area reserved for the distribution system and a part of the storage area reserved for the first distribution system when participating in the second distribution system while participating in the first distribution system. And an information management unit that functions as a storage area for the system.

  According to a second aspect of the present invention, the terminal device according to the first aspect further comprises a storage capacity detecting means for detecting a capacity of a storage area required by participating in the second distribution system, and an information management means. Determining whether or not to make a part of the storage area reserved for the first distribution system function as the storage area for the second distribution system according to the detection result of the storage capacity detection means. To do.

  According to the third aspect of the present invention, in the terminal device according to the first or second aspect, the first distribution system has a plurality of types of content data stored in a plurality of terminal devices connected via a network. A distribution system in which content data is distributed from another terminal device that holds content data corresponding to a download request to a terminal device that has transmitted the download request. The content holding terminal information that associates the location information of the other terminal device that is participating and holding the content data and the content identification information for identifying the content data held by the other terminal device is received. Content holding terminal information receiving means, and the information management means stores content in a storage area reserved for the first distribution system. The content holding terminal information received by the holding terminal information receiving means is stored and stored in a storage area reserved for the first distribution system when participating in the second distribution system while participating in the first distribution system. The content holding terminal information is deleted, and the area storing the content holding terminal information is caused to function as a storage area for the second distribution system.

  Moreover, in this invention which concerns on Claim 4, in the terminal device of Claim 3, the content holding terminal information which the terminal device manages from the terminal device which manages the said content holding terminal information of deletion object A storage area reserved for the first distribution system when the information amount acquired by the information amount acquisition unit exceeds a predetermined threshold value. And deleting the content holding terminal information to be deleted.

  Further, in the present invention according to claim 5, in the terminal device according to claim 4, the information management means acquires and acquires the information amount of the content holding terminal information related to the plurality of types of content data by the information amount acquisition means. Of the plurality of types of information amounts, the content holding terminal information with a large amount of information is deleted in order.

  Further, in the present invention according to claim 6, in the terminal device according to any one of claims 1 to 5, the information management means is a content that is currently downloadable in a storage area reserved for the first distribution system. When list information of data is stored, and when participating in the second distribution system in a state of participating in the first distribution system, the list information is deleted from the storage area reserved for the first distribution system, and the list information is stored. The stored area is made to function as a storage area for the second distribution system.

  Moreover, in this invention which concerns on Claim 7, in the terminal device of any one of Claims 1-6, an information management means puts another terminal device in the storage area ensured for 1st delivery systems. Other terminal information including terminal identification information for identification and location information of other terminal devices is stored, and when participating in the second distribution system in a state of participating in the first distribution system, for the first distribution system It is characterized in that at least a part of the other terminal information is deleted from the reserved storage area, and the area in which the other terminal information is stored functions as a storage area for the second distribution system.

  In the present invention according to claim 8, in the terminal device according to claim 1 or claim 2, the information management means participates in the first distribution system in the storage area reserved for the first distribution system. Content holding terminal information that associates location information of other terminal devices holding content data with content identification information for identifying content data held by other terminal devices, and is currently available for download The content data list information is stored, and the terminal identification information for identifying other terminal devices and the other terminal information including the location information of the other terminal devices are stored and participated in the first distribution system. If the content holding terminal information and the list information are deleted from the storage area reserved for the first distribution system when participating in the second distribution system in the state, , And deletes a part of the other terminal information.

  In the present invention according to claim 9, in the terminal device according to claim 8, in the information stored in the storage area reserved for the first distribution system, the priority of deletion by the information management means is the content The holding terminal information, list information, and other terminal information are in this order.

  Further, in the present invention according to claim 10, in the terminal device according to any one of claims 1 to 9, there is provided a participation terminal number detection means for detecting the number of terminal devices participating in the first distribution system. When the number of terminal devices detected by the participating terminal number detection unit exceeds a predetermined threshold, the information management unit uses a part of the storage area reserved for the first distribution system for the second distribution system. It is characterized by functioning as a storage area.

  Moreover, in this invention which concerns on Claim 11, in the terminal device of any one of Claims 1-10, in order to preserve | save the information deleted from the storage area ensured for 1st delivery systems When the second distribution system is joined in a state in which the other distribution means is provided and participates in the first distribution system, the information management means stores part of the information stored in the first distribution system as another storage means. The information stored in the other storage means after functioning as the storage area for the second distribution system after being saved in the other storage means, and the information stored in the other storage means after leaving the second distribution system Is again stored in the storage area reserved for the first distribution system.

In the present invention according to claim 12,
The storage area reserved for the second distribution system includes a ring buffer for temporarily storing content data stream-received by the second distribution system,
In the terminal device according to any one of claims 1 to 11, the information management unit is reserved for the first distribution system when participating in the second distribution system while participating in the first distribution system. A part of the storage area is made to function as a ring buffer.

  Moreover, in this invention which concerns on Claim 13, in the terminal device of any one of Claims 1-12, the receiving speed detection means which detects the receiving speed at the time of receiving content data by a 2nd delivery system is provided. The information management means reserves for the first distribution system according to the reception speed acquired by the reception speed detection means when participating in the second distribution system in the state of participating in the first distribution system. Of the storage areas, an area that functions as a storage area for the second distribution system is expanded or reduced.

  According to the fourteenth aspect of the present invention, the first distribution in which another terminal device that holds content data based on a request for downloading content data from one terminal device distributes the content data among a plurality of terminal devices. A content distribution system having a system and a second distribution system for streaming distribution of content data from the content distribution apparatus to the terminal device in a broadcast form, when the terminal device participates in the first distribution system, A storage area reserved for the first distribution system and a part of the storage area reserved for the first distribution system when participating in the second distribution system in the state of participating in the first distribution system A content distribution system comprising: information management means that functions as a storage area for the distribution system.

  According to a fifteenth aspect of the present invention, there is provided a program for causing a computer to function as each means in the terminal device according to any one of the first to thirteenth aspects.

  According to the sixteenth aspect of the present invention, the first distribution in which another terminal device that holds content data based on a request for downloading content data from one terminal device distributes the content data among a plurality of terminal devices. An information management method in a terminal device capable of participating in a second distribution system that performs streaming distribution of content data from a content distribution device to a terminal device in a broadcast form while participating in the system, A storage area reserved for the first distribution system when participating in the second distribution system in a state of participating in the first distribution system, and a step of securing a storage area for the first distribution system. A step of deleting a part of the stored information, and securing for the first distribution system in which the deleted information was stored The storage area, and having a step function as a storage area for the second distribution system, the.

  According to this invention of Claim 1 and Claims 14-16, when participating in a 2nd delivery system in the state which has participated in the 1st delivery system, in a memory | storage part of a terminal device, the 1st delivery By making a part of the storage area reserved for the system function as a storage area for the second distribution system, a sufficient storage area for the second distribution system can be secured. Since there is no hindrance to streaming reception of content data and it is not necessary to secure a storage area for the second distribution system in the storage unit in advance when not participating in the second distribution system, The storage unit can be used effectively.

  According to the second aspect of the present invention, the information management means is provided for the first distribution system when there is a free area in the storage unit of the terminal device that can sufficiently secure a storage area for the second distribution system. Since it is not necessary to perform processing for causing the storage area to function as a storage area for the second distribution system, the processing load on the information management means can be reduced accordingly.

  According to the present invention described in claims 3 and 6 to 8, information that does not hinder the reception of content data by the first distribution system is deleted even if deleted, and the storage area in which the deleted information is stored Can function as a storage area for the second distribution system, so that a sufficient storage area can be secured as a storage area for the second distribution system while participating in the first distribution system.

  According to the present invention described in claims 4 and 5, there is no problem in receiving data in the first distribution system.

  According to the ninth aspect of the present invention, in the storage area for the first distribution system, when content data is received by the first distribution system, information that is less likely to cause trouble can be deleted in order. .

  According to the tenth aspect of the present invention, since the other terminal device that needs the information held by itself can be acquired from the other terminal devices participating in the first distribution system, Even if the information stored in the storage area for the first distribution system is deleted, other terminal devices participating in the first distribution system are not hindered.

  According to the present invention as set forth in claim 11, when the information deleted from the storage area for the first distribution system becomes necessary again, the information stored in the other storage means is newly stored for the first distribution system. Since it can be stored in the area, it does not hinder the reception of content by the first distribution system.

  According to the present invention as set forth in claim 12, since a sufficient storage area can be secured as a ring buffer used in the second distribution system, even if it is in a state of participating in the first distribution system, 2. Content data reception and content data relay by the distribution system can be reliably performed.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings. The embodiment described below is an embodiment when the present invention is applied to a content distribution system in which information to be distributed is content data such as music data and video data.

[Content distribution system configuration]
The content distribution system according to the present embodiment is a first distribution in which another terminal device that holds content data distributes the content data among a plurality of terminal devices based on a content data download request from one terminal device. And a second distribution system that distributes the content data from the content distribution apparatus to the terminal device in a broadcast form.

  And the terminal device in this embodiment is comprised so that it can participate in the said 2nd delivery system in the state which has participated in the said 1st delivery system.

  In this embodiment, there are various content distribution systems that transmit and receive content data between a plurality of terminal devices as an example of the first distribution system. In the present embodiment, the P2P grid distribution system is particularly distributed hash. A content distribution system that transmits and receives content data between terminal devices by using a table (DHT (Distributed Hash Table)) will be described as an example of a content distribution system called a Pastry type.

  In addition, examples of the second distribution system include a server-client type broadcast form and a broadcast form with a tree-like hierarchical structure. In this embodiment, content data streamed from a content distribution apparatus is represented by a tree. A content distribution system in a broadcast form that is received and relayed by P2P by a terminal device that forms a hierarchical structure will be described as an example.

  FIG. 1 is a diagram illustrating a schematic configuration example of a content distribution system S according to the present embodiment. As in the physical connection form shown in FIG. 1, the content distribution device 1, the terminal devices 2a1, 2a2, 2b1 to 2b4, 2c1 to 2c8, the connection management device 3, the content input device 4, and the contact destination introduction constituting the content distribution system S The devices 5 are distributed on a network 6 represented by the Internet.

  The content distribution device 1, terminal devices 2 a 1, 2 a 2, 2 b 1 to 2 b 4, 2 c 1 to 2 c 8, connection management device 3, content input device 4, contact destination introduction device 5 have terminal identification information (hereinafter referred to as “terminal” A unique manufacturing number (for example, a MAC address) and an IP (Internet Protocol) address (location information) are assigned as IDs), and these devices are connected to the network 6 via the router 10 or the like. Yes. Then, communication connection is possible by transmitting a packet including a header in which the IP address of the target connection destination device is the destination IP address and the IP address of the own device is the source IP address.

  An apparatus not directly related to the content distribution system S is also connected to the network 6, but is omitted here. Further, in the case of showing any one of the terminal devices 2a1, 2a2, 2b1-2b4, 2c1-2c8 or all the terminal devices, it may be called the terminal device 2 for convenience.

  In the example shown in FIG. 1, the content distribution device 1, the connection management device 3, the content input device 4, and the contact destination introduction device 5 are independent devices, but the functions of these devices are realized in one device. It may be. In this case, the IP addresses of these devices are the same and are distinguished by port numbers and the like.

[1.1. About the first distribution system]
Next, with reference to FIG. 2, a schematic configuration and the like of the first distribution system in the content distribution system S will be described. FIG. 2 is a diagram illustrating a first distribution system in the content distribution system S according to the present embodiment. The first distribution system is a P2P grid type distribution system, and a plurality of terminal devices 2 distributed on the network 6 by using a distributed hash table (hereinafter referred to as “DHT”). It is a content distribution system that transmits and receives content data between.

[1.1.1 Outline of DHT]
First, an algorithm using DHT according to the present embodiment will be described.

  In the first distribution system of the content distribution system S, when the terminal devices 2 exchange information with each other, they must know the IP addresses as the location information of each other.

  For example, in a system in which content data is shared among a plurality of terminal devices, each terminal device 2 participating in the network 6 knows the IP addresses of all the terminal devices 2 participating in the network 6. However, when the number of terminals becomes as large as tens of thousands, it is not realistic to remember the IP addresses of all the terminal devices 2. Further, if the power supply of an arbitrary terminal device is frequently turned on or off, the IP address of the arbitrary terminal device stored in each terminal device 2 is frequently updated, which makes operation difficult.

  Therefore, one terminal device 2 stores only the IP addresses of some of the minimum necessary terminal devices 2 among all the terminal devices 2 participating in the network 6, and stores the IP addresses. For terminal devices 2 that are not connected, a system for delivering content data by transferring information between the terminal devices 2 has been devised.

  As an example of such a system, an overlay network as shown in FIG. 2 is constructed by an algorithm using DHT. That is, this overlay network means a network that forms a virtual link (logical connection) formed using the existing network 6.

  In this embodiment, it is assumed that the overlay network is constructed by an algorithm using DHT, and the terminal device 2 arranged on this overlay network is a terminal participating in the first distribution system of the content distribution system S. It is called device 2.

  A unique number (unique number) is assigned to each terminal device 2 as a terminal ID that is terminal identification information for identifying each terminal device 2 participating in the first distribution system of the content distribution system S. This number needs to have a number of bits that can accommodate the maximum number of operating terminal devices. For example, if a 128-bit number is used, 2128≈340 × 1036 terminal devices can be operated.

  More specifically, the terminal ID of each terminal device 2 is obtained by hashing a unique value for each terminal device 2 such as the IP address or manufacturing number of each terminal device 2 with a common hash function (hash algorithm). The obtained hash value is distributed and arranged in one ID space without deviation. Thus, the terminal ID obtained by hashing with a common hash function has a very low probability of having the same value if the IP address or the manufacturing number is different. Since the hash function is publicly known, detailed description thereof is omitted. In the present embodiment, a value obtained by hashing an IP address (global IP address) with a common hash function is used as a terminal ID.

  In addition, as shown in FIG. 2, content data distributed from one terminal device 2 to another terminal device 2 includes content in a plurality of terminal devices 2 participating in the first distribution system of the content distribution system S. The content is distributed by the input device 4 and input to the terminal device 2. In order to identify each content data, the content data also has unique content identification information (hereinafter referred to as “content ID”). Call).

