KR20150010415A - Contents delivery network service method and broker apparatus for distributed caching - Google Patents

Abstract

The present invention relates a content delivery network service method and a relay apparatus for distributed caching, which is capable of supporting content to be distributed into a plurality of caches to logically increase a size of the cashes when at least one content provided from a content providing apparatus is stored in the cashes to be provided to a terminal. A content delivery network service method according to the present invention includes the steps of: calculating content identification information about a requested content by using a preset hash algorithm when a content request of a terminal is received; searching a content hash table managing hash keys of each content based on a hash key as the calculation result in order to confirm the requested content; selecting a cache to process the request content based on information about a mapping between the content hash table and the caches; and processing the requested content by the selected cache, so that the distributed processing of caches can be promoted.

Description

[0001] The present invention relates to a content delivery service method and a relay apparatus for distributed caching,

The present invention relates to a content transfer service, and more particularly, to a content transfer service, in which one or more contents provided by a content providing apparatus are stored in a plurality of cache apparatuses and provided to a terminal apparatus through a plurality of cache apparatuses, And more particularly, to a content transmission service method and a relay apparatus for distributed caching capable of logically increasing the size of a cache by enabling distributed storage in a device.

2. Description of the Related Art [0002] Recently, as a performance of a user terminal device such as a smart phone has been improved and a mobile communication technology has developed, a user accesses a content providing device of a content provider (CP) , Audio, applications, and so on.

However, the number of content providing apparatuses that can be constructed by the content provider is limited due to various reasons such as cost. On the other hand, since the number of users is rapidly increasing, the load of the content providing apparatus is rapidly increased, Problems such as interruption occur.

A CDN (Contents Delivery Network) service is an emerging technology to solve this problem. The CDN service is a service for reliably delivering various contents including moving pictures such as movies and music videos to a user. The CDN service typically stores contents in a plurality of cache devices distributed on a network in advance, ) Server and selects the optimum cache device from among the plurality of cache devices and transmits the requested content to the user terminal through the selected cache device. As a result, the content transmission speed is improved through the CDN service, and more stable content transmission becomes possible.

Meanwhile, in recent years, various types of contents provided through the Internet have been diversified, and each of these contents has different service patterns according to service purpose.

For example, in the case of the online shopping mall service, a plurality of small-sized contents are transmitted to the user's terminal device at a time according to the contents request of the terminal device. In the case of the online game service, a large-capacity file is transmitted at a time at the time of transmitting the content, and the content request tends to be concentrated from a plurality of users at a particular time. Also, in the case of UCC (User Created Contents) service or SNS (Social Network Service), it has a long-tailed user access frequency.

However, since there is a limit in increasing the storage capacity of individual cache devices in the content transfer service, the number of contents that can be stored in the cache device is also limited. Therefore, in the past, contents are selectively sorted according to a request frequency or a request of a content provider, and the content is stored in a cache device. As a result, contents having a long-term user access frequency provided by UCC, SNS, .

Published Korean Patent Application No. 2009-0130615, December 24, 2009 (Name: Method and system for transmitting content using a grid farm)

The present invention provides one or more contents provided by a content providing apparatus in a plurality of cache apparatuses and provides the same to a terminal apparatus through a plurality of cache apparatuses, A content transmission service method and a relay apparatus for distributed caching which can obtain an increase effect of a content delivery service.

Particularly, the present invention increases the cache size logically through distributed caching of a plurality of cache devices, without physically increasing the size of the cache, so that content with a long tailed user access frequency can also be serviced through the cache device. A content transmission service method and a relay apparatus.

The present invention provides, as means for solving the above problems, a communication interface unit for communicating with at least one of a terminal device and a plurality of cache devices; A storage unit for storing a content hash table for managing a content-based hash key and mapping information mapping the plurality of cache devices; And a content hash table that manages a content-based hash key by using a result of the operation as a hash key, searches the content hash table for requesting content, And a relay controller for checking contents to be requested, selecting a cache apparatus to process the requested contents based on the mapping information, and controlling the selected cache apparatus to process the contents request .

