JP2006065516A - Distribution load balancer, distribution server, content distributing system, distribution load balancing method, distribution load balancing program and computer-readable recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a distribution server for efficiently distributing contents to a user terminal. <P>SOLUTION: A distribution server main body 2a is provided with an own-server load status monitoring part 11 for predicting a distribution load in the distribution server based on the log of access from the user terminal to the distribution server to be monitored and a distribution server determination part 12 for determining to distribute the contents from any distribution server other than the distribution server 2 when it is predicted that a distribution load to the distribution server 2 may be increased by the own-server load status monitoring part 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides a distribution load distribution device, a distribution server, a content distribution system, and a distribution load distribution for distributing contents efficiently by distributing the load on the distribution server when distributing contents from a distribution server to a plurality of user terminals. The present invention relates to a method, a distribution load distribution program, and a computer-readable recording medium.

  In recent years, information such as video and music can be viewed at home by accessing a server device via a network. Since video data and music data are large-capacity contents, it is necessary to efficiently transmit them from the server device to the user terminal device. For this purpose, it is necessary to construct a content distribution system that can cope with a case where content distribution requests from users are concentrated on the server device.

  In other words, when content distribution requests from users are concentrated on the server device, the distribution load on the server device increases, and content distribution on the server device may become unsatisfactory. In addition, the waiting time from when the distribution request is made until the content is actually distributed becomes long, which may annoy the user.

As a content distribution system corresponding to the problem that may occur when distribution requests are concentrated in this way, the one described in Patent Document 1 can be cited. In the content distribution system described in Patent Document 1, storage control of content is performed between a video server and another video server when the number of content transmissions or the number of predictable accesses exceeds a corresponding threshold value. , Dynamic distribution of content.
JP 11-98446 A (published on April 9, 1999)

  However, Patent Document 1 does not specifically describe how to predict the number of accesses. Therefore, if the number of accesses is wrongly predicted, content distribution will not be performed from other video servers even if the number of accesses is large, or content distribution will be performed from other video servers even if the number of accesses is not so large. In some cases, content distribution cannot be performed efficiently.

  The present invention has been made in view of the above-described conventional problems, and is a distribution load distribution device, distribution server, content distribution system, distribution load distribution method, and distribution load distribution program that can efficiently distribute content to user terminals. And a computer-readable recording medium.

  In order to solve the above-described problem, the distribution load distribution apparatus of the present invention distributes the distribution load of the content distribution server, and the distribution load distribution device is configured to distribute the distribution load based on the access log from the user terminal to the distribution server to be monitored. A load state monitoring unit that predicts a distribution load on the server, and when the load state monitoring unit predicts that the distribution load to the distribution server will be high, it decides to distribute content from a distribution server other than the distribution server. And a distribution server determination unit.

  The distribution load distribution method according to the present invention is a method for distributing a distribution load in a content distribution server, wherein the distribution load in the distribution server is predicted based on a log of access to the monitored distribution server. And a second step of deciding to distribute content from a distribution server other than the distribution server when the distribution load on the distribution server is predicted to increase due to the first step.

  According to the above configuration, when it is predicted by the load state monitoring means or the first step that the distribution load in the monitoring target distribution server (own distribution server) will be increased, the distribution server determination means or the second step is performed by a device other than the own distribution server. It is determined that the content is distributed from the distribution server (other distribution server). Therefore, since the content can be distributed from the other distribution server before the distribution load in the own distribution server becomes an overload state, the content can be stably distributed to the user terminal.

  In addition, in the load state monitoring means or the first step, the distribution load is predicted based on the access log for the own distribution server, so that the future distribution load can be appropriately predicted.

  Therefore, in the distribution server determination means or the second step, it is possible to appropriately determine whether or not to distribute the content from another distribution server, so that the content can be distributed to the user terminal more efficiently.

  Further, the load state monitoring means determines a period at which a content distribution request that can permit distribution of content from the monitored distribution server is transmitted to the distribution server, the number of channels used for content distribution, and the content as a user. It is preferable to predict the distribution load in the distribution server using a threshold value set based on the time for transfer to the terminal.

  In other words, the number of terminals that can simultaneously distribute content from a certain distribution server is determined by transmitting the content distribution request that can permit distribution of content, the number of channels used for content distribution, and the content to the terminal side. It can be calculated from the time required for

  Therefore, according to the above configuration, since the load on the distribution server is predicted by setting a threshold based on the above three parameters, it is possible to predict an appropriate distribution load. Therefore, the content can be distributed to the user terminal more efficiently.

  The distribution server of the present invention includes the distribution load distribution apparatus having the above-described configuration. According to the above configuration, since the distribution load distribution device of the present invention is provided in the distribution server, it is possible to efficiently distribute the content to the user terminal.

  Furthermore, the distribution server of the present invention preferably includes other server load state monitoring means for monitoring the content distribution load in the other distribution server.

  According to the said structure, the content delivery load in another delivery server is monitored by the other server load state monitoring means. Therefore, when the distribution server determining unit determines to distribute the content using the other distribution server, it is possible to determine whether the distribution server distributes the content in consideration of the distribution load on the other distribution server.

  That is, when the distribution load is determined to be high in the other distribution server by the other server load state monitoring means, the content is not distributed from the distribution server, and the content is distributed using another distribution server. can do. Therefore, the content can be distributed to the user terminal more efficiently.