  The content ID has the same length as the terminal ID (for example, 128 bits). For example, when a keyword such as a content name (content title) or content outline information (summary) obtains the terminal ID And the terminal ID closest to the hash value (for example, the higher-order digits match more) are hashed by a common hash function (that is, placed in the same ID space as the hash value of the IP address of the terminal device 2). The terminal device 2 possessed holds the link information to the terminal device 2 that holds the content data (hereinafter referred to as “content holding terminal device”), that is, the IP address that is the location information of the content holding terminal device.

  The content holding terminal device is randomly determined by the content input device 4. That is, the content input device 4 randomly determines one or more terminal devices 2 that should hold the content data, and transmits the content data to the terminal device 2 determined in this way. The terminal device 2 that has received the content data from the content input device 4 functions as a content holding terminal device by holding the content data in the storage unit. Thereby, the content data is distributed and arranged on the content distribution system S without any bias.

  Note that even if the content data is different, it is assumed that the same keyword (for example, the name of the content) is used. In this case, the hash value is the same to avoid the same hash value. The keyword may be, for example, a combination of content title and copyright information (for example, performer name, director name, original author name, singer name, composer name, or songwriter name). In the present embodiment, it is assumed that content titles do not overlap and the content title is a keyword.

  As described above, since the terminal ID and the content ID assigned to each terminal device 2 and each content data are generated by a common hash function, as shown in FIG. 2, the terminal ID and the content ID are slightly biased on the same ring-shaped ID space. It can be thought of as being scattered and present. This figure shows a terminal ID and content ID assigned in 32 bits. In the figure, a round dot indicates a terminal ID, a square indicates a content ID, and the ID increases counterclockwise.

  Next, which content data is managed by which terminal device 2 is determined under a certain rule. In the present embodiment, the rule is that “the terminal device 2 that manages content data having a certain content ID is a terminal device 2 having a terminal ID close to that content ID”.

  Here, the definition of “close” does not exceed the content ID, and the difference between the content ID and the terminal ID is the smallest. However, in practice, the management of each content data is assigned to each terminal device 2. It is only necessary to be consistent when allocating. In the example shown in FIG. 2, based on this definition, the content IDa is managed by the terminal device 2 having a terminal ID close to the content IDa (hereinafter referred to as “terminal IDa”), and the content IDb is the content IDb. Managed by the terminal device 2 having a terminal ID close to IDb (hereinafter referred to as “terminal IDb”), and the content IDc has a terminal ID close to the content IDc (hereinafter referred to as “terminal IDc”). Managed by the device 2.

  Here, “management” does not mean that content data is held, but “knows which terminal device 2 holds the content data”. That is, in FIG. 2, the terminal device 2 having the terminal IDa knows which terminal device 2 holds the content data having the content IDa, and the terminal device 2 having the terminal IDb and the terminal having the terminal IDc. Similarly, the device 2 knows which terminal device 2 holds the content data having the content IDb and the content data having the content IDc.

  In this way, the terminal device 2 that knows which terminal device 2 holds certain content data is called the root terminal device of the content data, and this root terminal device itself becomes the root terminal device. The content holding terminal information associating the content ID of the content data being held with the IP address of the content holding terminal device holding the content data is held more than the other terminal devices.

  In FIG. 2, the terminal device 2 having the terminal IDa is a content data root terminal device having the content IDa, and the terminal device 2 having the terminal IDb is a content data root terminal device having the content IDb. The terminal device 2 having the terminal IDc is the root terminal device for content data having the content IDc.

  Here, the content input device 4 has the function of distributing content data to the terminal device 2 in order to make the terminal device 2 in the content distribution system S a content holding terminal device, as well as the current first distribution distributed to the terminal device 2. A plurality of content data that can be downloaded by the system (in other words, content data held by the content holding terminal device) is generated to generate catalog information including list information in which the content title and content ID are associated with each other. It has a function to be provided to the terminal device 2.

  Further, in the first distribution system of the content distribution system S, the contact destination introduction device 5 is arranged. The contact introduction device 5 is configured so that when a terminal device 2 not participating in the first distribution system of the content distribution system S has requested to participate in the first distribution system, the non-participating terminal device 2 receives a participation message. Has the function of notifying the location information of the terminal device 2 that has already participated (hereinafter referred to as “contact destination terminal device”).

[1.1.2. Create routing table]
Next, an example of a method for creating a routing table used in DHT and the configuration of the created routing table will be described with reference to FIGS.

  Here, the terminal device 2 of the present embodiment, as a routing table, transmits a main table MR that is mainly used when transmitting information or the like to the other terminal devices 2, and a sub-table that is sequentially used as an alternative to the main table MR. A routing table RT including a plurality of tables R1 to R3 is provided.

  FIG. 3 is a diagram illustrating an example of a state in which a routing table is created by DHT, FIG. 4 is an explanatory diagram illustrating a configuration of the main table MR, and FIG. 5 is a diagram illustrating the main table MR and the sub tables R1 to R3. It is explanatory drawing which shows the whole structure of the routing table RT comprised by these.

  In the terminal device 2 of this embodiment, when creating the routing table RT, first, the main table MR is created as follows.

  That is, as shown in FIG. 3A, the ID space is divided into several areas. Actually, about 16 divisions are often used, but in order to simplify the explanation, four divisions are used here, and the ID is represented by a quaternary number having a bit length of 8 bits. An example in which the terminal ID of the terminal device 2N is “1133” and the main table MR of the terminal device 2N is created will be described.

(Level 1 routing)
First, if the ID space is divided into four areas, each area is represented by four areas “0XXX”, “1XXX”, “2XXX”, “3XXX” (X is a natural number from 0 to 3, The same shall apply hereinafter.) Since the terminal ID of the terminal device 2N itself is “1133”, the terminal device 2N exists in the lower left “1XXX” area in FIG. The terminal device 2N is a terminal device existing in an area (that is, an area of “0XXX”, an area of “2XXX”, an area of “3XXX”) other than the area where the terminal device exists (that is, the area of “1XXX”). 2 is selected at random, and the location information of the terminal ID, that is, the IP address of the terminal ID is stored in the level 1 table. FIG. 4 is an example of a level 1 table. In this table, “0100” is selected as the terminal ID of the “0XXX” area, “2133” is selected as the terminal ID of the “2XXX” area, and “3213” is selected as the terminal ID of the “3XXX” area. Show. Since the second column of level 1 indicates the terminal device 2N itself, it is not necessary to store the IP address.

(Level 2 routing)
Next, as shown in FIG. 3B, among the areas divided into four by the above routing, the area “1XXX” where the user exists is further divided into four, and four areas “10XX”, “11XX”, and “12XX” are further divided. , “13XX”. Similarly to the above, the terminal device 2 existing in an area other than the area “11xx” in which it is present is randomly selected, and the IP address that is the location information of the terminal ID is stored in the level 2 table. FIG. 4 is an example of a level 2 table. In this table, “1003” is selected as the terminal ID of the “10XX” area, “1221” is selected as the terminal ID of the “12XX” area, and “1313” is selected as the terminal ID of the “13XX” area. Is shown. The second column of level 2 is an area “11XX” in which the terminal device 2N exists, and since it is tabulated at level 3 to be described later, no IP address is stored. When the terminal device 2 does not exist in the area, the terminal ID and IP address fields are blank.

(Level 3 routing)
Further, of the areas divided into four by the above routing, the area “11XX” where the user exists is further divided into four, and further divided into four areas “110X”, “111X”, “112X”, and “113X”. Similarly to the above, the terminal device 2 existing in an area other than the area “113X” in which it is present is randomly selected, and the IP address that is the location information of the terminal ID is stored in the level 3 table. FIG. 4 is an example of a level 3 table. The fourth column of level 3 is an area where the terminal device 2N exists, and since it is tabulated at level 4 described later, no IP address is stored. If there is no terminal device in the area, the terminal ID and IP address fields are blank.

  In this way, all the 8-bit IDs can be covered by creating the main table MR as shown in FIG. As the level goes up, white space becomes more noticeable in the table.

  Then, the terminal device 2 creates the sub tables R1 to R3 in the same manner as the creation of the main table MR, and creates the routing table RT having the configuration shown in FIG.

  In this configuration, the main table MR includes a total of 16 entries (four levels × four areas) for four levels from level 1 to level 4. The sub-table R1 includes a total of eight entries (two levels × four areas) corresponding to two levels 1 and 2, and each of the sub-tables R2 and R3 includes only level 1s. Four entries E (one level × four areas) are included. That is, as the routing table RT, the number of levels in each table is decreased exponentially as viewed from the main table MR.

  In each entry E, in addition to other terminal information including a terminal ID and an IP address indicating the terminal device 2 of the corresponding level routing destination (transfer destination), a message or the like is sent to the terminal device 2 of the routing destination. The number of hops, which is the number of terminal devices 2 that are relayed before reaching, is the distance on the network to the routing destination terminal device 2 (in other words, when a message or the like reaches the routing destination terminal device 2). Is described as information indicating the ease of The terminal ID, IP address, etc. and the number of hops are collectively referred to as “node information” hereinafter.

  Further, in the main table MR and sub-tables R1 to R3 constituting the routing table RT, the entry E corresponding to the same level and the same area in each table contains the terminal device 2 that can be a transfer destination belonging to the same area. Node information is described in the main table MR and the sub-tables R1 to R3 in order from the terminal device 2 with the smallest number of hops for one terminal device 2 each.

  More specifically, for example, when attention is paid to the entry ME1 of the main table MR illustrated in FIG. 5, another one terminal belonging to the same area as the terminal device 2 indicated by the node information described in the entry ME1. Node information indicating the device 2 is described in the entry R1E1 of the subtable R1, the entry R2E1 of the subtable R2, and the entry R3E1 of the subtable R3 corresponding to the same level and the same area as the entry ME1.

  The number of hops to the terminal device 2 indicated by the terminal ID described in the entry ME1 of the main table MR is the number of hops to the terminal device 2 indicated by the terminal ID described in the entry R1E1 of the subtable R1. The number of hops to the terminal device 2 indicated by the terminal ID described in the entry R1E1 is smaller than the number of hops, and the number of hops to the terminal device 2 indicated by the terminal ID described in the entry R2E1 of the sub-table R2 The number of hops to the terminal device 2 indicated by the terminal ID described in the entry R2E1 is less than the number of hops up to the terminal device 2 indicated by the terminal ID described in the entry R3E1 of the sub-table R3. The number of hops is less.

  In the routing table RT shown in FIG. 5, the number of hops to the terminal device 2 indicated by the terminal IDs described in the entries ME1, R1E1, R2E1, and R3E1 can be configured to be equal to each other. In this case, the terminal ID indicating the terminal device 2 having the latest time when the message is received from the other terminal device 2 is described in the entry ME1.

  When a message or the like is transmitted (transferred) to another terminal device 2 using the routing table RT having such a configuration, for example, the terminal device 2 indicated by the terminal ID described in the entry ME1 of the main table MR. However, when it is recognized that the terminal device 2 itself no longer exists in the first distribution system because, for example, the terminal device 2 itself has left the first distribution system, a new search is made for the terminal device 2 that is another routing destination. Without this, the other terminal device 2 (in the same area) indicated by the node information described in the entry R1E1 of the sub-table R1 is immediately switched to a new routing destination and the necessary DHT routing processing is continued.

  In transmission of a message or the like using the other terminal device 2 as a routing destination, the node information originally described in the entry R1E1 is rewritten in the entry ME1 and the node information originally described in the entry R2E1 is entered. The routing table RT is rewritten in the R1E1 and the node information originally written in the entry R3E1 is rewritten in the entry R2E1 to prepare for transmission of a new message or the like.

  Further, for example, when another terminal device 2 in the same level and the same area having a smaller number of hops than the terminal device 2 indicated by the terminal ID currently described in the entry ME1 is found, the newly discovered one is found. The node information indicating the terminal device 2 is newly described in the entry ME1, the node information originally described in the entry ME1 is rewritten in the entry R1E1, and the node information originally described in the entry R1E1 is rewritten in the entry R2E1. In addition, the routing table RT for rewriting the node information originally described in the entry R2E1 into the entry R3E1 is updated to prepare for transmission of a new message or the like.

  All the terminal devices 2 each create and hold the routing table RT described above. Thus, each terminal device 2 is a routing table that associates terminal IDs (terminal identification information), IP addresses (location information), and the like of some of the terminal devices 2 among the plurality of terminal devices 2 in the first distribution system. RT is included, and this routing table RT is stored in a first distribution system storage area 250 (see FIG. 14), which will be described later.

  By the way, the terminal device 2 of the present embodiment does not know the location information of other terminal devices 2 participating in the first distribution system when not participating in the first distribution system. Therefore, when the terminal device 2 participates in the first distribution system, the terminal device 2 generates a routing table as described in the next section.

  Note that the terminal device 2 of the present embodiment is configured to start an application for participating in (connecting to) the first distribution system at the same time as the power is turned on, and while the power is turned on, It is comprised so that the state which has always participated in the 1st delivery system may be maintained.

[1.1.3. Participation in the first distribution system]
Next, referring to FIG. 6, a method in which power is applied to the terminal device 2 that has not participated in the first distribution system in the content distribution system S (the power is not turned on) and participates in the first distribution system. An example will be described. FIG. 6 is a diagram illustrating an example of a state in which a terminal device 2 that has not participated in the first distribution system (hereinafter referred to as “new participation terminal device 2M”) participates in the first distribution system. Here, a procedure in which the newly participating terminal device 2M participates in the first distribution system in the content distribution system S will be described.

  First, the new participation terminal apparatus 2M that has not participated in the first distribution system starts an application for participating in the first distribution system when the power is turned on, and the main part described later included in the new participation terminal apparatus 2M. The first distribution system storage unit 205b (see FIGS. 13 and 14) in the storage device 205 is used in the first distribution system such as the routing table RT and the index table 222 described later. A storage area for the first distribution system is secured as an area for storing various types of information.

  Thereafter, in order to participate in the first distribution system of the content distribution system S, the new participation terminal apparatus 2M should transmit a participation message to the contact introduction apparatus 5 (hereinafter referred to as “contact terminal apparatus”). Requesting location information (hereinafter referred to as “inquiry of a contact terminal device”).

  The new participation terminal device 2M transmits a participation message to the contact destination terminal device when the location information of the contact destination terminal device to which the participation message is to be transmitted is sent from the contact destination introduction device 5. Here, the destination identification information of the participation message is the terminal ID of the new participation terminal device 2M. That is, the new participation terminal apparatus 2M generates a participation message using the hash value “2133” of the IP address of the own apparatus 2 as destination identification information when participating in the first distribution system.