In addition, according to another aspect of the present invention, there is provided a relay apparatus comprising: a receiving unit for receiving a content request message of a terminal apparatus; Calculating content identification information of the requested content included in the content request message using a preset hash algorithm; Searching the content hash table for managing the content-based hash key by using the operation result value as a hash key, and confirming the requested content; A first selection step of selecting, from among the plurality of cache devices, a cache device to process the requested content based on mapping information between the content hash table and a plurality of cache devices; And controlling the selected cache device to process the requested content. The content delivery service method for distributed caching includes:

According to a content transmission service method and a relay apparatus for distributed caching of the present invention, a content providing apparatus distributes a plurality of contents to be distributed to a terminal apparatus to a plurality of cache apparatuses arranged in a communication network, By distributing requests for a plurality of contents, the cache size can be logically increased, and the possibility of receiving a content transfer service for a content having a long service pattern can be increased by increasing the cache size .

Particularly, the present invention has an excellent effect of improving the quality of service of a content transmission service without adding a large cost by efficiently using cache devices located in different places.

In addition, the present invention efficiently manages and manages content and cache devices based on key values generated by using a hash algorithm, efficiently manages content movement among a plurality of cache devices due to expansion or reduction of cache devices in distributed caching can do.

1 is a block diagram schematically showing the entire structure of a content transmission system according to the present invention.
2 is a block diagram illustrating an example of a connection structure between a cache apparatus and a relay apparatus in a content transmission system according to the present invention.
3 is a block diagram illustrating another example of a connection structure between a cache apparatus and a relay apparatus in the content transmission system according to the present invention.
4 is a block diagram showing a configuration of a relay apparatus in a content transmission system according to the present invention.
5 is a block diagram showing a configuration of a cache apparatus in a content transmission system according to the present invention.
6 is a block diagram showing a configuration of a central management apparatus in a content transmission system according to the present invention.
7 is a flowchart illustrating an operation of a relay apparatus in a content transmission service method for distributed caching according to the present invention.
8 is a flowchart illustrating an operation of a cache apparatus in a content transmission service method for distributed caching according to the present invention.
9 is a flowchart illustrating an operation of a central management apparatus in a content transmission service method for distributed caching according to the present invention.
FIG. 10 and FIG. 11 are schematic diagrams illustrating a process of changing a content storage range between cache devices according to the logarithmic variation of cache devices in the content transfer service for distributed caching according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and the accompanying drawings, detailed description of well-known functions or constructions that may obscure the subject matter of the present invention will be omitted. It should be noted that the same constituent elements are denoted by the same reference numerals as possible throughout the drawings.

FIG. 1 is a block diagram schematically showing the overall structure of a system in which a content transmission service according to the present invention is performed.

The contents transfer service according to the present invention is for transferring various kinds of contents provided by the contents providing apparatus 200 to the terminal apparatus 100 through the communication network 10.

Here, the terminal apparatus 100 is a user side apparatus that requests a photograph, a web document, a moving image, and contents through the communication network 10 and receives the requested contents. The terminal device 100 may be any user device having a communication function for connecting to the communication network 10 and transmitting and receiving data. For example, the terminal device 100 may be a mobile phone, a smart phone, a tablet PC, a personal computer Digital assistants and notebook PCs as well as fixed devices such as desktop PCs, Internet TVs (smart TVs).

The content providing apparatus 200 is a server apparatus for a content provider (CP) to serve a plurality of contents. The content providing apparatus 200 may include one or more servers, and in particular, includes an origin server in which a plurality of contents to be provided to a user by a content provider is stored.

In addition, the communication network 10 is a communication medium in which terminal devices 100 on the user side and content providing apparatuses 200 on the content provider side can freely connect and transmit / receive data, Any kind of communication network can be applied. For example, the communication network 10 may include a mobile communication network classified according to a communication method, a wireless network including a local communication network such as Wi-Fi or Bluetooth, and a wired network such as the Internet, or an integrated network thereof.