  Furthermore, it is preferable that the distribution server of the present invention distributes content to each user terminal using a band allocated to each of the plurality of user terminals.

  According to the above configuration, since the band used for content distribution is individually assigned to each user terminal, the content can be distributed in a band fixed to each user terminal. Therefore, the content can be distributed to the user terminal in a more stable communication state.

  Furthermore, the content distribution system of the present invention includes a distribution load distribution device of the present invention, a plurality of distribution servers including at least one distribution server whose distribution load is predicted by a load state monitoring unit of the distribution load distribution device, And a plurality of user terminals to which contents are distributed from any of a plurality of distribution servers.

  In addition, the content distribution system of the present invention includes a plurality of distribution servers including the distribution server of the present invention, and a plurality of user terminals to which content is distributed from any of the plurality of distribution servers. Also good.

  According to the above configuration, since the distribution load distribution apparatus or distribution server according to the present invention is provided in the content distribution system, the content can be efficiently distributed to a plurality of user terminals.

  Furthermore, the content distribution system of the present invention preferably includes a secondary distribution server that assists the content distribution by the distribution server.

  According to the above configuration, since the content distribution by the distribution server is assisted by the sub-distribution server, the distribution load on the distribution server is reduced, and the content can be distributed more efficiently from the distribution server.

  Furthermore, the content distribution system of the present invention preferably includes a reception device that receives content distribution requests from a plurality of user terminals in the content distribution system.

  According to the above configuration, content reception requests from the user terminal can be centrally managed by the reception device, and content distribution requests made to a plurality of distribution servers can be made to this reception device. .

  Therefore, it is possible to prevent content distribution requests from being concentrated on a specific distribution server and increase the load on the distribution server, and to distribute content to user terminals more efficiently.

  Note that the distribution load distribution program for causing a computer to execute the above distribution load distribution method can obtain the same effects as the distribution load distribution method of the present invention using a computer. Further, by storing the distribution load distribution program in a computer-readable recording medium, the distribution load distribution program can be executed on any computer.

  According to the present invention, content can be distributed from another distribution server before the distribution load in the self-distribution server becomes an overload state, so that the content can be stably distributed to the user terminal. .

  In addition, since the load state monitoring means predicts the distribution load based on the access log for the self distribution server, the future distribution load can be appropriately predicted. Therefore, the distribution server determination unit can appropriately determine whether or not to distribute the content from another distribution server, so that the content can be distributed to the user terminal more efficiently.

[1. (Basic configuration of content distribution system)
A basic configuration of a content distribution system using a distribution server according to an embodiment of the present invention (hereinafter simply referred to as the present content distribution system) will be described. First, an outline of the content distribution system will be described with reference to FIG.

  As shown in FIG. 2, the content distribution system includes a content server 1, a plurality of distribution servers 2, and a plurality of user terminals 3.

  The content server 1 stores content to be distributed and transmits it to the distribution server 2... As the content, such as moving image data, music data, still image data, or application execution data. Anything can be used as long as it can be transmitted via. The network includes satellite communication network, Internet, LAN (Local Area Network), WAN (Wide Area Network), FTTH (Fiber To The Home), CATV (Community Antenna TeleVision), XDSL (Digital Subscriber Line), ISDN ( It includes various wireless / wired communication lines such as Integrated Services Digital Network) and public telephone network.

  The distribution server 2 relays the content transmitted from the content server 1 and transmits it to the user terminals 3 through the same network as between the content server 1 and the distribution server 2. In FIG. 2, among the plurality of distribution servers 2..., A distribution server that is typically in charge of content transmission to the user terminals 3. The distribution server that assists the content transmission performed by the main distribution server is surrounded by the framework of the “auxiliary distribution server”.

  The “main distribution server” and the “auxiliary distribution server” have the relationship described below. That is, in this content distribution system, when content distribution requests from the user terminals 3 to the main distribution server are concentrated and it is predicted that the load on the server will increase, the content will be distributed using another auxiliary distribution server. It transmits to the user terminal 3. One feature of the content distribution system is that the load on the main distribution server is predicted. Details of this feature point will be described later.

  Moreover, the relationship between the distribution server 2 and the user terminal 3 arbitrarily extracted one by one from the plurality of distribution servers 2 and the plurality of user terminals 3 and the content server 1 will be described with reference to FIG.

  As shown in FIG. 3, the content server 1 includes a content server main body 1a and a content storage unit 1b. The distribution server 2 includes a distribution server body 2a and a content storage unit 2b. How each block constituting the content distribution system exchanges information will be described with reference to the time sequence of FIG.

  As shown in FIG. 4, first, a content distribution request is transmitted from the user terminal 3 to the distribution server body 2a of the distribution server 2 (step 1, hereinafter, step is simply referred to as S). If distribution requests from other user terminals 3 are concentrated in the distribution server 2 and the content cannot be transmitted to the user terminal 3, the distribution server body 2a sends a message indicating that the content distribution cannot be permitted to the user terminal. 3 (S2).

  The processes of S1 and S2 are repeated until the distribution server 2 has a low load and content distribution to the user terminal 3 is permitted. Then, while the processes of S1 and S2 are repeated, the distribution server main body 2a accumulates information regarding the user who has not been able to distribute the content, that is, information regarding the user of the user terminal 3 that has transmitted the disapproval message at S2. S3).