  When the contact destination terminal device receives the participation message transmitted from the new participation terminal device 2M, the contact destination terminal device determines whether or not the participation message is a message addressed to the contact destination terminal device. Whether the message is addressed to the contact destination terminal device is determined based on the destination identification information and the routing table RT. Specifically, it is determined whether the destination identification information is close to the identification information addressed to the contact destination terminal device. That is, for the destination identification information, is the terminal ID of the terminal device 2 that is closest to the terminal ID of the terminal device 2 stored in the routing table RT held by the contact destination terminal device itself? It is determined whether it is another terminal device 2.

  When the terminal ID of the other terminal device is closer to the destination identification information than the terminal ID of the contact destination terminal device, the contact destination terminal device that has received the participation message has the routing held by the contact destination terminal device itself. Referring to level 2 of table RT, among the terminal devices 2 belonging to the area “2XXX”, the participation message is transferred to the terminal device 2B that knows the IP address and is held by the own terminal device 2 Information on the level 1 table of the routing table is transmitted to the newly participating terminal apparatus 2M.

  In this way, the participation message is transferred in the manner of adapting the digits of the content ID in order from the top, and information on each level of the routing table RT is sequentially transmitted. When the terminal device 2 that finally comes closest to the destination identification information is reached, the transfer of the participation message ends. A mechanism for transferring a message such as a participation message to the target terminal device 2 as described above is called DHT routing.

  In this way, the new participation terminal device 2M obtains information of each level of the routing table RT from the higher level information in order from the terminal device 2 that has received the participation message. In this way, the new participation terminal 2 generates the routing table RT necessary for participating in the first distribution system.

[1.1.4. Content data search method]
Next, an example of a search method for the terminal device 2 that holds content data will be described with reference to FIG. FIG. 7 is a diagram illustrating an example of a state in which the terminal device 2 holding content data is searched by DHT routing.

  Here, a procedure when the terminal device 2N having the terminal ID “1133” searches for content data having the content ID “3020” will be described. Hereinafter, a terminal device that searches for content data and requests reception of content data in this way is referred to as a “request terminal device”.

  The requesting terminal device 2N refers to the level 1 table of the routing table RT held by itself and holds the content of the terminal ID of the terminal device having the terminal ID in the same area as the content ID “3020” as the destination identification information. A transmission request (hereinafter referred to as “content search message”) of terminal information (information including location information of the content holding terminal device) is transmitted. That is, since the content ID “3020” is an area of “3XXX”, the terminal device 2 belonging to the area of “3XXX” knows the IP address (that is, in the routing table RT held by itself). A content search message is transmitted to the terminal device 2A (terminal ID “3213”) in which the IP address is stored. Thus, the content search message includes a content ID that is unique identification information corresponding to the content, and this content ID is used as destination identification information in the content search message.

  According to the example shown in FIG. 7, since the IP address of the terminal device 2A whose terminal ID is “3213” is stored in the routing table (see FIG. 4) of the request terminal device 2N, the request terminal device 2N A content search message is transmitted to the terminal device 2A whose terminal ID is “3213”.

  Next, the terminal device 2A that has received the content search message determines whether or not the content search message is a message addressed to the terminal device 2A. Whether the message is addressed to the terminal device 2A is determined based on the destination identification information and the routing table RT. Specifically, it is determined whether the destination identification information is close to the terminal ID of the terminal device 2A. That is, for the destination identification information, whether the terminal ID of the terminal device 2 that is closest to the terminal ID of the terminal device 2 stored in the routing table RT held by the terminal device 2A itself is itself. It is determined whether it is a terminal device 2. Here, since the terminal ID of the other terminal device 2 is closer to the destination identification information than the terminal ID of its own terminal device 2A, the terminal device 2A has the routing table RT held by the terminal device 2A itself. Referring to the level 2 table, the content search message is transferred to the terminal device 2B (terminal ID “3031”) that knows the IP address among the terminal devices 2 belonging to the area “30XX”.

  In this way, the transfer of the content search message proceeds in the manner of adapting the digits of the content ID in order from the top, and finally the terminal device 2C (terminal ID “3011”) that manages the content data, that is, the root terminal device When the route terminal device arrives, the root terminal device searches the content ID “3020” included in the content search message from index cache information (described later) managed by itself, and owns the content data. The IP address or the like of the holding terminal device is returned to the request terminal device 2N.

  In this way, the request terminal device 2N receives the content holding terminal information (location information of the content data with the content ID “3020”, that is, the content data with the content ID “3020”) from the root terminal device 2C. IP address) is received, and the content data is downloaded and acquired from the content holding terminal device that has received the download request by transmitting a download request for the desired content to the content holding terminal device. Will do.

[1.1.5. How to register in the index table]
In the first distribution system in the content distribution system S, a method for publishing new content data so as to be visible to other terminal devices 2 on the network 6 will be described.

  As shown in FIG. 8, the first distribution system of the content distribution system S in this embodiment is a management target for each content holding terminal device with respect to the terminal device 2 in which the content input device 4 is each content holding terminal device. Send content data as content. The content holding terminal device that has received the content data to be managed from the content input device 4 stores the received content data in the hard disk device 203 (see FIG. 13) described later.

  As shown in FIGS. 8 and 9, the content holding terminal device to which the content data has been distributed is a content holding terminal information registration request message (hereinafter referred to as “content registration”) including the IP address and terminal ID of the content holding terminal device. Message ") is transmitted to the terminal device 2 having the same terminal ID as the content ID obtained from the content name or the like (whether or not this terminal device 2 actually exists is not known at this time). This content registration message is also transferred one after another according to the routing table RT in the same manner as the content search message, and is transferred to the terminal device 2 having the terminal ID closest to the content ID included in the content registration message. By the way, when the terminal device 2 determines that there is no other destination terminal device 2, the terminal device 2 itself determines that it should be the root terminal device of the content, and as shown in FIG. The content ID that is the content holding terminal information included in the content registration message, the IP address of the content holding terminal device, and auxiliary information (attribute information such as title, genre, and extended information, copyright information such as a director name, and streaming time Etc.) as index cache information. DEX is stored in the table 222 (see FIG. 13.).

  Thus, when the IP address, which is the location information of the content holding terminal device, is registered in the index table 222 of the root terminal device, the content holding terminal device registered in the index table in response to the content search message from the requesting terminal device thereafter. The location information is returned to the requesting terminal device. In this way, in the present embodiment, the content distributed from the content input device 4 is registered in the content holding terminal device, and can be searched via the root terminal device, so that the content is disclosed to other terminal devices. .

  As shown in FIG. 10, the index table 222 is a table for storing content holding terminal information including a content ID and an IP address that is location information (location information) of the content holding terminal device. The index table 222 stores the content ID, the IP address of the content holding terminal device, the time when the content holding terminal device was introduced, and the like as content holding terminal information for each row (predetermined storage area).

  In the present embodiment, when the content holding terminal information is transferred from the content holding terminal device to the root terminal device, each terminal device 2 existing on the transfer path (the terminal device that transferred the content holding terminal information) The index table 222 of 2) is also stored as index cache information.

[1.2. About the second distribution system]
Next, a second distribution system in the content distribution system S of the present embodiment will be described with reference to FIGS. 1, 11, and 12.

  As shown in FIG. 1, the second distribution system of the content distribution system S includes a plurality of terminal devices 2a1, 2a2, 2b1 to 2b4, 2c1 to 2c8 with a tree-like hierarchical structure and logically arranged in multiple layers. The content data is streamed from the content distribution device 1 to the terminal device 2 connected upstream of the tree-like hierarchical structure to the terminal device 2 connected downstream by the relay function of each terminal device 2. Configured to be delivered. This tree-like hierarchical structure is configured for each broadcast channel distributed by the content distribution apparatus 1.

  In the second distribution system of the content distribution system S, a plurality of terminal devices 2 are arranged in a multi-layered manner in a tree-like hierarchical structure with the content distribution device 1 as the apex (here, the 0th layer for convenience) for each broadcast channel. It is managed by the connection management device 3 so as to be logically connected. In the present embodiment, a tree-like hierarchical structure is described. However, the present invention is not limited to this, and a plurality of terminal devices 2 may be logically connected in multiple layers in a chain-like hierarchical structure. The terminal devices 2a1 and 2a2 may be referred to as a terminal device 2a for convenience, the terminal devices 2b1 to 2b4 may be referred to as a terminal device 2b for convenience, and the terminal devices 2c1 to 2c8 may be referred to as a terminal device 2c for convenience.

  Here, the operation of distributing content data in the second distribution system will be briefly described with reference to FIG. FIG. 11 is an explanatory diagram of the distribution operation of the second distribution system in the content distribution system S.

  As shown in FIG. 11, content data that is stream-distributed by the content distribution device 1 in the second distribution system is input to the content distribution device 1 by the content input device 4. That is, the content data is transmitted from the content input device 4 to the content distribution device 1, received by the content distribution device 1, and held in a hard disk device 203 (see FIG. 13) described later.

  When the terminal device 2 that does not participate in the second distribution system in the content distribution system S, in other words, the terminal device 2 that does not constitute any tree-like hierarchical structure of the broadcast channel, when participating in the second distribution system, first, Then, an application for participating in the second distribution system is started, a storage area for the second distribution system is secured in a later-described main storage device 205 (see FIG. 13) included in the own device 2, and then the connection management device A connection destination introduction request is transmitted to 3.

  Note that the storage area for the second distribution system secured here functions as a ring buffer 220 or the like described later.

  As shown in FIG. 11, when the connection management device 3 receives a connection destination introduction request from a terminal device 2 that does not participate in the second distribution system in the content distribution system S, the connection management device 3 has a tree-like hierarchical structure of the second distribution system. Based on the status or the like, a connection destination candidate (content distribution apparatus 1 or terminal apparatus 2) to be connected as an upstream apparatus for receiving streaming distribution of the terminal apparatus 2 is selected. Then, the connection management device 3 notifies the terminal device 2 of the location information (such as the IP address and port number of the connection destination candidate) and the communication protocol of the connection destination candidate thus selected. The connection destination introduction request is transmitted from the connection management device 3 when switching to another channel or when the connection with the terminal device 2 connected upstream in the tree-like hierarchical structure is disconnected.

  In the content distribution system S, when the communication protocol and the port number are already fixed, the port number and the communication protocol to the terminal device 2 need not be notified. Here, MMS (Microsoft Media Server) protocol, RTSP (Real Time Streaming Protocol), etc. are used as communication protocols. As the format of the content data, ASF (Advanced Streaming Format), WMA (Windows (registered trademark) Media Audio), WMV (Windows (registered trademark) Media Video), or the like is used.

  When the terminal device 2 receives the location information of the connection destination candidate from the connection management device 3, the terminal device 2 requests the connection destination candidate to participate in (connect to) the second distribution system with the location information as the destination, and thereby the terminal device 2 is incorporated into a tree-like hierarchical structure in the second distribution system of the content distribution system S. That is, the terminal device 2 can receive the content data distributed from the content distribution device 1.

  In the second distribution system in the content distribution system S, the terminal device 2 participates in each channel one after another in this way, so that a plurality of terminal devices 2 have a tree-like hierarchical structure and logically function in multiple layers with the content distribution device 1 as a vertex. Connected. Then, the content data distributed from the content distribution device 1 is sequentially relayed to the downstream terminal devices 2 in the tree-like hierarchical structure by the relay function of each terminal device 2 and streamed to the plurality of terminal devices 2.

  That is, as shown in FIG. 11, when content data is transmitted from the content distribution device 1 to the terminal devices 2a1, 2a2 (first-layer terminal devices) and the terminal devices 2a1, 2a2 receive the content data, the downstream terminal device The received content data is relayed sequentially to 2b1 to 2b4 (second layer terminal devices). When receiving the content data, the terminal devices 2b1 to 2b4 relay the received content data sequentially to the downstream terminal devices 2c1 to 2c8 (third layer terminal devices). In FIG. 11, only a hierarchical structure of one broadcast channel among a plurality of broadcast channels is shown for easy understanding.

  The terminal device 2 includes the location information of the terminal device 2 or the content distribution device 1 upstream of the position of the embedded tree-like hierarchical structure and the terminal device 2 downstream of the position of the hierarchical structure of the embedded tree place. The location information is stored in a hard disk device 203 to be described later, and content data is relayed based on the location information stored in this way. Further, the content data to be distributed is divided into a plurality of packets and sequentially distributed, and the data thus divided and distributed is called a content packet.

  In this way, the content data distributed to the terminal device 2 is distributed to the terminal device 2 constituting the tree-like hierarchical structure for each broadcast channel. The distributed content data includes reproduction time information in addition to content data such as music and movies. Then, the plurality of terminal devices 2 that have received the content data perform the reproduction of the sequentially transmitted content data based on the reproduction time information.

  Here, the ring buffer 220 in the terminal device 2 will be described. FIG. 12 is a diagram conceptually illustrating a configuration in which content data is received using the ring buffer 220 in the terminal device 2 and is played back or relayed to the downstream terminal device 2.

  When the terminal device 2 participates in the second distribution system, the streaming device sequentially receives the content packets streamed from the upstream device of the tree-like hierarchical structure in the participating broadcast channel. The contained content data is temporarily stored in the ring buffer 220. The content data temporarily stored in the ring buffer 220 is taken out of the ring buffer 220 and played by the player as the playback means of the terminal device 2 at the playback time.

  Here, as shown in FIG. 12, new content data is sequentially stored in the ring buffer 220 in the clockwise direction, and the oldest content data is rewritten to new content data. That is, if the point written to the ring buffer 220 by the streaming receiver is A, the point A moves clockwise.

  Note that the ring buffer 220 in FIG. 12 is conceptually shown, and is not actually ring-shaped, but the control unit of the terminal device 2 stores the oldest content accumulated in a predetermined address area in the storage area. This is realized by sequentially rewriting data with new content data.

  In addition, the playback time information is stored in the content data as described above, and the player has content data having playback time information that matches the current time among the content data stored in the ring buffer 220 (here, FIG. 12). The content data of the middle B point) is taken out from the ring buffer 220 and sequentially reproduced.

  With such a ring buffer 220, content data before the playback time is accumulated, and content packet loss that occurs intermittently depending on the state of the network 6 by the playback time is dealt with. In other words, the content distribution apparatus 1 distributes content data while ensuring a margin sufficient to perform packet loss compensation processing. Note that the packet loss compensation process is a process in which if a packet from the host device does not arrive after waiting for a certain period of time, a packet retransmission request is sent to the host device and the packet is transmitted again from the host device. In the loss compensation process, a series of processes must be performed as described above, and it takes a certain amount of time. Therefore, it is necessary to secure a margin as described above.