The content delivery system for providing the content provided by the content providing apparatus 200 to the terminal apparatus 100 in a stable and prompt manner includes at least one relay apparatus 300, a plurality of cache apparatuses 400, Device 500 as shown in FIG. Of course, the content transmission system may further include a DNS (Domain Name System) server for mapping the URL address to IP and delivering it, or a GLB (Global Load Balancing) server for performing load balancing in addition to the above configuration, Since there is no direct connection with the distributed caching function according to the invention, its illustration and description will be omitted.

The at least one relay device 300 is a means for controlling the content transfer service to be distributed among the plurality of cache devices 400. [ More specifically, the at least one relay device 300 has information on a content storage range set for each of the plurality of cache devices 400. The content hash table managing the hash key of each content calculated using the predetermined hash algorithm and the mapping information mapping each of the plurality of cache devices 400 may be managed. In addition, when at least one of the relay apparatuses 300 is located between the terminal apparatus 100 and the plurality of cache apparatuses 400 and receives a content request, And transmits the content request to the selected cache apparatus 400. The cache apparatus 400 transmits the content request to the cache apparatus 400. [ In particular, when the relay apparatus 300 selects the cache apparatus 400 to process the content request, the relay apparatus 300 calculates a hash key for identifying the content based on the content identification information of the requested content. The relay apparatus 300 can compare the content hash table based on the calculated hash key to identify the requested content and the cache apparatus 400 mapped thereto. Particularly, in the present invention, in order to efficiently transmit contents, content having a popularity, that is, a content whose user's access frequency is equal to or higher than a reference value is redundantly stored in a plurality of cache devices 400, . At this time, the cache apparatus 400 may be selected on the side with a smaller load, or may be selected in accordance with the round robin method or the like.

For reference, the content request can be delivered through an HTTP REQUEST message. Also, the one or more relay apparatuses 300 may receive the content request of the terminal apparatus 100 according to the intervention of the DNS server or the GLB server. For example, the terminal device 100 transmits a URL indicating content desired by the user to the DNS server or the GLB server, queries the IP address, and receives the IP address of the relay device 300 from the DNS server or the GLB server And transmit the content request to the relay apparatus 300 corresponding to the received IP address.

The plurality of cache devices 400 store content corresponding to each content storage range among the contents to be provided to the terminal device 100 from the content providing device 200. [ Here, the method of storing contents in the cache apparatus 400 may be performed by previously transmitting the contents from the contents providing apparatus 200 to the cache apparatus 400 and storing the contents in the cache apparatus 400 before the service is executed, The content transmitted from the providing apparatus 200 to the terminal apparatus 100 is copied and stored.

Upon receiving the content request of the terminal device 100 in response to the intervention of the relay device 300, it is determined whether or not the requested content is stored therein, and if the stored content is stored, (100).

These cache devices 400 are distributed on the communication network 10, for example, in the case of a mobile communication network, they may be disposed at a connection point of a radio access network (RAN). More specifically, it may be connected through a switching device to a point where the radio access network (RAN) is connected.

In addition, the one or more relay apparatuses 300 and the plurality of cache apparatuses 400 may be interworked in various ways such as a redirect method and a proxy method.

2 and 3 are views illustrating an interworking structure between one or more relay apparatuses 300 and a plurality of cache apparatuses 400 in a content transmission system according to the present invention.

2 is a block diagram illustrating an interworking structure of a relay device and a cache device in a content transmission system using a redirect technique. In this embodiment, one relay device 300a and a plurality of cache devices 400a to 400c are interlocked. The one relay device 300a is not directly connected to the plurality of cache devices 400a to 400 and can operate independently.

In this embodiment, the relay apparatus 300a has information on the content storage range of each of the plurality of cache apparatuses 400a to 400c. The content storage range may be set based on a key value calculated through hash calculation from content identification information (e.g., URL information). Specifically, a content hash table for managing a content-based hash key and mapping information mapping the plurality of cache devices may be set.

The relay device 300a receives a content request from the terminal device 100 and compares it with a predetermined content storage range of each of the plurality of cache devices 400a to 400c, . The relay apparatus 300a transmits a redirection message (for example, HTTP REDIRECT MESSAGE) including the IP address of the selected cache apparatus (for example, 400a) to the terminal apparatus 100. [ The terminal device 100 transmits the content request message again to the selected cache device 400a among the plurality of cache devices 400a to 400c.