  Thereafter, a message to the effect that content distribution is accepted is transmitted from the distribution server 2 to the user terminal 3 (S4). When this approval message is received, a message (content acquisition request) requesting acquisition of content is transmitted from the user terminal 3 to the distribution server body 2a (S5).

  When the distribution server body 2a receives the content acquisition request from the user terminal 3, the distribution server body 2a transmits the content acquisition request to the content server body 1a (S6). When receiving the content acquisition request from the distribution server main body 2a, the content server main body 1a searches for and extracts the requested content from the content storage unit 1b (S7). Then, the content server main body 1a transmits the content extracted in S7 to the distribution server main body 2a (S8).

  The distribution server body 2a temporarily stores the content transmitted from the content server body 1a in the content storage unit 2b, and then transmits it to the user terminal 3 (S9).

  By stepping on S1 to S9 described above, the content is finally distributed from the content server 1 to the user terminal 3.

[2. Distribution server body configuration and processing flow]
Next, details of the configuration of the distribution server body 2a will be described. As shown in FIG. 1, the distribution server main body 2 a includes a user content use receiving unit 4, a distribution control information transmission / reception unit 5, a user information storage unit 6, a content search / acquisition unit 7, and a content information output unit 8. A content related information presentation unit 9, a content distribution unit 10, a local server load state monitoring unit (load state monitoring unit) 11, a distribution server determination unit (distribution server determination unit) 12, and another server load state monitoring unit (Other server load state monitoring means) 13.

  The distribution server main body 2a is provided with each of the above blocks, thereby monitoring the access load from the user terminal to itself and distributing the content from itself according to the load or distributing the content from other servers. It is possible to determine whether to deliver. Hereinafter, the processing procedure and the function of each block in the distribution server body 2a will be described with reference to the flowchart of FIG.

  First, as shown in FIG. 5, user access for content use is performed by the user content use reception unit 4 (S11). Furthermore, in S11, user authentication processing is also performed by the user content use receiving unit 4. As shown in FIG. 1, the user authentication process in S <b> 11 is performed by confirming whether the ID of the user who performed the access is a regular one registered in the user information storage unit 6. The user information storage unit 6 stores a content ID indicating an index of content distributed to the user, and user access information indicating a log that the user has accessed the distribution server in the past.

  Thereafter, as shown in FIG. 1, the content search / acquisition unit 7 searches the content storage unit 1b (see FIG. 3) of the content server 1 for the content that can be used by the user, and acquires the content on the distribution server 2 side. . The content acquired by the content search / acquisition unit 7 is stored in the content storage unit 2b (see FIG. 3) of the distribution server 2.

  Further, the content information output unit 8 extracts content related information indicating the title, reproduction time, creation time, distribution source, and the like of the content acquired by the content search / acquisition unit 7, and the content related information presentation unit 9 Output to. Upon receiving this content-related information, the content-related information presentation unit 9 presents the content information to the user terminal via the distribution control information transmission / reception unit 5. This content information presentation processing corresponds to the processing of S12 in the flow of FIG.

  After the process of S12, as shown in FIG. 5, the distribution control information transmission / reception unit 5 determines whether or not there is a content distribution request (S13). The process of S13 is performed, for example, by determining in the distribution control information transmission / reception unit 5 whether or not the user has clicked the content distribution button displayed on the screen of the user terminal 3. When it is determined in S13 that there is no content distribution request, the process returns to S12 again to present content information.

  If it is determined in S13 that there is a content distribution request, the distribution control information transmitting / receiving unit 5 determines whether or not to respond to the content distribution request (S14). The determination in S14 is made by determining whether or not the current number of content users exceeds a predetermined threshold value. As this predetermined threshold value, it is possible to use an upper limit value p1 (details will be described later) of the number of distribution requests that allow stable distribution of content.

  When it is determined in S14 that the content distribution request is satisfied, the distribution control information transmission / reception unit 5 transmits a notification to the user terminal 3 to permit distribution of the content (S15). On the other hand, when it is determined in S14 that the content distribution request is not satisfied, the distribution control information transmitting / receiving unit 5 notifies the user terminal 3 that the content cannot be distributed (S16).

  After S15 or S16, the process proceeds to the content distribution request status monitoring step performed by the own server load status monitoring unit 11 (S17). That is, in S17, the number of content distribution requests to the distribution server (hereinafter referred to as the self distribution server) provided by the own server load state monitoring unit 11 and the number of user terminals that rejected the content distribution request. Is recorded. Further, after S17, the content distribution request status for the user is stored in the user information storage unit 6 as user access information in S18 (S18).

  Then, the own server load state monitoring unit 11 calculates the load state of the own delivery server, that is, grasps the number of content delivery requests to the own delivery server at the current time, and predicts future content delivery requests ( S19). The load state calculation procedure by the own server load state monitoring unit 11 will be described later.

  Further, for convenience of explanation, the processing of S17 to S19 is described to be executed after the processing of S15 or S16, but it is not always necessary. That is, the processing of S17 to S19 may be executed constantly regardless of the processing of S15 and S16. Further, the processes of S17 to S19 are not necessarily executed in this order.

  Moreover, as shown in FIG. 5, the process of S20-S22 demonstrated below is performed in parallel with the process of S11-S19. That is, in S20, the load status of a server other than the distribution server in which the other server load state monitoring unit 13 is provided (hereinafter referred to as another distribution server) is monitored. Furthermore, in S21, the load status of the other delivery server is accumulated in the other server load status monitoring unit 13, and then the load status of the other delivery server is calculated in S22.