  Here, when two other terminal devices 2 are connected downstream of the tree-like hierarchical structure, two streaming transmitters are provided in the terminal device 2 as shown in FIG. The streaming transmitter stores the content data stored in the ring buffer 220 in a data area of the content packet for each predetermined amount, generates a content packet, and transmits this content to the other terminal devices 2 connected downstream. Send packets sequentially.

  In the terminal device 2 of the present embodiment, the content data included in the content packet transmitted from the upstream device in the tree shape is extracted and stored in the ring buffer 220. However, the content packet is stored in the ring buffer 220 as it is. You may make it do. In any case, the streaming transmitter transmits the content packet obtained by replacing the transmission destination and transmission source information of the content packet received by the streaming receiver to the downstream terminal apparatus 2 in the tree-like hierarchical structure. The streaming receiver corresponds to a streaming receiving means described later, the player corresponds to a streaming reproducing means described later, and the streaming transmitter corresponds to a streaming relay means described later.

  In this way, when the terminal device 2 participates in the second distribution system, it secures the ring buffer 220 for temporarily storing the content data, thereby compensating for the packet loss while prebuffering the content packet, The influence of packet loss that occurs on the route of the network 6 is avoided.

  As described above, in the second distribution system of the content distribution system S, the content data transmitted from the content distribution device 1 is stream-distributed to the plurality of terminal devices 2, and the content is reproduced at the same time on the plurality of terminal devices 2. be able to. That is, the content distribution system S realizes streaming distribution in a broadcast format to a plurality of terminal devices 2 using P2P.

[3. Description of the configuration of the terminal device 2]
Next, the configuration and the like of the terminal device 2 according to the present embodiment will be specifically described with reference to FIGS.

  FIG. 13 is a block diagram showing a configuration of the terminal device 2, and FIG. 14 is an explanatory diagram showing the first distribution system storage unit 205b for the first distribution system in the main storage device 205 of the terminal device. FIG. 15 is an explanatory diagram showing a storage area reserved for the first distribution system and a storage area reserved for the second distribution system by the information management means.

  The terminal device 2 of the present embodiment can apply a general personal computer or a dedicated terminal, and can participate in the second distribution system while participating in the first distribution system. Specifically, it is configured as shown in FIG.

  That is, as shown in FIG. 13, the terminal device 2 participates in a CPU (Central Processing Unit) 202, a rewritable main storage device 205 that stores (stores) various programs, and the first distribution system. A hard disk device 203 that stores various data such as an application for participating in the second distribution system, a content distribution device 1, a connection management device 3, a content input device 4, and a contact via the network 6 A network interface 204 for performing wired communication between the first introduction device 5 and another terminal device 2 and an input unit such as a keyboard 207 and a mouse 208 capable of inputting predetermined information by a user operation are controlled. Image from peripheral device control chip 206 and CPU 202 The video chip 209 that receives the data and writes it in an internal video memory (not shown) and displays the data written in the video memory on a built-in display 210 to be described later, and a display corresponding to the signal transmitted from the video chip 209 A built-in display 210, a sound source chip 211 having a sound source such as an FM sound source (Frequency Modulation) or Wave Table sound source, and a built-in speaker 212 that converts an audio signal output from the sound source chip 211 into a sound wave. These various components are connected to each other via a system bus 201.

  In the present embodiment, the CPU 202 and the main storage device 205 constitute a control unit 230. The network interface 204 is connected to the network 6 via the router 10b. This router 10b corresponds to the router 10 shown in FIG.

  Further, with the keyboard 207 and the mouse 208 as described above, operations such as purchase of content in the content distribution system S are possible.

(About the main storage device 205)
The main storage device 205 also includes an OS (operating system) program 217 for providing basic functions of the terminal device 2 as a computer, a screen control program 218 for controlling the built-in display 210, a first distribution system, A program storage unit 205a is provided that stores a decoder program 219 and the like for decoding and reproducing the content data received by the second distribution system.

  In addition, the main storage device 205 is a storage area reserved for the first distribution system when it participates in the first distribution system (hereinafter referred to as “first distribution system storage area 250”). For the first distribution system that functions and functions as a storage area reserved for the second distribution system (hereinafter referred to as “second distribution system storage area 251”) when participating in the second distribution system. Also, a second distribution system storage unit 205b is provided.

  When the control unit 230 starts an application for participating in the first distribution system, the first distribution system and second distribution system storage unit 205b functions as the first distribution system storage area 250, and Store information.

  That is, as shown in FIG. 14A, the first distribution system storage area 250 includes a routing table RT used in DHT routing, an IP address of the content holding terminal device, a content ID held by the content holding terminal device, and the like. An index table 222 in which content holding terminal information (hereinafter also referred to as “index cache information”) is described; catalog information 224 that is content data list information in which titles, authors, genres, and the like of currently downloadable content are described; Various information for receiving content data by the first distribution system such as various message information 225 and content purchase program 221 used at the time of DHT routing is stored.

  On the other hand, when the control unit 230 participates in the first distribution system and executes the application for participating in the second distribution system, the first distribution system and second distribution system storage unit 205b executes the first distribution system storage unit 205b. A part of the distribution system storage area 250 is caused to function as the second distribution system storage area 251 to store the following information.

  That is, the second distribution system storage area 251 receives the content data that is streamed and distributed directly from the content distribution device 1 or to another terminal device 2 to the downstream terminal device 2 in the streaming reception and tree-like hierarchical structure. Stream control program 215 for streaming transmission, location information (IP address and port number) of terminal device 2 (or content distribution device 1) connected to a tree-like hierarchical structure and a tree-like hierarchical structure Streamed content data is received by the second distribution system such as the topology management program 216 for managing the location information of the further downstream terminal device 2 and the ring buffer 220 for temporarily storing the streamed received content data. And streamy It is provided to store the information for graying delivery.

  Here, the OS program 217 is read and executed by the CPU 202, thereby causing the terminal device 2 such as a function related to input / output of the keyboard 207 and the mouse 208 and memory management such as the main storage device 205 and the hard disk device 203. It enables the basic functions of a computer to be executed. Then, with the OS program 217 being executed by the CPU 202, the above-described stream control program 215, topology management program 216, screen control program 218, decoder program 219, content purchase program 221 and the like are read from the main storage device 205. Executed.

  The OS program 217, stream control program 215, topology management program 216, screen control program 218, decoder program 219, content purchase program 221 and the like are downloaded to the main storage device 205 from a server connected to the network 6, for example. Alternatively, it may be recorded on a storage medium such as a CD-ROM and then read into the main storage device 205 via the storage medium.

(About the control unit 230)
The control unit 230 includes the CPU 202 and the main storage device 205 as described above, and the CPU 202 reads out various programs 215 to 219 and 221 stored in the main storage device 205 and various applications stored in the hard disk device 203. To execute overall control of the terminal device 2 and perform storage capacity detection means, information amount acquisition means, participating terminal number detection means, reception speed detection means, information management means, catalog information reception means, identification, which will be described later Information acquisition means, content data storage control means, download processing means, content holding terminal information receiving means, download transmission request means, download data receiving means, message destination determination means, content holding terminal device information selection means, content holding terminal device information reply Means, content identification information Means, content registration message generation means, content registration message transmission means, message transfer means, content reproduction means, connection means, streaming reception means, streaming relay means, streaming reproduction means, display control means, decoding means, etc. ing.

  The CPU 202 activates an application for participating in the first distribution system stored in the hard disk device 203 or an application for participating in the second distribution system, so that the storage capacity detection means, the information amount acquisition means, and the participation As a terminal number detection means, a reception speed detection means, an information management means, and when the CPU 202 executes the content purchase program 221, a catalog information reception means, an identification information acquisition means, a content data storage control means, a download processing means, a content Holding terminal information receiving means, download transmission request means, download data receiving means, message destination determination means, content holding terminal device information selection means, content holding terminal information return means, content identification information calculation means, content registration message As a content reproduction means such as a message generation means, a content registration message transmission means, and a message transfer means, the CPU 202 executes a stream control program 215, and as a streaming reception means, a streaming relay means, etc., and the CPU 202 executes a topology management program 216. As a connection means, as a display control means when the CPU 202 executes the screen control program 218, and as a decoding means and a streaming playback means as the CPU 202 executes the decoder program 219, respectively. It is supposed to function.

(About storage capacity detection means)
The storage capacity detection means detects the capacity of the storage area required by participating in the second distribution system.

  That is, the storage capacity detecting means calculates the storage capacity of the ring buffer 220 necessary for streaming reception of the content data from the information amount (bit rate) of the content data to be received by the second distribution system. At the same time, by calculating the sum of the capacity of the ring buffer 220 and the storage capacity capable of storing the stream control program 215 and the topology management program 216, the storage area required by participating in the second distribution system is calculated. Detect capacity.

  In addition, when calculating the storage capacity required for the ring buffer 220, the storage capacity detection means determines the amount of content data stream-received per unit time by the second distribution system based on the detection result by the reception speed detection means described later. In addition to the calculation, the necessary storage capacity of the ring buffer 220 can be calculated based on the calculation result.

(About information acquisition means)
In the content holding terminal information held by itself, the information amount acquisition means is a content holding terminal held by the terminal device from the terminal device (root terminal device) that manages the content holding terminal information to be deleted. By acquiring the information amount of information, the amount of node information held by the terminal device is acquired.

(About the number of participating terminals detection means)
The participating terminal number detecting means detects the number of terminal devices 2 participating in the first distribution system.

  Here, as a method of detecting the number of terminal devices 2 participating in the first distribution system, the terminal device described in the routing table RT is referred to the routing table RT stored in the terminal device 2 itself. The number of terminal devices 2 participating in the first distribution system is detected from the number of 2 by estimating the number.

  Further, as a method of detecting the number of terminal devices 2 participating in the first distribution system, from the contact introduction device 5 that manages the connection status of all the terminal devices 2 participating in the first distribution system. The number of terminal devices 2 currently participating in the first distribution system can be acquired.

(Reception speed detection means)
When the terminal device 2 participates in the second distribution system, the reception speed detection means is used by the device from the terminal device 2 (or the content distribution device 1) that is connected upstream of the tree-like hierarchical structure. The communication speed (bit rate) between the device and the terminal device 2 is indirectly determined from the type of the communication line (optical line, ADSL line, normal telephone line, etc.). To detect.

  Here, the reception speed detection means detects the communication speed according to the type of the communication line, but the present invention is not limited to this. For example, the upstream terminal apparatus 2 connected to the tree-like hierarchical structure (or Before the content data is transmitted from the content distribution device 1), the data of a predetermined file size is transmitted as the data for speed test, and communication is performed from the time required until the reception of the data is completed. You may comprise so that a speed may be detected.

(About information management means)
When the terminal device 2 participates in the first distribution system, the information management means secures the first distribution system storage area 250 in the first distribution system / second distribution system storage unit 205b of the main storage device 205. When the terminal device 2 participates in the first distribution system and participates in the second distribution system, a part of the first distribution system storage area 250 is used as the second distribution system storage area 251. It is to function.

  That is, when the terminal device 2 is turned on, the information management unit first stores the first distribution system storage area 250 in the first distribution system / second distribution system storage unit 205b in the main storage device 205. Secure.

  At this time, as shown in FIG. 15 (a), the information management means secures a storage area necessary for downloading the content data by the first distribution system as the first distribution system storage area 250. In the first distribution system storage area 250, a content purchase program 221, a routing table RT, an index table 222, catalog information 224, various message information 225 and the like necessary for downloading content data by the first distribution system (see FIG. 14 (a)) is stored.

  Various types of information stored in the first distribution system storage area 250 are information stored in the hard disk device 203 before the terminal device 2 is turned off last time. However, the routing table RT, the index table 222, and the catalog information are once read from the hard disk device 203 and stored in the first distribution system storage area 250, and then it is determined whether these pieces of information are the latest. If it is determined that the information is not the latest, the information is updated as needed.

  In this way, the information management means secures the first distribution system storage area 250 in the first distribution system and second distribution system storage unit 205b and prepares for the download of content data by the first distribution system.

  Thereafter, when the user operates the keyboard 207 or the mouse 208 in order to participate in the second distribution system in a state where the terminal device 2 is participating in the first distribution system, the information management unit performs the storage capacity detection unit described above. In accordance with the detection result, a part of the information stored in the first distribution system storage area 250 is deleted as shown in FIG.

  That is, the information management unit determines whether or not a part of the first distribution system storage area 250 is to function as the second distribution system storage area 251 according to the detection result of the storage capacity detection unit.

  At this time, the information management means calculates the storage capacity of the ring buffer 220, the stream control program 215, and the topology management program 216, which are calculated by the storage capacity detection means and are necessary for streaming reception of content data by the second distribution system. The total storage capacity that can be stored is compared with the storage capacity of the free area in the first distribution system / second distribution system storage unit 205b, and the storage capacity of the free area is calculated by the storage capacity detection means. When it is determined that the storage area is larger, a part of the information stored in the first distribution system storage area 250 is deleted.

  On the other hand, if the information management unit determines that the storage capacity of the free area of the first distribution system / second distribution system storage unit 205b is larger than the storage capacity detected by the storage capacity detection unit The free area is caused to function as the second distribution system storage area 251.

  As a result, the information management means can be used for the first distribution system when there is enough free space in the first distribution system and second distribution system storage unit 205b to sufficiently secure the second distribution system storage area 251. Since it is not necessary to perform a process for causing the storage area 250 to function as a storage area for the second distribution system, the processing load on the information management unit can be reduced accordingly.

  In addition, when deleting a part of the information stored in the first distribution system storage area 250, the information management means first storage system storage area according to the information amount acquired by the information amount acquisition means. It is determined whether or not to delete the content holding terminal information constituting the index table 222 in 250.

  That is, the information management unit acquires the information amount of the content holding terminal information to be deleted held by the root terminal device from the root terminal device that manages the content holding terminal information to be deleted by the information amount acquiring unit. If the acquired amount of information exceeds a predetermined threshold, the content holding terminal information to be deleted is deleted from the index table 222 in the first distribution system storage area 250.

  Since the content holding terminal information to be deleted at this time is information that can be acquired from another terminal device 2 if it is necessary again even if it is deleted, the content data is received by the first distribution system. Will not be disturbed.