The cache apparatus 400a receiving the content request message transmits the stored content to the terminal device 100. [ In particular, when the transparent caching scheme is applied, the cache apparatus 400a checks whether the requested content is stored, transmits the stored content to the terminal device 100, and if not, After the content request message is transmitted to the content providing apparatus 200, the content transmitted from the content providing apparatus 300 to the terminal apparatus 100 is copied and stored. Accordingly, the content request is distributed and transmitted by the relay device 300a, thereby implementing distributed caching of content to the cache devices 400a to 400c and distribution processing of the content request.

3 is a block diagram illustrating an interworking structure of a cache apparatus and a relay apparatus to which a proxy scheme is applied in a content transmission system according to another embodiment of the present invention. A plurality of relay apparatuses 300a to 300c and a plurality of cache apparatuses 400a to 400c are provided in the present embodiment. The plurality of relay apparatuses 300a to 300c include a plurality of relay apparatuses 300a to 300c and a plurality of cache apparatuses 400a to 400c, And 400c and is connected to all of the plurality of cache devices 400a to 400c and operates as a proxy server. Here, the relay apparatuses 300a to 300c may be configured to correspond to bandwidths required for the terminal apparatuses 100. [ In addition, since the network interval between the relay apparatuses 300a to 300c and the cache apparatuses 400a to 400c may be very congested, it may be implemented using a separate internal network. In addition, the plurality of relay devices 300a to 300c and the plurality of cache devices 400a to 400c may be mapped 1: 1. In another embodiment of the present invention, the relay apparatuses 300a to 300c and the cache apparatuses 400a to 400c mapped to 1: 1 may be implemented as one server apparatus and connected to each other through a loopback interface. On the other hand, the relay apparatuses 300a to 300c may be connected to other unmapped cache apparatuses 400a to 400c through a network.

3, the plurality of relay apparatuses 300a to 300c includes information on the content storage ranges of the plurality of cache apparatuses 400a to 400c, respectively, as in the embodiment of FIG. The content storage range may be set based on a key value calculated through hash calculation from content identification information (e.g., URL information). Specifically, a content hash table for managing a content-based hash key and mapping information mapping the plurality of cache devices may be set.

One of the plurality of relay apparatuses 300a to 300c receives the content request transmitted from the terminal apparatus 100. [ Specifically, the terminal device 100 transmits the URL corresponding to the content desired to be received by the DNS server or the GLB server to inquire the IP address, and in response to the inquiry, the relay device 300a to 300c And receives the IP address of the device (for example, 300a). Accordingly, the terminal device 100 transmits a content request message to the relay device 300a corresponding to the IP address. Here, the operation of the DNS server or the GLB server is well known in the conventional CDN technology field, and is not directly related to the distributed caching according to the present invention, so a detailed description will be omitted.

The relay device 300a receiving the content request message of the terminal device 100 compares the content storage ranges of the plurality of cache devices 400a to 400c with the predetermined content storage ranges, . Then, the relay apparatus 300a transmits the contents request message of the terminal apparatus 100 to the selected cache apparatus (for example, 400a). The content request message is delivered through a loopback interface when the relay apparatus 300a and the cache apparatus 400a are implemented as a single server and may be delivered through a network if the relay apparatus 300a and the cache apparatus 400a are implemented as different servers .

The cache apparatus 400a receiving the content request message through the relay apparatus 300a transmits the stored content to the terminal apparatus 100. [ At this time, the content may be transmitted to the terminal device 100 through the relay device 300a. In addition, when the transparent caching scheme is applied, the cache apparatus 400a checks whether the requested content is stored, transmits the stored content to the terminal device 100, and if not, After the content request message is transmitted to the content providing apparatus 200, the content transmitted from the content providing apparatus 300 to the terminal apparatus 100 is copied and stored.