  The monitoring procedure of the load status of the other distribution server performed in S20 to S22 is preferably executed by the same procedure as the monitoring procedure of the load status for the own distribution server, but it is not always necessary. For example, the load status of the other distribution server may be monitored by simply determining whether or not there is a content distribution request to the other distribution server. Further, the load status monitoring procedure performed in S20 to S22 may be omitted.

  After the load states of the local distribution server and the other distribution servers are calculated in S19 and S22, the distribution server determination unit 12 determines whether to distribute the content using the local distribution server (S23). . Details of the determination procedure in S23 will be described later. In addition, when S22 is abbreviate | omitted, if the load state of the self delivery server is calculated in S19, what is necessary is just to perform the process of S23.

  When it is determined in S23 that the content is distributed using the self-distribution server, the distribution control information transmitting / receiving unit 5 indicates that the self-distribution server can be distributed to the user terminal 3 (S24).

  After S24, the distribution control information transmitting / receiving unit 5 determines whether or not there is a content distribution request from the user (S25). The process of S25 is performed by, for example, the content from the self-distribution server by an operation such as the user pressing the OK button in response to a message that the content is distributed from the self-delivery server displayed on the screen of the user terminal 3. This is done by determining whether the user has agreed to be delivered.

  If it is determined in S25 that there is a content distribution request from the user, the content distribution unit 10 distributes the content to the user terminal 3 (S26).

  On the other hand, when it is determined in S23 that the content is distributed using the other distribution server instead of the own distribution server, the other distribution server presents itself to the user terminal 3 as a server capable of content distribution (S27). Thereafter, the other distribution server determines whether or not there is a content distribution request from the user terminal 3 (S28). If it is determined that there is a request, the other distribution server distributes the content to the user terminal 3. (S29).

  After the content distribution process in S26 or S29 is completed, or when it is determined in S25 or S28 that there is no content distribution request, the distribution control information transmission / reception unit 5 determines whether or not to end the content use. Performed (S30). The determination in S30 is, for example, using the distribution control information transmission / reception unit 5 to display a message such as “Do you want to finish using the content?” On the user terminal 3, and the user presses the OK button for the display. This is realized by determining whether or not the agreement is made by the operation such as.

  By stepping on the above-described S11 to S30, a series of procedures until the content is distributed from the distribution server 2 to the user terminal 3 is completed.

[3. Regarding load status monitoring and distribution server judgment)
Next, the load state calculation procedure by the own server load state monitoring unit 11 executed in S19 of FIG. 5 and the details of the determination procedure by the distribution server determination unit 12 executed in S23 will be described.

  First, the inventors examined the relationship between the number of content distribution requests from the user terminal to the distribution server and the waiting time (delivery start waiting time) from when the distribution request is made until content distribution is started. . As a result, the relationship shown in the graph of part (a) in FIG. 6 could be obtained.

  As shown in part (a) of FIG. 6, the distribution start waiting time increases so as to draw a gentle slope as the number of distribution requests increases until the number of distribution requests reaches a certain value p1. On the other hand, the inventors considered that when the number of distribution requests exceeds p1, the distribution start waiting time increases with a steep slope corresponding to the increase in the number of distribution requests.

  That is, until the number of content distribution requests to the distribution server reaches p1, the number of user terminals making distribution requests is relatively small as shown in part (b) of FIG. It can be said that the content can be distributed to each of the user terminals (n) and is in a “stable distribution” state in which only the content distribution to the user terminals (n + 1) is not possible.

  On the other hand, when the content distribution request to the distribution server exceeds p1, as shown in part (c) of FIG. 6, there are a large number of user terminals making content distribution requests, and the user terminal (1) Only content distribution is performed, and it can be said that the user terminals (m), (m + 1), and (m + 2) are in an “overload” state in which content distribution cannot be performed.

  From the relationship between the distribution waiting time and the number of distribution requests obtained in this way, in the load state calculation step according to S19 in FIG. 5, the own server load state monitoring unit 11 sets the number of distribution requests at the current time to p1. It is determined whether or not the number of distribution requests exceeds p1.

  If the number of distribution requests at the current time does not exceed p1, or if it is not expected to exceed p1, distribution server determination unit 12 distributes content using its own distribution server in S23 of FIG. Decide what to do. When the number of distribution requests at the current time exceeds p1, or when the number of distribution requests is predicted to exceed p1 after a certain amount of time has elapsed from the current time, the distribution server determination unit 12 It is decided to distribute the content from other distribution servers without using.

  Note that the prediction regarding whether or not the number of distribution requests exceeds p1 can be realized by referring to the distribution request status of the content stored in the user information storage unit 6 (see FIG. 1) by the own server load state monitoring unit 11. It is. That is, the user information storage unit 6 stores user access information indicating a log that the user has accessed the distribution server in the past. In this user access information, since the number of user distribution requests in the past and the number of rejected requests are recorded, the own server load state monitoring unit 11 refers to the information, and the current number of distribution requests and rejection By comparing the number with the past, it can be determined whether the number of distribution requests will decrease or increase.

  Here, how to determine the value of p1 which is a threshold value for determining whether or not to perform distribution by the own distribution server will be described. The value of p1 is basically calculated from the relationship between the time required for transferring the content to the user terminal, the time for using the content, and the waiting time until the next content can be used. Furthermore, the value of p1 can be calculated from the number of accesses to the distribution server within a certain time.