  In addition, when the information management unit manages a plurality of types of content holding terminal information to be deleted, the information amount acquisition unit determines the information amount of the content holding terminal information related to a plurality of types of content data from a plurality of root terminal devices And the content holding terminal information with the larger information amount among the acquired plural types of information amounts is deleted in order.

  Therefore, even if the deleted content holding terminal information is needed again, there are many root terminal devices on the network 6 that hold the content information. Can be easily obtained from the root terminal device.

  On the other hand, the information management unit deletes information other than the content holding terminal information stored in the first distribution system storage area 250 when the information amount acquired by the information amount acquisition unit does not exceed a predetermined threshold. To do.

  As described above, when information other than the content holding terminal information stored in the first distribution system storage area 250 is deleted, the information management means stores the catalog information or the routing table from the first distribution system storage area 250. A part of node information constituting the RT is deleted.

  Further, the information management means functions as the second distribution system storage area 251 among the storage areas reserved as the first distribution system storage area 250 according to the reception speed acquired by the reception speed detection means. Expand or shrink the area.

  That is, when the reception speed acquired by the reception speed detection means is relatively low, the amount of content data stored in the ring buffer 220 per unit time is relatively small, so the storage area that functions as the ring buffer 220 is reduced. Even in this case, the content data stream-received by the second distribution system can be reliably stored in the ring buffer 220.

  Therefore, the information management means, when the reception speed acquired by the reception speed detection means is relatively low, out of the storage areas secured as the first distribution system storage area 250, the second distribution system storage area 251. As a result, the amount of information to be deleted from the first distribution system storage area 250 is reduced.

  On the other hand, when the reception speed acquired by the reception speed detection means is relatively high, the amount of content data accumulated in the ring buffer 220 per unit time is relatively large, so the storage area that functions as the ring buffer 220 is expanded. Otherwise, the content data stream-received by the second distribution system cannot be reliably stored.

  Therefore, the information management means, when the reception speed acquired by the reception speed detection means is relatively high, out of the storage areas secured as the first distribution system storage area 250, the second distribution system storage area 251. As a result, the amount of information to be deleted from the first distribution system storage area 250 is increased.

  As described above, when the amount of information to be deleted from the first distribution system storage area 250 increases, the information management unit stores the index table 222 among the information stored in the first distribution system storage area 250. Either the content holding terminal information or the catalog information that is configured is deleted.

  Further, when the information management means determines that the storage area necessary for the ring buffer 220 cannot be sufficiently secured even if either the content holding terminal information or the catalog information is deleted, the information holding terminal information and Both the catalog information and the catalog information are deleted from the first distribution system storage area 250.

  If the information management unit determines that the storage area necessary for the ring buffer 220 cannot be secured even if both the content holding terminal information and the catalog information are deleted, the information management unit configures the routing table RT. Delete part of the node information.

  At this time, the information management means does not delete information essential for performing DHT routing, such as the terminal ID of the other terminal device 2 and the IP address of the terminal device 2, and does not delete it from the own terminal device 2 to the root terminal device. Information that does not cause any trouble when performing DHT routing, such as information indicating the number of terminal devices (pops) existing on the transfer path when transferring information to, is deleted.

  In the information stored in the first distribution system, the priority of deletion by the information management means is the order of the content holding terminal information, catalog information, and part of the node information described in the routing table RT.

  That is, when deleting information from the first distribution system storage area 250, the information management means first deletes the content holding terminal information, and if it still cannot secure a sufficient storage area as the ring buffer 220, catalog information is stored. Even if a sufficient storage area cannot be secured as the ring buffer 220, a part of the node information is deleted.

  By providing the deletion priority in this way, the information management means, when deleting information from the first distribution system storage area 250, information that is unlikely to hinder DHT routing even if the information is deleted, in other words, In this case, it is possible to delete information in order from the information that is less likely to cause trouble when the content data is downloaded by the first distribution system.

  Further, the information management means deletes a part of the first distribution system storage area 250 when the number of terminal devices 2 detected by the participating terminal number detection means exceeds a predetermined threshold.

  In other words, if more than a predetermined number of terminal devices 2 participate in the first distribution system, the information management means can delete the information stored in the first distribution system storage area 250 even if the information is deleted. When it becomes necessary, the information can be acquired from the other terminal devices 2 participating in the first distribution system.

  In addition, when the terminal device 2 is a root terminal device of predetermined content data, the information held by itself is required even if the information stored in the first distribution system storage area 250 is deleted. The terminal device 2 that can obtain the information from the other terminal devices 2 participating in the first distribution system may interfere with the other terminal devices 2 participating in the first distribution system. Absent.

  In addition, when the information management means has a large amount of information to be deleted in the first distribution system storage area 250 and the information is needed later, it is difficult to obtain the information from another terminal device 2 or the like. 15B, before deleting information from the first distribution system storage area 250, the information to be deleted is temporarily stored in the hard disk device 203, as shown in FIG.

  In this case, the hard disk device 203 functions as another storage unit for storing information to be deleted from the first distribution system storage area 250.

  In this way, the information management unit deletes the information from the first distribution system storage area 250 and then deletes the deleted information or the hard disk in the first distribution system storage area 250 as shown in FIG. In order to cause the area storing the information stored in the device 203 to function as the second distribution system storage area 251, and to download the content data in the second distribution system storage area 251 by the second distribution system Necessary stream control program 215, topology management program 216, ring buffer 220, etc. (see FIG. 14B) are stored.

  In this way, the information management means secures the second distribution system storage area 251 in the first distribution system / second distribution system storage unit 205b to prepare for streaming reception of content data by the second distribution system.

  Then, after the terminal device 2 leaves the second distribution system, the information management unit deletes the information stored in the second distribution system storage area 251 as shown in FIG.

  Thereafter, when the information deleted from the first distribution system storage area 250 is stored in the hard disk device 203, the information management means reads the information from the hard disk device 203 as shown in FIG. Again, the first distribution system storage unit 205b is stored in the first distribution system storage area 250 secured in the first distribution system storage unit 205b and the second distribution system storage unit 205b is configured as shown in FIG. Return to the state shown in a).

  In addition, when the information deleted from the first distribution system storage area 250 is not stored in the hard disk device 203, the information management means stores the information deleted from the first distribution system storage area 250 in the other terminal device 2. Is stored in the first distribution system storage area 250 secured in the first distribution system / second distribution system storage unit 205b again, and is stored in the first distribution system / second distribution system storage unit. 205b is returned to the state shown in FIG.

  In this way, when the information management means participates in the second distribution system in a state of participating in the first distribution system, a part of the first distribution system storage area 250 functions as the second distribution system storage area 251. By doing so, it is possible to secure a storage area having a sufficient capacity as the ring buffer 220 used in the second distribution system, so that the second distribution system does not hinder the streaming reception of the content data, and the second distribution When not participating in the system, it is not necessary to secure the second distribution system storage area 251, so that the main storage device 205 of the terminal device 2 can be used effectively.

(About catalog information receiving means)
The catalog information receiving unit has a function of receiving catalog information transmitted from the content input device 4. The catalog information transmitted from the content input device 4 is information in which the title of content data currently downloadable in the first distribution system and the content ID are associated, and when the terminal device 2 participates in the first distribution system. The content input device 4 transmits the catalog information to the content input device 4 in response to the request. Further, when a predetermined number of content data is newly input to the content distribution device 1 or the terminal device 2, the content input device 4 transmits the updated catalog information to each terminal device 2.

(About identification information acquisition means)
The identification information acquisition unit is content that is identification information of content data requested to be downloaded in order to acquire the content data requested to be downloaded by the first distribution system when the user performs a download request operation regarding desired content data. Get an ID. That is, the identification information acquisition unit acquires the content ID that is the identification information of the content data requested for download from the catalog information received by the catalog information reception unit.

  Note that the identification information acquisition unit may acquire only the content ID of the content data requested to be downloaded from the content input device 4. In this case, the identification information acquisition means transmits the title of the content data requested for download to the content input device 4 and acquires the content ID of the content data requested for download.

  Further, the identification information acquisition means may obtain the content ID of the content data requested to be downloaded by the content identification information calculation means described later. That is, the content ID is obtained by hashing with the hash function using the title of the content data requested to be downloaded as a keyword. Thus, by obtaining the content ID using the title of the content data requested for download as a keyword, the download processing in the first distribution system in the terminal device 2 is facilitated. The titles of content that can be downloaded by the first distribution system are acquired from the content input device 4 in the form of a list or the like, and the content identification information calculation means acquires the title of the content from the catalog information or the like that is the list. By doing so, the content ID can be calculated.

(About content data storage control means)
The content data storage control unit stores the content data downloaded by the first distribution system in the content data storage area of the hard disk device 203.

(About download processing means)
The download processing unit has a function of downloading the content data requested to be downloaded from the content holding terminal devices participating in the first distribution system based on the content ID of the content data acquired by the identification information acquiring unit. And content holding terminal information receiving means, download transmission requesting means, download data receiving means, and the like.

(About content holding terminal information receiving means)
The content holding terminal information receiving unit first searches for a content holding terminal device that holds the content data requested to be downloaded based on the content ID of the content data acquired by the identification information acquiring unit.

  The search for the content holding terminal device generates a content search message using the content ID acquired by the identification information acquisition means as the destination identification information, and routes the IP address of the terminal device 2 having the terminal ID in the same area as the content ID. This is done by taking out from the table RT and transmitting a content search message to the terminal device 2.

  The content holding terminal information receiving unit receives the IP address of the content holding terminal device that holds the content data of the content ID acquired by the identification information acquiring unit from the root terminal device in response to the content search message.

  In this way, the content holding terminal information receiving means receives the content holding terminal information related to the content holding terminal device that holds the content data requested to be downloaded.

(Download transmission request means)
The download transmission request means requests the content holding terminal apparatus corresponding to the content holding terminal information received by the content holding terminal information receiving means to transmit the content data requested for download via the network 6 (hereinafter referred to as “download transmission request”). "). This download transmission request sets the content ID of the content data corresponding to the download request with the IP address of the content holding terminal device as the destination. When there are a plurality of content holding terminal devices searched by the content holding terminal information receiving means, a download transmission request is made to one of the neighboring content holding terminal devices.

  Here, the “neighboring content holding terminal device” refers to a terminal device 2 that makes a download transmission request, a terminal device having a terminal ID close to the content holding terminal device in DHT routing, or a content holding terminal device close to the physical network. means. In particular, when the content holding terminal device that makes a download transmission request is a content holding terminal device that is close to the physical network, the content data can be downloaded from the content holding terminal device in a short time. Note that “close to the physical network” means that the message arrival time from the terminal device that issues the download transmission request is short, or that the number of pops (number via the router) from the terminal device that issues the download transmission request is small. To do.

(About download data receiving means)
The download data receiving unit receives the content data requested to be downloaded from the content holding terminal device that holds the content data requested to be downloaded via the network 6. The content data transmitted from the content holding terminal device is not a streaming format as in the second distribution system, but is a download format data.

  The content data received by the download receiving means is stored in the content data storage area (corresponding to the content data storage means) of the hard disk device 203 by the control unit 230.

(About message destination determination means)
The message destination determination unit determines whether the received message is addressed to the terminal device 2 based on the destination identification information of the message received via the network 6 and the routing table RT. The message determined by the message destination determination means is the above-described content search message, content registration message, or the like.

  Whether or not the received message is addressed to the own terminal device 2 is determined based on the routing table RT extracted from the destination terminal ID (destination identification information) included in the message. That is, when various messages are received via the network interface 204, the message destination determination unit compares the destination identification information included in the received message with the terminal ID stored in the routing table RT, and determines the destination included in the message. If it is determined that the terminal ID on the routing table RT closest to the identification information is the terminal ID of the own terminal apparatus 2, it is determined that the message is addressed to the own terminal apparatus 2.

(About content holding terminal information selection means)
When the content holding terminal information selection unit determines that the message received via the network 6 by the message destination determination unit is addressed to the own terminal device 2 and is a content search message, the content search message is targeted from the index table 222. The IP address of the content holding terminal device that holds the content data of the content ID to be selected is selected. If there are a plurality of content holding terminal device IP addresses in the index table 222, all or some of them are selected.

(About content holding terminal information return means)
The content holding terminal information return means returns the IP address of the content holding terminal apparatus selected by the content holding terminal information selection means to the request terminal apparatus via the network 6.

(About content identification information calculation means)
The content identification information calculation means calculates the content ID that is the identification information of the content data by calculating the specific information of the content data by a predetermined hash function as described above.

(About content registration message generation means)
When the content registration message generating means receives the content data from the content input device 4, the content registration message generating means stores the received content data in the hard disk device 203 as the content data storage means. Further, a content registration message including the terminal ID and IP address of the terminal device is generated using the content ID obtained by calculating the content title of the content data by the content identification information calculation means as the destination identification information.

(About content registration message transmission means)
The content registration message transmission unit transmits the content registration message generated by the content registration message generation unit from the terminal ID of the terminal device 2 stored in the routing table RT based on the content ID of the content data stored in the hard disk device 203. Select the destination terminal device and transmit. For example, when the routing table RT as shown in FIG. 4 and FIG. 5 is provided and the content ID of the content data stored in the hard disk device 203 is “1221”, the content registration message transmitting means transmits the routing table RT. Terminal ID “1221” is selected as the destination terminal device, and the IP address “21.13.21.13” of the terminal device with the terminal ID “1221” is extracted. Then, the content registration message is transmitted using the IP address “21.13.21.13” as the transmission destination terminal device. The destination identification information of this content registration message is “1221”.

(About message transfer means)
When the message transfer means determines that the message received via the network 6 is not addressed to its own terminal device, the message transfer means determines the IP address of the transfer destination terminal device based on the destination identification information of the received message. Is transferred from the routing table RT, and the received message is transferred to the terminal device 2 as the transfer destination.

(About content playback means)
The content reproduction means retrieves and reproduces the content data stored in the hard disk device 203, and the content data is reproduced by operating the video chip 209 and the sound source chip 211.

(About connection means)
The connection means transmits a connection destination introduction request to the connection management device 3 via the network 6 in order to cause the terminal device 2 to participate in the second distribution system of the content distribution system S, and then from the connection management device 3 to the network 6. To connect to the notified connection destination candidate.