Meanwhile, when the relay apparatus 300 and the cache apparatus 400 are interlocked with each other as in the above-described FIG. 2 and FIG. 3, logarithmic variation may occur in the cache apparatus 400 due to an increase in the number of users or a server failure. When the logarithmic variation of the cache apparatus occurs as described above, the content storage range set in the plurality of cache apparatuses 400 must be adjusted. The central management apparatus 500 shown in FIG. 1 is a configuration for efficiently adjusting the content storage range between the cache apparatuses 400 according to the variation of the cache apparatus.

1, the central management unit 500 monitors a plurality of cache devices 400 in the content transmission system according to the present invention, and when a logarithmic change occurs, It is a means for adjusting the content storage range. Specifically, the central management apparatus 500 stores mapping information on a plurality of cache devices 400 and content storage ranges, and history information on changes in content storage ranges of a plurality of cache devices 400. The central management unit 500 monitors the statuses of the plurality of cache devices 400 and confirms whether the number of cache devices 400 has changed. As a result, when a new cache apparatus is added, the central management apparatus 500 divides the content storage range of currently operating cache apparatuses 400 into the new cache apparatus. In detail, the central management apparatus 500 calculates a distribution unit to be distributed from the plurality of cache apparatuses 400 to the new cache apparatus in consideration of the number of currently operating cache apparatuses 400, the storage capacity of the new cache apparatus, . Then, the central management apparatus 500 extracts each of the calculated distributed units from among the content storage ranges of the plurality of cache apparatuses 400, and sets the extracted distributed units in a new cache apparatus. At this time, it is possible to extract as many distributed units from the end of the content storage range of each cache apparatus 400. The central management apparatus 500 changes mapping information on the content storage range with the plurality of cache devices 400 by reflecting changes in the content storage range and transmits the changed mapping information to one or more relay apparatuses 300 So that the relay apparatus 300 operates based on the changed mapping information.

On the other hand, when a reduction occurs among a plurality of cache apparatuses 400, the central management apparatus 500 considers the content storage range set in the cache apparatus to be reduced to be equal to the number of remaining cache apparatuses 400, . Then, the content storage range of the remaining cache devices 400 is changed by allocating the uniformly divided content storage range to at least one of the remaining cache devices 400. [ In the same way as described above, the central management apparatus 500 changes mapping information of the content storage range with a plurality of cache devices 400 by reflecting the change, and transmits the changed mapping information to one or more relay apparatuses 300 So that the relay apparatus 300 can operate based on the changed mapping information.

Next, detailed configurations and operations of the relay device 300, the cache device 400, and the central management device 500 included in the content transmission system according to the present invention will be individually examined.

4 is a block diagram showing a configuration of a relay apparatus 300 in a content transmission system according to the present invention.

Referring to FIG. 4, the relay apparatus 300 according to the present invention may include a communication interface unit 310, a storage unit 320, and a relay control unit 330.

The communication interface unit 310 is a means for transmitting and receiving data with at least one of the terminal apparatus 100 and the plurality of cache apparatuses 400. Specifically, the communication interface unit 310 connects to the communication network 10, receives a content request message from the terminal device 100, transmits a redirect request to the terminal device 100, The content request message can be delivered to one of the cache devices 400 via the network or the loopback interface.

The storage unit 320 stores data and programs necessary for operation of the relay device 300 and basically stores the operating program of the relay device 300 and the program implemented to process the process of FIG. have. In particular, the storage unit 320 stores a plurality of cache devices 400 and mapping information mapping the respective content storage ranges. This can be stored as a mapping between the content hash table managing the hash key value for each content calculated according to the preset hash algorithm (see Equation 1) and the multiple cache devices 400.

Lastly, the relay control unit 330 is a means for controlling the overall operation of the relay apparatus 300 according to the present invention, in particular, can control the service distribution processing for the multiple cache apparatuses 400. [

Specifically, the relay control unit 330, when receiving the content request of the terminal device 100 through the communication interface unit 310, compares the cache information stored in the storage unit 320 with the mapping information of the content storage range Selects a cache apparatus 400 to process a corresponding content request among a plurality of cache apparatuses 400 and controls the selected cache apparatus 400 to transmit a content request of the terminal apparatus 100. [ Specifically, the relay control unit 330 transmits a redirection request to the IP address of the selected cache apparatus 400 to the terminal apparatus 100, or transmits a content request of the terminal apparatus 100 to the selected cache apparatus 400 You can send it directly.