  Further, in the calculation procedure of p1 described below, the basic concept is that the next content cannot be used unless a certain time interval is provided, and the content use waiting time is set as a parameter for calculating p1. is doing. On the other hand, in the past, such a threshold that takes into account the use waiting time has not been set, and even if the user can distribute the content if waiting for a certain time, the distribution server is overloaded. It was judged to be in a state.

  However, according to the present embodiment, since p1 is set in consideration of the use waiting time, it is determined that the distribution server is not overloaded even in such a situation.

  With reference to FIG. 7, an example of a procedure for determining the value of p1, which is a threshold value for determining whether or not to perform distribution by the own distribution server, will be described. FIG. 7 is a diagram showing the relationship between time and bandwidth related to content distribution in one channel.

  As shown in FIG. 7, the time from when the user accesses the distribution server 2 via the user terminal 3 until the content is actually distributed is the access time T0, the distribution time T1, the accumulation time T2, and the browse time. It can be classified into T3 and waiting time T4. The explanation about each time is as follows.

Access time T0: Time from when the user accesses the distribution server 2 to make a content distribution request until the distribution server 2 responds to the access. Distribution time T1: Necessary for transferring the content to the user terminal 3. Accumulation time T2: Time for accumulating the content transferred to the user terminal 3 at the user terminal 3 Browse time T3: Time for browsing the transferred content on the user terminal 3 Waiting time T4: Already distributed Wait time from the browsing of the received content until the next delivery request that allows the content delivery.

  When T1 + T2 + T3 + T4 = Tsum, it can be said that the time indicated by Tsum is a period in which one content is distributed to one user terminal (one content usage time). Therefore, the number of users who can simultaneously distribute content on one channel is indicated by Tsum / T1.

  Therefore, if the number of channels used between the distribution server 2 and the user terminal 3 is k, the number of users who can simultaneously distribute content on k channels is indicated by k × Tsum / T1. It is. Therefore, by setting p1 = k × (Tsum / T1 + α), it is possible to make p1 function as a threshold value for determining whether or not to perform distribution by the own distribution server. Α is an arbitrary integer.

  In addition to the procedure for calculating p1 using the distribution time T1, it is also possible to calculate p1 using the number of accesses from the user terminal to the distribution server within a certain time. That is, the number of accesses from the user terminal within one content usage time indicated by Tsum is managed as access information stored in the user information storage unit 6 (see FIG. 1). Note that the number of accesses managed in this way may be the number of accesses from the same user or the number of accesses from different users.

  Then, the distribution request number (access number) when the load state of the distribution server shifts from the stable distribution state to the overload state is grasped from the accumulated access information, and the distribution request number is set to p2. Then, p1 may be calculated from p2 as p1 = k × (p2 + α). Note that k is the number of channels, and α is an arbitrary integer.

[4. Bandwidth guaranteed transmission)
In the content distribution between the distribution server 2 and the user terminal 3 and the content distribution between the content server 1 and the distribution server 2 in the above configuration, data transmission is performed with a guaranteed transmission band in order to perform data transmission more stably. It is preferable. This band guaranteed transmission will be described below.

  As shown in FIG. 8, content is distributed using the bandwidth BW1 between the content server 1 and the distribution server 2, and content is distributed using the bandwidth BW2 between the distribution server 2 and the user terminals 3. Suppose that

  When the number of simultaneous accesses is x, the band BW1 is divided into x channels 1 to x, and the band BW1 / x is assigned to each channel. Similarly, the band BW2 is divided into x channels 1 to x, and the band BW2 / x is assigned to each channel.

  Furthermore, by assigning one channel to each user terminal 3, the transmission band assigned to each user terminal 3 can be fixed. Thereby, the content can be stably distributed to each user terminal 3.

  Of course, since the bandwidth BW1 is allocated to x channels 1 to x between the content server 1 and the distribution server 2, when distributing content from the content server 1 to the plurality of distribution servers 2, each distribution server 2 Content can be distributed stably.

  Also, in order to transmit various information (content acquisition request, etc.) from the distribution server 2 to the content server 1, and the bandwidth BW3 for transmitting various information (content distribution request, etc.) from each user terminal 3 to the distribution server 2. Similarly to the bands BW1 and BW2, the band BW4 can be divided into x channels to realize stable information communication.

[5. (Modification)
Hereinafter, in addition to the content distribution system having the above-described configuration, some configurations of a content distribution system to which the present invention can be applied will be described.

(5-1. Configuration without Content Server and Configuration with Sub-Distribution Server)
In the content distribution system to which the present invention is applicable, it is possible not to provide a content server. That is, as shown in FIG. 9A, by storing in advance the content to be distributed to the user terminal 3 in the content storage unit 2b of the distribution server, the same function as the content storage unit of the content server is achieved. The content storage unit 2b can be secured.

  In FIG. 9A, for convenience of explanation, only one set of the distribution server main body 2a and the content storage unit 2b is illustrated, but actually, a plurality of distribution servers are connected on the network, and these are illustrated. Distribution of content is distributed among a plurality of distribution servers that are not performed and the distribution server main body 2a illustrated in the same manner as in the content distribution system described above. This is illustrated in FIGS. 9 (b), 9 (c), 10 (a) to 10 (d), 11 (a) to 11 (d), and 12 (a) to FIG. The same applies to the configuration of 12 (d).