  More specifically, the connection means transmits a registration request to the connection management device 3 via the network 6 to cause the terminal device 2 to participate in the second distribution system of the content distribution system S and to the connection management device 3. It has a function of registering and requesting a connection destination candidate from the connection management device 3 by transmitting a connection destination introduction request via the network 6. The registration request and the connection destination introduction request include the IP address of the terminal device 2 itself.

  Further, the connection means responds to the connection destination introduction request transmitted to the connection management device 3, and information on connection destination candidates notified from the connection management device 3 via the network 6, that is, the location of the terminal device 2 of the connection destination candidate It has a function of receiving information such as IP address and port number (hereinafter, abbreviated as “connection destination candidates” including information on connection destination candidates).

  Further, the connection unit has a function of performing logical connection to the connection destination candidate based on the received information about the connection destination candidate. In other words, the connection means makes a connection request with the destination IP address and port number as the destination based on the information about the destination candidate, and makes a logical connection with the destination candidate. By connecting to the connection destination candidates in this way, it is possible to participate in the second distribution system, that is, to incorporate the own terminal device 2 into a part of the tree-like hierarchical structure.

(About streaming receiving means)
The streaming receiving means is transmitted as a content packet from the upstream device, that is, the content distribution device 1 logically connected upstream in the tree-like hierarchical structure or the terminal device 2 connected upstream by the second distribution system via the network interface 204. The content data to be streamed is received, and the content data thus streamed is stored in the ring buffer 220 sequentially. It should be noted that the content data receiving means and the content data relay means described later can use a known streaming distribution protocol, or can use a unique dedicated protocol.

(About streaming relay means)
The streaming relay means connects downstream the content data streamed via the network 6 from the upstream device in the second distribution system, that is, the content distribution device 1 or the terminal device 2 connected upstream in the tree-like hierarchical structure. Then, the data is transferred to the other terminal device 2 via the network 6.

(About streaming playback means)
The streaming reproduction means has a function of sequentially reproducing the content data sequentially received from the upstream apparatus by the second distribution system via the network interface 204 and sequentially stored in the ring buffer 220.

  This streaming reproduction means realizes this function by operating the sound source chip 211 and the video chip 209, and sequentially retrieves the content data stored in the ring buffer 220 to obtain a predetermined content data format (for example, Wave format). Is input to the sound source chip 211 and the video chip 209, and the content is reproduced.

  The content data converted into a predetermined content data format by the streaming reproduction means is output from the built-in speaker 212 after the audio information is converted into an audio signal by the sound source chip 211 when the content data includes audio information. Is done.

  In addition, when the content data converted into a predetermined content data format by the streaming playback means includes video information, the video information is displayed on the built-in display 210 under the control of the display control means described later.

  Also, the streaming playback means determines the timing for playing back the content data based on the playback start time information included in the content data stored in the ring buffer 220. That is, the playback means is configured to output the content data stored in the ring buffer 220 to the built-in speaker 212 and the built-in display 210 at the playback start time.

(Display control means)
The display control means has a function of controlling the video chip 209 and the built-in display 210 to display content data and various types of information. That is, the display control means can control how the content video and various types of information are displayed on the built-in display 210.

(Decoding means)
The decoding means displays the content data transmitted from the other terminal device 2 on the display 210 and decodes it for output from the speaker 212. That is, the content data transmitted from the other terminal device 2 is encoded in a data format for streaming delivery, for example, a data format such as ASF, WMA, WMV, and the encoded content data is displayed on the display 210. And decoding so that it can be output from the speaker 212.

[2. Operation of connection management device]
Next, the operation of the connection management device 3 in this embodiment will be described with reference to the flowchart shown in FIG. Here, the connection management device 3 is composed of a general-purpose personal computer, and the flowchart shown in FIG. 16 shows processing performed by the control unit of the connection management device 3.

  When the power is turned on, the control unit of the connection management device 3 first determines whether or not the power is off as shown in FIG. Here, when the control unit of the connection management device 3 determines that an operation to turn off the power of the connection management device 3 has been performed (step S1: Yes), the process ends, and an operation to turn off the power is not performed. Is determined (step S1: No), the process proceeds to step S2.

  In step S2, the control unit of the connection management device 3 determines whether or not a connection destination introduction request has been received from the terminal device 2 that intends to participate in the first distribution system, and determines that the connection destination introduction request has been received. In the case (step S2: Yes), the process moves to step S3. When it is determined that the connection destination introduction request has not been received (step S2: No), other processes are performed (step S4), and the subsequent processes are performed. Move to step S1.

  In step S3, the control unit of the connection management device 3 transmits the IP address of the currently connectable terminal device 2 participating in the first distribution system to the terminal device 2 that has transmitted the connection destination introduction request. An introduction process is performed, and then the process proceeds to step S1.

  In this way, the control unit of the connection management device 3 repeats the processing of steps S1 to S4 while the power is turned on, and introduces terminal devices that are connection destination candidates to the terminal device 2 that intends to participate in the first distribution system. .

[3. Operation of terminal device]
Next, the operation of the terminal device according to the present embodiment will be specifically described with reference to the flowcharts shown in FIGS. The following processes are executed by the control unit 230 of the terminal device 2 functioning as each unit described above. In the following description, the control unit 230 of the terminal device 2 is simply referred to as the control unit 230.

(Main process)
When power is turned on, the CPU 202 constituting the control unit 230 first performs an initial setting operation, and then starts an application for participating in the first distribution system stored in the hard disk device 203, The function as 230 is operated, and the first distribution system storage area 250 is secured in the first distribution system storage / second distribution system storage unit 205 b in the main storage device 205.

  Then, the control unit 230 stores the content purchase program and various message information read from the hard disk device 203 in the first distribution system storage area 250, and then executes the main processing shown in FIG. Note that the routing table RT, the index table 222, and the catalog information 224 are sequentially stored in the first distribution system storage area 250 by the control unit 230 executing main processing.

  In this main process, the control unit 230 performs a participation message transmission process as shown in FIG. 17 (step S11).

  Here, the control unit 230 participates in the first distribution system of the content distribution system S to the contact introduction device 5 that manages the connection state of all the terminal devices 2 participating in the first distribution system. , Requesting location information of the contact terminal device to which the participation message should be transmitted.

  And the control part 230 will transmit a participation message with respect to a contact destination terminal device, if the location information of the contact destination terminal device which should transmit a participation message from the contact destination introduction apparatus 5 is sent. Note that the destination identification information of the participation message transmitted at this time is its own terminal ID. The control unit transmits a participation message using the hash value of the IP address of the own device 2 as destination identification information.

  Next, the control unit 230 performs a routing table creation process (step S12). Here, the control unit 230 creates the routing table RT as follows.

  That is, the contact terminal device that has received the participation message transfers the participation message to another terminal device based on the routing table RT held by itself, and at the level of the routing table RT held by itself. The information of the table of 1 is transmitted to the terminal device which is the newly participating terminal device 2M.

  Similarly, other terminal devices to which the participation message is transferred transfer the participation message based on the routing table RT held by the terminal device, and the level 2 table of the routing table RT held by the terminal device itself. Information is transmitted to the terminal device which is the newly participating terminal device 2M.

  In this way, the participation message is sequentially transferred to the other terminal devices 2, and the transfer of the participation message is finished when the terminal device 2 finally arrives closest to the destination identification information.

  And the control part 230 receives sequentially the information of the routing table which the terminal device 2 hold | maintained from each terminal device 2 used as the transfer path | route of the participation message, and memorize | stores it in the memory area 250 for 1st delivery systems. Thus, the information of each level of its own routing table RT is registered in order from the higher level, and the routing table RT necessary for participating in the first distribution system is generated.

  Next, the control unit 230 performs catalog information acquisition processing (step S13). At this time, the control unit 230 receives the catalog information 224 from another terminal device participating in the first distribution system such as a contact terminal device and stores the catalog information 224 in the first distribution system storage area 250.

  Next, the control unit 230 determines whether or not an operation for turning off the power is performed by the user (step S14), and when it is determined that an operation for turning off the power is performed (step S14: Yes). When it is determined that the main process is finished and the operation to turn off the power is not performed (step S14: No), the process proceeds to step S15.

  In step S15, the control unit 230 determines whether or not the user is currently participating in the second distribution system. If the control unit 230 determines that the user is currently participating in the second distribution system (step S15: Yes), the process proceeds to step S15. If the process proceeds to S18 and it is determined that the user is not participating in the second distribution system (step S15: No), the process proceeds to step S16.

  In step S18, the control unit 230 performs the second delivery system participation process described later shown in FIG. 31, and then moves the process to step S19.

  Next, in step S16, the control unit 230 determines whether or not to participate in the second distribution system. Here, the control unit 230 determines whether or not to participate in the second distribution system depending on whether or not an operation for participating in the second distribution system is performed by the user.

  And when it judges that control part 230 participates in the 2nd distribution system (Step S16: Yes), it moves processing to Step S17, and when it judges that it does not participate in the 2nd distribution system (Step S16: No), The process moves to step S19.

  In step S17, the control unit 230 performs a participation process in the second delivery system described later shown in FIG. 23, and then moves the process to step S19.

  In step S19, the control unit 230 determines whether or not the message of the second distribution system has been received. If it is determined that the message has been received (step S19: Yes), the process proceeds to step S20. If it is determined (step S19: No), the process proceeds to step S21.

  In step S20, the control unit 230 performs a process corresponding to the message of the second delivery system described later shown in FIG. 33, and then moves the process to step S14.

  In step S21, the control unit 230 determines whether or not the message of the first distribution system has been received. If it is determined that the message has been received (step S21: Yes), the control unit 230 moves the process to step S22 and receives it. If it is determined that there is not (step S21: No), the process proceeds to step S23.

  In step S <b> 22, the control unit 230 performs processing corresponding to a message of the first delivery system described later shown in FIG. 18, and then moves the processing to step 14. In step S23, the control unit 230 performs another process different from the reception of the content data by the first and second distribution systems, and when the process ends, the process proceeds to step S14.

  Then, the control unit 230 repeatedly performs the processes in steps S11 to S23 while the terminal device 2 is powered on.

(Processing corresponding to the message of the first distribution system)
Next, the process corresponding to the message of the first distribution system performed by the control unit 230 of the terminal device 2 in step S22 of the main process shown in FIG. 17 will be described with reference to FIG.

  In the process corresponding to the message of the first distribution system, when receiving the message of the first distribution system, the control unit 230 determines whether the received message is a content registration message, as shown in FIG. When it is determined that the message is a content registration message (step S31) (step S31: Yes), the process proceeds to step S32. When it is determined that the message is not a content registration message (step S31: No), the process proceeds to step S33.

  In step S32, the control unit 230 performs registration processing in an index table described later shown in FIGS. 19 and 20, and then moves the processing to step S36.

  In step S33, the control unit 230 determines whether or not the received message of the first distribution system is a content search message. If the control unit 230 determines that the message is a content search message (step S33: Yes), the process proceeds to step S34. If it is determined that the message is not a content search message (step S33: No), other processing (step S35) is performed, and then the processing proceeds to step S36.

  In step S34, the control unit 230 refers to the index table 222 held by itself, searches the index cache information corresponding to the search target content by the received content search message, and when the index cache information is found. The index cache information is returned to the terminal device 2 that is the transmission source of the content search message, and then the process proceeds to step S36. If the index cache information corresponding to the search target content is not found, the control unit 230 passes through the process of step S34 and moves the process to step S36.

  Next, in step S36, the control unit 230 determines whether it is the content to be registered in the content registration message or the root terminal device of the content to be searched in the content search message. If it is determined that there is a process (step S36: Yes), the process proceeds to step S37. If it is determined that it is not a root terminal apparatus (step S36: No), the process proceeds to step S38.

  In step S37, the control unit 230 transfers the received message of the first distribution system to the next transfer destination based on the routing table RT held by itself, and then moves the process to step S38.

  In step S38, the control unit 230 performs registration processing in a routing table described later shown in FIGS. 21 and 22 to thereby add the node information included in the content registration message and the content search message to the routing table RT held by itself. The process corresponding to the message of the first distribution system is completed after registration.

(Registration process 1 in the index table)
Next, the index table registration process 1 performed by the control unit 230 in step S32 of the process corresponding to the message of the first distribution system shown in FIG. 18 will be described with reference to FIG.

  In the index table registration process 1, as shown in FIG. 19, the control unit 230 determines whether or not it is currently participating in the second distribution system (step S41), and is participating in the second distribution system. If it is determined that there is any (step S41: Yes), the registration process to the index table is terminated, and the process proceeds to step S36 shown in FIG.

  On the other hand, when it is determined that the control unit 230 is not currently participating in the second distribution system (step S41: No), the process proceeds to step S42, and the index cache information included in the content registration message is held by itself. After registering in the table 222, the registration process in the index table is terminated, and the process proceeds to step S36 shown in FIG.

(Registration process to index table 2)
In the registration process 1 to the index table, the control unit 230 registers the index cache information of the content corresponding to all the received content registration messages in the index table 222 unless it is participating in the second distribution system. However, only the index cache information related to some of the plurality of types of content data may be registered in the index table 222 as the index cache information to be registered.

  In this case, for example, the user sets the terminal device 2 in advance so that only the index cache information related to the content data included in the predetermined genre is registered in the index table 222 as the index cache information to be registered.

  Then, when registering only the index cache information to be registered, the control unit 230 performs the registration process 2 in the index table shown in FIG.

  That is, in the index table registration process 2, as shown in FIG. 20, the control unit 230 determines whether or not it is participating in the second distribution system (step S51), and is participating in the second distribution system. If it is determined that it is (step S51: Yes), the process proceeds to step S52, and if it is determined that it is not participating in the second distribution system (step S51: No), the process proceeds to step S53.

  In step S52, the control unit 230 determines whether or not the index cache information included in the received content registration message is index cache information to be registered, and determines that the index cache information is registration target index cache information. The process proceeds to step S53 (step S52: Yes), and when it is determined that the index cache information is not to be registered (step S52: No), the registration process 2 to the index table is ended, and the process is illustrated in FIG. To step S36 shown in FIG.

  In step S53, the control unit 230 registers the index cache information included in the content registration message in the index table 222 held by the control unit 230, ends the registration process 2 in the index table, and performs the process as shown in FIG. To step S36 shown in FIG.

(Routing table registration process 1)
Next, the registration process 1 to the routing table performed by the control unit 230 in step S38 of the process corresponding to the message of the first distribution system shown in FIG. 18 will be described with reference to FIG.