In addition, when a request for some popular content is to be processed in a plurality of cache apparatuses 400, the relay control unit 330 confirms the popularity of the requested content. If the popularity is equal to or higher than the reference level, the relay control unit 330 selects a plurality of cache apparatuses 400 in accordance with a predetermined order. More specifically, when content having a popularity level equal to or higher than a reference level is requested, the relay control unit 330 sequentially selects one of the plurality of cache devices 400 in accordance with the round robin method without considering information on the predetermined content storage range . Accordingly, a plurality of cache apparatuses 400 can alternately process requests for the popular content.

In addition, the relay control unit 330 may use the hash algorithm in selecting the cache apparatus 400 in comparison with the predetermined content storage range.

Specifically, the relay control unit 330 calculates a hash key value (Range) corresponding to the requested content by applying the content identification information (e.g., URL) of the requested content to Equation (1).

Here, Range_Count is a unit for minimizing duplication of contents, and can be arbitrarily set. Accordingly, the relay control unit 330 performs hash operation on the content identification information of the requested content with a predetermined hash function, modulo the operation result with the first reference value (Range_Count), and calculates the moduler operation result value as a hash key value .

The relay control unit 330 can search the content hash table managing the hash key value for each content using the calculated hash key value, check the requested content, and measure or check the popularity of the requested content. In addition, the cache device 400 mapped to the requested content can be checked and selected.

The operation of the relay control unit 330 described above may be more easily understood by referring to the description of FIG. 7 to be described later.

Next, Fig. 5 is a block diagram showing the configuration of the cache apparatus 400 in the content transmission system according to the present invention.

5, the cache apparatus 400 may include a communication interface unit 410, a storage unit 420, and a cache control unit 430.

The communication interface unit 410 of the cache apparatus 400 is a means for transmitting and receiving data with at least one of the terminal apparatus 100, the relay apparatus 300 and the content providing apparatus 200. The communication interface unit 410 may be configured to communicate with any one of the terminal device 100, the relay device 300, and the content providing device 200 through the communication network 10 and / . In particular, when the cache apparatus 400 is implemented as a specific relay apparatus 300 and a single server, the communication interface unit 410 may be implemented to communicate with the relay apparatus 300 through a loopback interface have.

The storage unit 420 is a means for storing data and programs necessary for the operation of the cache apparatus 400, and in particular, stores a part or all of one or more contents.

The cache control unit 430 controls the entire operation of the cache apparatus 400 to store the content in the storage unit 420 or to control the transmission of the requested content to the terminal device 100.

In particular, the operation of the cache controller 430 may vary according to the caching scheme. Particularly, in the case of the transparent caching scheme, when the content request of the terminal device 100 is received according to the intervention of the relay device 300, it is determined whether or not the requested content is stored therein, , And transmits the stored contents to the terminal device (100). In contrast, if the content is not stored, the content request may be transmitted to the content providing apparatus 200, and the content transmitted from the content providing apparatus 200 may be copied in the storage unit 420 in response to the content request. The operation of the cache control unit 430 described above can be more easily understood with reference to the description of FIG. 8 to be described later.

Next, Fig. 6 is a block diagram showing the configuration of the central management apparatus 500 in the content transmission system according to the present invention.