  Further, as shown in FIG. 9B, a sub delivery server 14 may be provided. The sub-distribution server 14 is provided to assist the distribution of contents of the distribution server body 2a when the distribution server body 2a is overloaded due to an increase in content distribution requests to the distribution server body 2a. It is. That is, in the content distribution system shown in FIG. 9B, it can be said that the content distribution is distributed between the distribution server main body 2a and the sub distribution server 14.

  In FIG. 9B, the distribution server main body 2a and the sub-distribution server 14 are described as being provided in a one-to-one relationship. However, the configuration is not necessarily limited to this. The distribution server main body 2a and the sub distribution server 14 may be provided in a one-to-many relationship or may be provided in a many-to-one relationship. This is the same for all of the content distribution systems described below provided with the secondary distribution server 14.

  Further, as shown in FIG. 9C, instead of omitting the content server main body 1a and the content storage unit 1b, the content to be distributed is stored in advance in the content storage unit 2b as in the configuration of FIG. 9A. On the other hand, a sub distribution server 14 may be provided.

(5-2. Configuration in which reception device is provided independently of distribution server)
Furthermore, in the content distribution system to which the present invention can be applied, the receiving device 15 can be provided independently of the distribution server 2 as shown in FIG. The reception device 15 has the same function as the user content use reception unit 4 and / or the distribution control information transmission / reception unit 5 (see FIG. 1) in the distribution server body 2a, that is, user access and content distribution requests from a plurality of terminals. It has a function to accept.

  When the reception device 15 is provided in the content distribution system as shown in FIG. 10A, at least one of the user content use reception unit 4 and the distribution control information transmission / reception unit 5 may be omitted from the distribution server 2. it can. For convenience of explanation, FIG. 10A shows that the distribution server 2 and the receiving device 15 are provided in a one-to-one relationship, but the configuration is not necessarily limited to this. The distribution server 2 and the receiving device 15 may be provided in a one-to-many relationship or may be provided in a many-to-one relationship. This is the same for all of the content distribution systems described below provided with the receiving device 15.

  Further, in the content distribution system provided with the accepting device 15, as shown in FIG. 10B, the configuration of FIG. 9A is the same as that of FIG. 9A instead of omitting the content server body 1a and the content storage unit 1b. The content to be distributed may be stored in advance in the content storage unit 2b.

  Furthermore, as shown in FIG. 10C, the content distribution system to which the present invention is applicable may include the receiving device 15 and the sub distribution server 14 at the same time. Of course, as shown in FIG. 10 (d), in the content distribution system having the receiving device 15 and the sub-distribution server 14 at the same time, the content server main body 1a and the content storage unit 1b are omitted and distributed to the content storage unit 2b. The content to be stored may be stored in advance.

(5-3. Configuration in which the monitoring device is provided independently of the distribution server)
Furthermore, in the content distribution system to which the present invention is applicable, a monitoring device (distribution load distribution device) 16 can be provided independently of the distribution server 2 as shown in FIG. The monitoring device 16 is configured such that the own server load state monitoring unit 11, the distribution server determining unit 12, and the other server load state monitoring unit 13 (see FIG. 1) in the distribution server body 2a are independent of the distribution server body 2a. That is, it has a function of monitoring the load state of the server itself and other servers and determining from which server content should be distributed.

  When the monitoring device 16 is provided in the content distribution system as shown in FIG. 11A, the distribution server 2 starts the own server load state monitoring unit 11, the distribution server determination unit 12, and the other server load state monitoring unit 13. Can be omitted. For convenience of explanation, FIG. 11A shows that the distribution server 2 and the monitoring device 16 are provided in a one-to-one relationship, but the configuration is not necessarily limited to this. The distribution server 2 and the monitoring device 16 may be provided in a one-to-many relationship or may be provided in a many-to-one relationship. This is the same for all of the content distribution systems described below provided with the monitoring device 16.

  Further, in the content distribution system provided with the monitoring device 16, as shown in FIG. 11B, instead of omitting the content server main body 1a and the content storage unit 1b, the same configuration as in FIG. The content to be distributed may be stored in advance in the content storage unit 2b.

  Furthermore, as shown in FIG. 11C, the content distribution system to which the present invention is applicable may include the monitoring device 16 and the sub-distribution server 14 at the same time. Of course, as shown in FIG. 10 (d), in the content distribution system provided with the monitoring device 16 and the sub-distribution server 14 at the same time, the content server main body 1a and the content storage unit 1b are omitted and distributed to the content storage unit 2b. The content to be stored may be stored in advance.

(5-4. Configuration in which reception device and monitoring device are provided independently of distribution server)
Furthermore, in the content distribution system to which the present invention can be applied, as shown in FIG. 12 (a), it is possible to provide the receiving device 15 and the monitoring device 16 at the same time.

  Further, in the content distribution system provided with the reception device 15 and the monitoring device 16, as shown in FIG. 12B, instead of omitting the content server main body 1a and the content storage unit 1b, FIG. Similar to the above configuration, the content to be distributed may be stored in advance in the content storage unit 2b.

  Furthermore, as shown in FIG. 12C, the content distribution system to which the present invention is applicable may include the receiving device 15, the monitoring device 16, and the sub-distribution server 14 at the same time. Of course, as shown in FIG. 12 (d), in the content distribution system that includes the receiving device 15, the monitoring device 16, and the sub-distribution server 14, the content server body 1a and the content storage unit 1b are omitted, and content storage is performed. Content to be distributed to the unit 2b may be accumulated in advance.