  In the routing table registration process 1, as shown in FIG. 21, the control unit 230 determines whether or not it is participating in the second distribution system (step S61), and is participating in the second distribution system. (Step S61: Yes), the routing table registration process 1 is terminated, and the process proceeds to step S14 of the main process shown in FIG.

  In step S62, the control unit 230 registers the node information included in the content registration message and the content search message in the routing table RT held by the control unit 230, and then ends the registration process 1 in the routing table. To step S14 of the main process shown in FIG.

(Routing table registration process 2)
In the routing table registration process 1, the control unit 230 registers the node information included in all received content registration messages and content search messages in the routing table RT unless participating in the second distribution system. However, only some of the node information of a plurality of types of node information may be registered in the routing table RT as node information to be registered.

  In this case, for example, the user sets the terminal device 2 so that only the nodes in the content registration message and content search message related to the content included in the predetermined genre are registered in the routing table RT as registration target node information. deep.

  Then, when registering only the registration target node information, the control unit 230 performs the registration process 2 in the routing table shown in FIG.

  That is, in the routing table registration process 2, as shown in FIG. 22, the control unit 230 determines whether or not it is participating in the second distribution system (step S71), and is participating in the second distribution system. If it is determined that there is (step S71: Yes), the process proceeds to step S72, and if it is determined that it is not participating in the second distribution system (step S71: No), the process proceeds to step S73.

  In step S72, the control unit 230 determines whether the node information included in the received content registration message or content search message is node information to be registered, and determines that the node information is to be registered. In the case (step S72: Yes), the process proceeds to step S73. When it is determined that the node information is not the registration target node information (step S72: No), the registration process 2 to the routing table is ended, and the process is illustrated in FIG. To step S14 of the main process shown in FIG.

  Also, in step S73, the control unit 230 registers the node information in the routing table RT held by itself, ends the registration process 2 in the routing table, and moves the process to step S14 of the main process shown in FIG. .

(Participation process in the second distribution system)
Next, the participation process to the second distribution system performed by the control unit 230 in step S17 of the main process shown in FIG. 17 will be described with reference to FIG.

  In the process of participating in the second distribution system, as shown in FIG. 23, the control unit 230 detects the storage capacity necessary for the second distribution system (step S81), and then moves the process to step S82.

  At this time, the control unit 230 calculates the capacity of the ring buffer 220 necessary for streaming reception of the content data from the information amount (data size) of the content data to be received by the second distribution system. The capacity of the storage area required by participating in the second distribution system is detected.

  Here, the control unit 230 detects the necessary capacity of the ring buffer 220 based on the amount of content data received by the second distribution system. The necessary capacity of the ring buffer 220 may be detected based on the communication speed of the other terminal device 2 that performs streaming distribution.

  Next, in step S82, the control unit 230 performs a process for deleting various information described later shown in FIG. 24, and then moves the process to step S83.

  In step S83, the control unit receives the node information of the connection destination candidate from the connection management device 3, and then moves the process to step S84.

  Here, the control unit 230 transmits a connection destination introduction request to the connection management device 3, whereby the location information (connection information) of the terminal device that is a connection destination candidate in the tree-like hierarchical structure of the second distribution system is transmitted from the connection management device 3. Node information including the destination candidate's IP address and port number) and the communication protocol is received.

  Next, in step S84, the control unit 230 transmits a content data distribution request to the connection destination candidate, thereafter ends the participation process in the second distribution system, and the process is step S19 of the main process shown in FIG. Move to.

(Deleting information)
Next, a process of deleting various information performed by the control unit 230 in the process of participating in the second distribution system shown in FIG. 23 will be described with reference to FIG.

  In the deletion process of various types of information, the control unit 230 determines whether there is a free area for the second distribution system as shown in FIG. 24 (step S91).

  Here, the control unit 230 can sufficiently secure the storage capacity detected in step S81 in the first distribution system / second distribution system storage unit 205b in which the first distribution system storage area 250 is reserved. It is determined whether or not there is a free area (step S91). If it is determined that there is a free area (step S91: Yes), this various information deletion process is terminated, and the process is shown in FIG. 2 The process moves to step S83 of the participation process in the distribution system, and when it is determined that there is no free space (step S91: No), the process moves to step S92.

  In step S92, the control unit 230 performs information deletion processing according to the priority order. Here, the control unit 230 sequentially deletes the information stored in the first distribution system storage area 250 from information that does not hinder the reception of the content data by the first distribution system even if the information is deleted.

  More specifically, the control unit 230 provides a part of the index cache information, catalog information, and node information in the routing table RT in the index table 222 until a sufficient storage capacity can be secured as the second distribution system storage area. The information is deleted sequentially in the order of.

  Then, after performing the process of step S92, the control unit 230 ends the information deletion process in accordance with the priority order, and then moves the process to step S83 of the participation process in the second distribution system shown in FIG. .

And
(Index cache information deletion process 1)
Next, the deletion processing 1 of index cache information with the highest deletion priority in the information deletion processing according to the priority shown in FIG. 24 will be described with reference to FIG. In the index cache information deletion process 1, the control unit 230 deletes all index cache information held by itself.

  In the index cache information deletion process 1, the control unit 230 saves all index cache information in the index table 222 in the first distribution system storage area 250 held by itself in a predetermined area of the hard disk device 203 (step S101). Thereafter, the process proceeds to step S102.

  In step S102, the control unit 230 deletes all index cache information from the first distribution system storage area 250, and then ends the index cache information deletion processing 1 to execute the second distribution shown in FIG. The process proceeds to step S83 of the system participation process.

(Delete processing of index cache information 2)
If the controller 230 does not delete all the index cache information, but only a part of the index cache information is deleted, a sufficient storage capacity can be secured as a storage area for the second distribution system. The index cache information deletion process 2 shown in FIG.

  In this index cache information deletion process 2, the control unit 230 deletes only the index cache information of the content that is not the root terminal device among all the index cache information. Here, two index cache information is stored in the index table 222, and the own device 2 is the root terminal device of the first index cache information and is not the root terminal of the second index cache information. An example will be described.

  In the index cache information deletion process 2, the control unit 230 first stores the variable NUM = 0 in a predetermined storage area in the first distribution system storage area 250 (step S111), and then performs the processing step. Move to S112.

  In step S112, the control unit 230 determines whether or not the number of index cache information currently held is larger than the variable NUM, and determines that the number of index cache information currently held is larger than the variable NUM. The process proceeds to step S113 (step S112: Yes).

  On the other hand, when the control unit 230 determines that the number of index cache information currently held is smaller than the variable NUM, the control unit 230 ends the deletion process 2 of the index cache information, and the process is the second distribution system shown in FIG. The process proceeds to step S83 of the participation process.

  Here, since the number of index cache information currently held by the own device 2 is 2 and is larger than NUM (= 0), the result of determination in step S112 (step S112: Yes), the process proceeds to step S113. Transition.

  In step S113, the control unit 230 determines whether or not the own device 2 is the root terminal device of the NUM + 1-th index cache information, and performs processing when determining that the own device 2 is the root terminal device (step S113: Yes). The process moves to step S116, and if it is determined that it is not the root terminal device (step S113: No), the process moves to step S114.

  Here, since the own device 2 is the root terminal device of the NUM + 1 (0 + 1 = 1) -th index cache information, as a result of the determination in step S113 (step S113: Yes), the processing moves to step S116.

  In step S116, the control unit 230 performs a process (NUM + 1) of incrementing the variable NUM by 1, and then moves the process to step SS112.

  Next, in step S112, the control unit 230 again determines whether or not the number of index cache information currently held is larger than the variable NUM. Here, since the number of index cache information currently held by the own device 2 is 2 and larger than NUM (= 1), the result of determination in step S112 (step S112: Yes), the process proceeds to step S113. To do.

  Next, in step S113, the control unit 230 determines whether or not the own device 2 is the root terminal device of the NUM + 1 (1 + 1 = 2) th index cache information.

  Here, since the own device 2 is not the root terminal device of the NUM + 1 (1 + 1 = 2) -th index cache information, the process proceeds to step S114 as a result of the determination in step S113 (step S113: No).

  In step S114, the control unit 230 performs processing for storing index cache information (second index cache information) in which the device 2 is not a root terminal device in a predetermined area of the hard disk device 203, and then moves the processing to step S115.

  In step S115, the control unit 230 performs a process of deleting the index cache information stored in the hard disk device 203 from the first distribution system storage area, and then moves the process to step S116.

  Next, in step S116, the control unit 230 performs a process of incrementing the variable NUM by 1 (NUM = 1 + 1 = 2), and then moves the process to step S112.

  Next, in step S112, the control unit 230 again determines whether or not the number of index cache information currently held is larger than the variable NUM. Here, since one index cache information currently held by the own device 2 is deleted in step S115, the number of index cache information currently held is 1, which is smaller than the variable NUM. As a result of the determination (step S112: No), the index cache information deletion process 3 is terminated, and the process proceeds to step S83 of the participation process in the second distribution system shown in FIG.

(Index cache information deletion process 3)
Further, the control unit 230 can perform the index cache information deletion process 3 shown in FIG. 27 as a modification example in which all or some of the index cache information is deleted.

  In the index information deletion process 3, the control unit 230 determines the index cache information held by the own device 2 based on the information amount of the index cache information held by the root terminal device of the index cache information. Delete index cache information.

  That is, in the index cache information deletion process 3, as shown in FIG. 27, the control unit stores the variable NUM = 0 in a predetermined area in the first distribution system storage area 250 (step S121). Then, the process proceeds to step S122.

  In step S122, the control unit 230 determines whether or not the currently held index cache information number is larger than the variable NUM, and determines that the currently held index cache information number is larger than the variable NUM. The process moves to step S123 (step S122: Yes).

  On the other hand, when the control unit 230 determines that the number of index cache information currently held is smaller than the variable NUM, the control unit 230 ends the deletion process 3 of the index cache information, and the process is the second distribution system shown in FIG. The process proceeds to step S83 of the participation process.

  In step S123, the control unit 230 performs an information amount acquisition process from the root terminal device, and then moves the process to step S124.

  Here, the control unit 230 determines, from the root terminal device of the index cache information that is the deletion target in the currently held index cache information, the deletion target index cache information that the root terminal device holds. Get the same number of index cache information.

  Next, in step S124, the control unit 230 determines whether the amount of information acquired from the root terminal device is larger than a preset threshold value, and determines that the acquired information amount is larger than the threshold value. If so (step S124: Yes), the process proceeds to step S125. If it is determined that the acquired information amount is smaller than the threshold (step S124: No), the process proceeds to step S127.

  In step S125, the control unit 230 stores the index cache information to be deleted held by the control unit 230 in a predetermined area of the hard disk device 203, and then moves the process to step S126.

  In step S126, the control unit 230 performs indexing information deletion processing for deleting the index cache information stored in the hard disk device 203 from the first distribution system storage area 250, and then moves the processing to step S127.

  In step S127, the control unit 230 performs a process (NUM + 1) of incrementing the variable NUM by 1, and then moves the process to step S122.

(Catalog information deletion process)
If the controller 230 cannot secure a sufficient storage capacity as the second distribution system storage area 251 even if the index cache information is deleted from the first distribution system storage area 250 as described above, the control unit 230 returns to FIG. The catalog information is deleted from the first distribution system storage area 250 by performing the catalog information deletion process shown.

  In the catalog information deletion process, the control unit 230 stores the catalog information stored in the first distribution system storage area 250 in a predetermined area in the hard disk device 203 (step S131), as shown in FIG. Then, all catalog information is deleted from the first distribution system storage area 250 (step S132), and then the catalog information deletion process is terminated, and the process is joined to the second distribution system shown in FIG. Move to.

(Node information deletion process 1)
Further, even if the control unit 230 deletes the index cache information and the catalog information from the first distribution system storage area 250 as described above, the control unit 230 cannot secure a sufficient storage capacity as the second distribution system storage area 251. In this case, a part of the routing table RT is deleted from the first distribution system storage area 250 by performing the node information deletion process 1 shown in FIG.

  In the node information deletion process 1, the control unit 230 performs a process of saving the selected node information in the hard disk device 203 (step S141). Here, the control unit 230 selects the node information to be deleted from the node information in the routing table RT in advance, and deletes the index cache information and the catalog information from the first distribution system storage area 250. When a sufficient storage capacity cannot be secured as the second distribution system storage area 251, the node information selected in advance is stored in the hard disk device 203.

  Next, the control unit 230 deletes the preselected node information from the first distribution system storage area 250 (step S142), and then ends the node information deletion process 1 and the process is shown in FIG. The process proceeds to step S83 of the participation process in the second distribution system.

(Node information deletion process 2)
Further, when part of the routing table RT is deleted, the control unit 230 performs the node information deletion process 2 shown in FIG. 30 in place of the node information deletion process 1, thereby performing the first distribution system use. Part of the node information can be deleted from the storage area 250.

  In the node information deletion process 2, the control unit 230 refers to the routing table RT to determine whether there are sub-tables R1 to R3 (step S151), and determines that there are sub-tables R1 to R3. If so (step S151: Yes), the process proceeds to step S152, and if it is determined that there are no sub-tables R1 to R3 (step S151: No), the node information deletion process 2 is terminated, and the process proceeds to FIG. It moves to step S83 of the participation process to the 2nd delivery system shown.

  In step S152, the control unit 230 performs sub-table deletion processing. Here, the control unit 230 deletes the sub-table R3 in order from the sub-table R3, which is less likely to interfere with reception of the content data by the first distribution system.

  Then, after performing the sub-table deletion process, the control unit 230 ends the node information deletion process 2 and moves the process to step S83 of the process of joining the second distribution system shown in FIG.

  And the control part 230 is memorize | stored in the memory area 250 for 1st delivery systems by processes, such as deletion processing 1-3 of the above-mentioned index cache information, catalog information deletion processing, and node information deletion processing 1-2. The information is deleted, and the area where the deleted information is stored is caused to function as the second distribution system storage area 251.

  As described above, the second distribution system storage area stores (stores) the stream control program 215, the topology management program 216, the ring buffer 220, and the like necessary for receiving content data by the second distribution system. )

(Processing while participating in the second distribution system)
Next, the second distribution system participation process performed by the control unit 230 in step S18 of the main process illustrated in FIG. 17 will be described with reference to FIG.

  In this second distribution system participation process, as shown in FIG. 31, the control unit 230 determines whether or not its own device 2 is disconnected from the second distribution system (step S161). In step S161: Yes, the process proceeds to step S165. If it is determined that the process does not leave (step S161: No), the process proceeds to step S162.