(5-5. Other configuration examples)
Although not specifically illustrated, the distribution server determination unit 12 of the distribution server main body 2a is set to the distribution server determination in the same manner as the above-described configuration in which the sub distribution server 14, the reception device 15, or the monitoring device 16 is provided independently. It can also be provided on a network independently as a device.

  Of course, among the sub-distribution server 14, the reception device 15, and the monitoring device 16, a device that is provided independently on the network may be arbitrarily set, and the device may be provided on the network together with the distribution server determination device.

[6. Supplement)
The processing procedure of the distribution server 2 according to the present embodiment is such that a calculation unit such as a CPU executes a program stored in a storage unit such as a ROM (Read Only Memory) or a RAM, and an input unit such as a keyboard or an output such as a display. It can be realized by controlling the communication means such as the means or the interface circuit.

  Therefore, the computer having these means can realize various processes of the distribution server of this embodiment simply by reading the recording medium storing the program and executing the program. In addition, by recording the program on a removable recording medium, the various functions and various processes described above can be realized on an arbitrary computer.

  As the recording medium, a program medium such as a memory (not shown) such as a ROM may be used for processing by the microcomputer, and a program reading device is provided as an external storage device (not shown). It may be a program medium that can be read by inserting a recording medium there.

  In any case, the stored program is preferably configured to be accessed and executed by the microprocessor. Furthermore, it is preferable that the program is read out, and the read program is downloaded to the program storage area of the microcomputer and the program is executed. It is assumed that the download program is stored in the main device in advance.

  The program medium is a recording medium configured to be separable from the main body, such as a tape system such as a magnetic tape or a cassette tape, a magnetic disk such as a flexible disk or a hard disk, or a disk such as a CD / MO / MD / DVD. Fixed disk system, card system such as IC card (including memory card), or semiconductor memory such as mask ROM, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), flash ROM, etc. In particular, there are recording media that carry programs.

  In addition, if the system configuration is capable of connecting to a communication network including the Internet, the recording medium is preferably a recording medium that fluidly carries the program so as to download the program from the communication network.

  Further, when the program is downloaded from the communication network as described above, it is preferable that the download program is stored in the main device in advance or installed from another recording medium.

  As described above, the monitoring device 16 according to the present embodiment distributes the distribution load of the distribution server 2, and based on the access log from the user terminal 3 to the distribution server 2 to be monitored, When the local server load state monitoring unit 11 that predicts the distribution load and the local server load state monitoring unit 11 predicts that the distribution load to the distribution server 2 will be high, the content is distributed from a distribution server other than the distribution server 2 And a distribution server determination unit 12 for determining

  According to the above configuration, when the distribution load on the monitored distribution server 2 (own distribution server) is predicted to be increased by the own server load state monitoring unit 11, the distribution server determination unit 12 distributes the content from the other distribution server. It is decided that Therefore, since the content can be distributed from the other distribution server before the distribution load in the own distribution server becomes an overload state, the content can be stably distributed to the user terminal.

  In addition, since the own server load state monitoring unit 11 predicts the delivery load based on the access log for the own delivery server, the future delivery load can be appropriately predicted. Therefore, the distribution server determination unit 12 can appropriately determine whether or not to distribute the content from another distribution server, so that the content can be distributed to the user terminal more efficiently.

  Further, the own server load state monitoring unit 11 transmits a period Tsum in which a content distribution request that can permit distribution of content from the monitored distribution server is transmitted to the distribution server, the number k of channels used for content distribution, and It is preferable to predict the distribution load in the distribution server using the threshold value p1 set based on the time T1 for transferring the content to the user terminal.

  That is, the number of terminals that can simultaneously distribute content from a certain distribution server can be calculated from Tsum, k, and T1. Therefore, according to the above configuration, since the load on the distribution server is predicted by setting a threshold based on the above three parameters, it is possible to predict an appropriate distribution load. Therefore, the content can be distributed to the user terminal more efficiently.

  In addition, the distribution server 2 of the present embodiment includes the distribution load distribution device described in the above configuration. According to the above configuration, since the distribution server 2 includes the own server load state monitoring unit 11 and the distribution server determination unit 12, it is possible to efficiently distribute the content to the user terminal.

  Furthermore, the distribution server 2 includes an other server load state monitoring unit 13 that monitors a content distribution load in another distribution server.

  According to the above configuration, the content distribution load on the other distribution server is monitored by the other server load state monitoring unit 13. Therefore, when the distribution server determining unit 12 determines to distribute the content using another distribution server, it can be determined whether the distribution server distributes the content in consideration of the distribution load in the other distribution server. .

  That is, when the other server load state monitoring unit 13 determines that the distribution load is high in the other distribution server, the content is not distributed from the distribution server, and the content is distributed using another distribution server. Can be. Therefore, the content can be distributed to the user terminal more efficiently.

  Furthermore, it is preferable that the distribution server 2 distributes contents to each user terminal using a band allocated to each of the plurality of user terminals.

  According to the above configuration, since the band used for content distribution is individually assigned to each user terminal, the content can be distributed in a band fixed to each user terminal. Therefore, the content can be distributed to the user terminal in a more stable communication state.

  Furthermore, the content distribution system of the present embodiment includes a plurality of distribution servers including the distribution server 2 of the present embodiment, and a plurality of user terminals to which contents are distributed from any of the plurality of distribution servers. It is.

  In addition, the content distribution system according to the present embodiment includes a monitoring device 16 and a plurality of distribution servers 2 including at least one distribution server 2 whose distribution load is predicted by the own server load state monitoring unit 11 of the monitoring device 16. A plurality of user terminals 3 to which contents are distributed from any one of the plurality of distribution servers 2.

  According to the above configuration, since the distribution server 2 or the monitoring device 16 of the present embodiment is provided in the content distribution system, the content can be efficiently distributed to a plurality of user terminals.

  Furthermore, the content distribution system of the present embodiment preferably includes a sub-distribution server 14 that assists the content distribution by the distribution server 2.

  According to the above configuration, content distribution by the distribution server 2 is assisted by the sub-distribution server 14, so that the distribution load on the distribution server is reduced, and the content can be distributed more efficiently from the distribution server.

  Furthermore, the content distribution system of the present embodiment preferably includes a receiving device 15 that receives content distribution requests from a plurality of user terminals 3 in the content distribution system.

  According to the above configuration, the content distribution requests from the user terminals 3 can be centrally managed by the reception device 15, and the content distribution requests made to the plurality of distribution servers 2. Can be.

  Therefore, it is possible to prevent content distribution requests from being concentrated on a specific distribution server 2 and increase the load on the distribution server 2, and to distribute content to user terminals more efficiently.

  The present invention is not limited to the above-described embodiments, and embodiments modified within the scope of the claims are also included in the technical scope of the present invention.

  According to the present invention, since a large amount of content such as moving image data, music data, still image data, or application execution data can be efficiently distributed to the user terminal, the present invention is suitable for an information distribution service. ing.

It is a block diagram which shows the structure of the delivery server which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the content delivery system which concerns on one Embodiment of this invention. It is a figure which shows the structure of the content server, distribution server, and user terminal which are contained in the content distribution system of FIG. 4 is a time sequence showing exchange of information among the content server, distribution server, and user terminal of FIG. 3. It is a flowchart which shows the procedure of the process in the delivery server of FIG. Part (a) is a graph showing the relationship between the number of content distribution requests and the distribution start waiting time, and part (b) is a graph recording bandwidth control when stable content distribution is performed in the distribution server. Yes, part (c) is a graph recording bandwidth control when the distribution server is in an overload state. It is a figure which shows the relationship between the time regarding the delivery of content, and a bandwidth in one channel. It is a figure explaining the state in the case of performing band guarantee transmission between a delivery server and a user terminal. (A)-(c) is a figure which shows the modification of the content delivery system which concerns on one Embodiment of this invention. (A)-(d) is a figure which shows the other modification of the content delivery system which concerns on one Embodiment of this invention. (A)-(d) is a figure which shows the other modification of the content delivery system which concerns on one Embodiment of this invention. (A)-(d) is a figure which shows the other modification of the content delivery system which concerns on one Embodiment of this invention.

Explanation of symbols

2 distribution server 3 user terminal 11 own server load state monitoring unit (load state monitoring means)
12. Distribution server determination unit (distribution server determination means)
13 Other server load state monitoring unit (Other server load state monitoring means)
14 Sub-distribution server 15 Reception device 16 Monitoring device (distribution load distribution device)

Claims (12)

A distribution load distribution device that distributes a distribution load of a content distribution server,
Load state monitoring means for predicting a distribution load in the distribution server based on a log of access from the user terminal to the distribution server to be monitored;
A distribution server determining unit that determines that the content is distributed from a distribution server other than the distribution server when the load state monitoring unit predicts that the distribution load to the distribution server is high. Distribution load balancer.   The load state monitoring means further determines a period at which a content distribution request that can permit distribution of content from the monitoring target distribution server is transmitted to the distribution server, the number of channels used for content distribution, and the content as a user. The distribution load distribution apparatus according to claim 1, wherein a distribution load in the distribution server is predicted using a threshold value set based on a time for transferring to a terminal.   A distribution server comprising the distribution load distribution device according to claim 1.   4. The distribution server according to claim 3, further comprising other server load state monitoring means for monitoring a content distribution load in another distribution server.   The distribution server according to claim 3 or 4, wherein content distribution is performed to each user terminal using a band allocated to each of a plurality of user terminals.   The distribution load distribution device according to claim 1, a plurality of distribution servers including at least one distribution server whose distribution load is predicted by a load state monitoring unit of the distribution load distribution device, and a plurality of distribution servers A content distribution system comprising: a plurality of user terminals to which content is distributed from any one of them.   A plurality of distribution servers including the distribution server according to any one of claims 3 to 5, and a plurality of user terminals to which content is distributed from any of the plurality of distribution servers. Content distribution system.   8. The content distribution system according to claim 6, further comprising a sub-distribution server that assists the content distribution by the distribution server.   The content distribution system according to any one of claims 6 to 8, further comprising a receiving device that receives content distribution requests from a plurality of user terminals in the content distribution system. A distribution load distribution method for distributing a distribution load in a content distribution server,
A first step of predicting a distribution load in the distribution server based on a log of access to the distribution server to be monitored;
A second step of deciding to distribute content from a distribution server other than the distribution server when the first step is predicted to increase the distribution load on the distribution server. Load balancing method.   A distribution load distribution program for causing a computer to execute the distribution load distribution method according to claim 10.   A computer-readable recording medium on which the distribution load distribution program according to claim 11 is recorded.

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