  In step S162, the control unit 230 performs a received content reproduction process for streaming reproduction of the content data stream-received from the terminal device 2 connected to the upstream side in the tree-like hierarchical structure, and then the process proceeds to step S163. Transfer.

  In step S163, the control unit 230 determines whether or not it is connected to a downstream device (the terminal device 2 that is downstream in the tree-like hierarchical structure) and determines that it is connected to a downstream device. The process proceeds to step S164 (step S163: Yes), and when it is determined that it is not connected to a downstream device (step S163: No), this second distribution system participation process is terminated, and the process is illustrated. The process proceeds to step S19 of the main process shown in FIG.

  In step S165, the control unit 230 performs a relay stop request message transmission process to an upstream device. That is, the control unit 230 transmits a message requesting stop of distribution of content data to the own device 2 to the terminal device 2 connected to the upstream side of the own device 2 in the tree-like hierarchical structure. .

  Next, in step S166, the control unit 230 performs a later-described stored information reading process shown in FIG. 32, and then ends this second distribution system participation process, and the process is a step of the main process shown in FIG. Move to S19.

  In addition, since the content distribution apparatus 1 in the second distribution system of the present embodiment is configured to distribute the content data in the broadcast form through one channel, the control unit 230 in the second distribution system participation process, As described above, when it is determined to leave the second distribution system, the stored information is read immediately after the relay stop message is transmitted to the upstream apparatus. When a plurality of types of content data are distributed in the form of broadcast on the channel, and this terminal device 2 is currently receiving a plurality of content data distributed simultaneously on a plurality of channels, it is determined that the terminal device 2 will leave the second distribution system. Thereafter, the following processing is performed.

  That is, if the control unit 230 determines in step S161 shown in FIG. 31 to leave the second distribution system, the control unit 230 stops receiving content data from all channels currently receiving distribution, or a part of the distribution data. It is determined whether to stop only receiving content data from the channel.

  Here, when the control unit 230 determines to stop only the reception of content data from some channels, the control unit 230 performs a process of reducing the area of the ring buffer 220 reserved for the channel for which reception is stopped, and then Then, the process proceeds to step S166 shown in FIG.

  On the other hand, when determining that the reception of the content data from all the channels currently receiving distribution is stopped, the control unit 230 deletes the information stored in the second distribution system storage area 251 and first Processing is performed to make the entire distribution system / second distribution system storage unit 205b usable as the first distribution system storage area 250, and then the process proceeds to step S166 shown in FIG. Process.

(Reading saved information)
Next, the storage information reading process performed by the control unit 230 in step S168 of the second distribution system participation process illustrated in FIG. 31 will be described with reference to FIG.

  In this storage information reading process, the control unit 230 determines whether or not the index cache information is stored in the hard disk device 203 as shown in FIG. 32 (step S171), and the index cache information is stored. If it is determined that the index cache information is not stored (step S171: No), the process proceeds to step S173.

  In step 172, the control unit 230 reads the index cache information stored in the hard disk device 203, stores it again in the first distribution system storage area 250, and then moves the process to step S173.

  In step S173, the control unit 230 determines whether or not the node information is stored in the hard disk device 203. If it is determined that the node information is stored (step S173: Yes), the process proceeds to step S174. If it is determined that the node information is not stored (step S173: No), the process proceeds to step S175.

  In step S174, the control unit 230 reads the node information from the hard disk device 203, stores it again in the first distribution system storage area 250, and then moves the process to step S175.

  In step S175, the control unit 230 determines whether or not catalog information is stored in the hard disk device 203. If it is determined that catalog information is stored (step S175: Yes), the process proceeds to step S176. If it is determined that the catalog information is not stored (step S175: No), the storage information reading process is terminated, and the process proceeds to step S19 of the main process shown in FIG.

  In step S176, the control unit 230 reads the catalog information from the hard disk device 203 and stores it again in the first distribution system storage area. Then, the storage information reading process ends, and the process is shown in FIG. The process proceeds to step S19 of the main process shown.

(Processing corresponding to the message of the second distribution system)
Next, the process corresponding to the message of the second distribution system performed by the control unit 230 in step S20 of the main process shown in FIG. 17 will be described with reference to FIG.

  In the processing corresponding to the message of the second distribution system, the control unit 230 requests that the received message of the second distribution system is a content data relay request from the terminal device 2 connected downstream in the tree-like hierarchical structure. It is determined whether or not the message is a message (step S181). If it is determined that the message is a relay request message (step S181: Yes), the process proceeds to step S182. If it is determined that the message is not a relay message (step S181: No) ) Moves the process to step S183.

  In step S182, the control unit 230 performs streaming distribution of the content data stream-received from the terminal device 2 connected upstream in the tree-like hierarchical structure to the terminal device 2 connected downstream in the tree-like hierarchical structure. The received content relay process is performed, and then the process corresponding to the message of the second distribution system is terminated, and the process proceeds to step S14 of the main process shown in FIG.

  In step S183, the control unit 230 determines whether the received message of the second distribution system is a content data relay stop request message from the terminal device 2 connected downstream in the tree-like hierarchical structure. If it is determined that the message is a relay stop request message (step S183: Yes), the process proceeds to step S184. If it is determined that the message is not a relay stop request (step S183: No), the second distribution system The process corresponding to the message is terminated, and the process proceeds to step S14 of the main process shown in FIG.

  In step 184, the control unit 230 performs a received content relay stop process for stopping streaming relay of content data stream-received from the terminal device 2 connected upstream in the tree-like hierarchical structure, and then the second distribution system. The process corresponding to the message is terminated, and the process proceeds to step S14 of the main process shown in FIG.

  In step S185, the control unit 230 performs another process different from the reception of the content data by the first and second distribution systems, and then ends the process corresponding to the message of the second distribution system, The process moves to step S14 of the main process shown in FIG.

It is a figure showing an example of outline composition of a contents distribution system concerning this embodiment. It is delivery operation explanatory drawing of the 1st delivery system of the content delivery system which concerns on this embodiment. It is a figure which shows an example of a mode that a routing table is produced by DHT. It is a figure which shows an example of the main table in a routing table. It is explanatory drawing which shows a routing table. It is a figure which shows an example of a mode that a terminal device participates in a 1st delivery system. It is a figure which shows an example of a mode that the terminal device holding content data is searched by DHT routing. It is a figure which shows an example of a mode that content data are hold | maintained at a terminal device by DHT routing. It is a figure which shows an example in which a registration message is transmitted to a root terminal device by DHT routing. It is a figure which shows an example of an index table. It is delivery operation explanatory drawing of the 2nd delivery system of the content delivery system which concerns on this embodiment. It is the figure which represented the function of the ring buffer notionally. It is a figure which shows the schematic structural example of a terminal device. It is explanatory drawing which shows the memory area for 1st delivery systems, and the memory area for 2nd delivery systems. It is explanatory drawing which shows the memory area for 1st delivery systems, and the memory area for 2nd delivery systems. It is a flowchart which shows the process in a connection management apparatus. It is a flowchart which shows the main process in a terminal device. It is a flowchart which shows the process corresponding to the message of a 1st delivery system. It is a flowchart which shows the registration process 1 to an index table. It is a flowchart which shows the registration process 2 to an index table. It is a flowchart which shows the registration process 1 to a routing table. It is a flowchart which shows the registration process 2 to a routing table. It is a flowchart which shows the participating process to a 2nd delivery system. It is a flowchart which shows the deletion process of various information. It is a flowchart which shows the deletion process 1 of index cache information. It is a flowchart which shows the deletion process 2 of index cache information. It is a flowchart which shows the deletion process 3 of index cache information. It is a flowchart which shows a catalog information deletion process. It is a flowchart which shows the deletion process 1 of node information. It is a flowchart which shows the deletion process 2 of node information. It is a flowchart which shows a 2nd delivery system participation process. It is a flowchart which shows an information reading process. It is a flowchart which shows the process corresponding to the message of a 2nd delivery system.

Explanation of symbols

S content distribution system 1 content distribution device 2 terminal device 3 connection management device 4 content input device 5 contact destination introduction device 6 network 130, 230, 330, 430, 530 control unit 230 control unit 203 hard disk device 205 main storage device 205b first Distribution system / second distribution system storage unit 250 First distribution system storage area 251 Second distribution system storage area

Claims (16)

In a state where other terminal devices that hold the content data based on a download request for content data from one terminal device participate in a first distribution system that distributes the content data, among a plurality of terminal devices, In a terminal device capable of participating in a second distribution system that performs streaming distribution of content data in broadcast form from a content distribution device to a terminal device,
A storage area reserved for the first distribution system when participating in the first distribution system;
When participating in the second distribution system while participating in the first distribution system, a part of the storage area reserved for the first distribution system is caused to function as a storage area for the second distribution system. Information management means;
The terminal device characterized by having. Storage capacity detecting means for detecting the capacity of the storage area required by participating in the second distribution system;
Whether the information management unit causes a part of the storage area reserved for the first distribution system to function as the storage area for the second distribution system according to the detection result of the storage capacity detection unit. The terminal device according to claim 1, wherein the terminal device is determined. In the first distribution system, a plurality of types of content data are distributed and held in a plurality of terminal devices connected via a network, and other terminals holding the content data corresponding to the download request A distribution system in which the content data is distributed from a device to a terminal device that has transmitted the download request;
Associating location information of another terminal device that is participating in the first distribution system and holding the content data with content identification information for identifying the content data held by the other terminal device Content holding terminal information receiving means for receiving the received content holding terminal information,
The information management means includes
Storing the content holding terminal information received by the content holding terminal information receiving means in a storage area reserved for the first distribution system;
When participating in the second distribution system while participating in the first distribution system, the content holding terminal information stored in the storage area reserved for the first distribution system is deleted, and the content holding terminal The terminal device according to claim 1 or 2, wherein an area storing information functions as a storage area for the second distribution system. An information amount acquisition means for acquiring an information amount of the content holding terminal information managed by the terminal device from a terminal device managing the content holding terminal information to be deleted;
The information management unit obtains the content holding terminal information to be deleted from the storage area reserved for the first distribution system when the amount of information acquired by the information amount acquisition unit exceeds a predetermined threshold. The terminal device according to claim 3, wherein the terminal device is deleted. The information management means includes
The information amount acquisition unit acquires the information amount of the content holding terminal information regarding a plurality of types of content data, and sequentially deletes the content holding terminal information from the acquired plurality of types of information amount in descending order. The terminal device according to claim 4. The information management means includes
In the storage area reserved for the first distribution system, the list information of the content data that can be downloaded at present is stored,
When participating in the second distribution system while participating in the first distribution system, the list information is deleted from the storage area reserved for the first distribution system, and the list information is stored. The terminal device according to claim 1, wherein the terminal device functions as a storage region for the second distribution system. The information management means includes
Storing other terminal information including terminal identification information for identifying other terminal devices and location information of the other terminal devices in a storage area reserved for the first distribution system;
When participating in the second distribution system in a state of participating in the first distribution system, at least a part of the other terminal information is deleted from the storage area reserved for the first distribution system, and the other The terminal device according to claim 1, wherein an area in which terminal information is stored is caused to function as a storage area for the second distribution system. The information management means includes
In the storage area reserved for the first distribution system,
Associating location information of another terminal device that is participating in the first distribution system and holding the content data with content identification information for identifying the content data held by the other terminal device Storing the content holding terminal information and the list information of the content data currently available for download,
Storing terminal identification information for identifying other terminal devices and other terminal information including location information of the other terminal devices;
When participating in the second distribution system in a state of participating in the first distribution system, the content holding terminal information and the list information are deleted from the storage area reserved for the first distribution system, The terminal device according to claim 1, wherein a part of the other terminal information is deleted. In the information stored in the storage area reserved for the first distribution system,
The priority of deletion by the information management means is:
The terminal device according to claim 8, wherein the content holding terminal information, the list information, and the other terminal information are in this order. Having a participating terminal number detecting means for detecting the number of terminal devices participating in the first distribution system;
The information management means, when the number of terminal devices detected by the participating terminal number detection means exceeds a predetermined threshold value, a part of a storage area reserved for the first distribution system in the second distribution The terminal device according to claim 1, wherein the terminal device functions as a storage area for the system. Comprising other storage means for storing information to be deleted from the storage area reserved for the first distribution system;
When participating in the second distribution system while participating in the first distribution system,
The information management means includes
After storing a part of the information stored in the first distribution system in the other storage unit, an area in which the information stored in the other storage unit is stored is stored for the second distribution system. Function as an area,
11. The information stored in the other storage means after leaving the second distribution system is stored again in a storage area reserved for the first distribution system. The terminal device according to claim 1. The storage area reserved for the second distribution system includes a ring buffer for temporarily storing content data stream-received by the second distribution system,
The information management means includes
When participating in the second distribution system while participating in the first distribution system,
The terminal device according to any one of claims 1 to 11, wherein a part of a storage area reserved for the first distribution system is caused to function as the ring buffer. Receiving speed detecting means for detecting a receiving speed when content data is received by the second distribution system;
The information management means includes
A storage area reserved for the first distribution system according to the reception speed acquired by the reception speed detection means when participating in the second distribution system in a state of participating in the first distribution system. The terminal device according to claim 1, wherein an area that functions as a storage area for the second distribution system is expanded or reduced. A first distribution system in which another terminal device holding the content data distributes the content data based on a download request for content data from one terminal device, and the content distribution device to the terminal device among a plurality of terminal devices A content delivery system having a second delivery system for streaming delivery of content data in broadcast form,
The terminal device
A storage area reserved for the first distribution system when participating in the first distribution system;
When participating in the second distribution system while participating in the first distribution system, a part of the storage area reserved for the first distribution system is caused to function as a storage area for the second distribution system. Information management means;
A content distribution system comprising:   The program for functioning a computer as each means in the terminal device in any one of Claims 1-13. In a state where other terminal devices that hold the content data based on a download request for content data from one terminal device participate in a first distribution system that distributes the content data, among a plurality of terminal devices, An information management method in a terminal device capable of participating in a second distribution system that performs streaming distribution of content data from a content distribution device to a terminal device in broadcast form,
Securing a storage area for the first distribution system when participating in the first distribution system;
Deleting a part of information stored in a storage area reserved for the first distribution system when participating in the second distribution system in a state of participating in the first distribution system;
Causing the storage area reserved for the first distribution system in which the deleted information is stored to function as a storage area for the second distribution system;
An information management method characterized by comprising:

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