6, the central management apparatus 500 may include a communication interface unit 510, a storage unit 520, and a distribution management unit 530. [

The communication interface unit 510 of the central management apparatus 500 is a means for communicating with at least one of the relay apparatus 300 and the cache apparatus 400. The communication interface unit 510 is connected to the communication network 10, . ≪ / RTI >

The storage unit 520 is a means for storing data necessary for the operation of the central management apparatus 500 and a program executed by the distribution management unit 530. In particular, Mapping information, and history information on changes in the content storage range of a plurality of cache devices 400. [

The distributed management unit 530 performs a function of managing content distributed caching according to the variation of the cache apparatus 400 according to the present invention in cooperation with the communication interface unit 510 and the storage unit 520. [

Specifically, the distribution management unit 530 monitors a plurality of cache devices 400 to check if logarithmic variation occurs. As a result, when a new cache device is added, the distribution manager 530 receives a new cache from the plurality of cache devices 400 in consideration of the number of currently operating cache devices 400 and the storage capacity of the new cache device, Calculates the distributed unit to be distributed to the apparatus, extracts each of the calculated distributed units in the content storage range of the plurality of cache apparatuses 400, and sets the extracted distributed units in the new cache apparatus. At this time, it is possible to extract only the distribution unit from the end portion (for example, a storage location, a hash key value, etc.) of the content storage range of each cache apparatus 400. On the contrary, when the reduction of the plurality of cache devices 400 occurs, the distributed management unit 530 performs the equalization division in consideration of the number of the remaining cache devices 400 and the storage capacity, do. Then, the content storage range of the remaining cache devices 400 is changed by allocating the uniformly divided content storage range to at least one of the remaining cache devices 400. [

The distribution management unit 530 changes the mapping information stored in the storage unit 520 by reflecting the changes of the content storage range according to the above and transmits the changed mapping information to the one or more relay apparatuses 300, Thereby allowing the device 300 to operate based on the changed mapping information.

In addition, the distribution manager 530 may control the content movement between the cache devices 400, depending on the changed mapping information, as the case may be.

Next, a content transmission service method for distributed caching of the content transmission system configured as described above will be described with reference to FIGS. 7 to 9. FIG.

7 is a flowchart illustrating a content transmission service method for distributed caching implemented by the relay apparatus 300 in the content transmission system according to the present invention. In the embodiment of FIG. 7, it is assumed that popular contents are stored in a plurality of cache devices 400 at the same time, and the remaining contents are stored in a plurality of cache devices 400 in a distributed manner.

Referring to FIG. 7, the relay apparatus 300 sets and stores a content storage range for each of the plurality of cache apparatuses 400 (S105). For this, the relay apparatus 300 may receive the mapping information of the content storage range from the cache apparatus and the preset cache apparatus from the central management apparatus 500. The content storage range can be set by dividing a URL value defining the content identification information, specifically, the location of the content on the network into a predetermined range. In particular, the present invention can be set using a hash key value obtained by calculating content identification information (e.g., URL) using a predetermined hash algorithm so that efficient management and quick comparison are possible. That is, the content storage range is defined as a content hash table that manages a hash key value calculated using a predetermined hash algorithm for each content, and the content hash table can be mapped with a plurality of cache devices.

The computation of the key value can be understood in more detail through steps S115 to S120.

Then, the relay apparatus 300 confirms whether a content request is received from the terminal device 100 (S110).

Upon receipt of the content request from the terminal device 100, the relay device 300 compares the previously stored content with the previously stored content and maps the requested content to the cache devices 400, The cache device 400 to which the content request is to be transmitted is selected. This can be done through steps S115 to S140.

More specifically, the relay apparatus 300 calculates content identification information of the content requested by the terminal device 100 through a predetermined hash function (S115).

Then, the hash-computed function is modulo-computed with a predetermined first reference value (Range_Count) (S120).

In step S125, the content hash table managing the hash key value for each content is searched for the modulo operation result of step S120 described above as the hash key value, and the requested content is confirmed. Here, the relay apparatus 300 of the present invention can further confirm the popularity of the requested content. To this end, the relay apparatus 300 of the present invention searches for the content hash table, and the confirmed content is the most recently requested content, so that the popularity is recorded at the top of the Least Requested Used (LRU) table.

Then, the relay apparatus 300 confirms whether the popularity of the requested content is equal to or higher than a specified level (S130). More specifically, the relay apparatus 300 checks the popularity LRU table to confirm whether the requested content has a popularity higher than a reference level.

If it is determined that the requested content has a popularity higher than the reference level, the relay device 300 selects one of the plurality of cache devices 400 in a predetermined order (S135). For example, the relay apparatus 300 can select the cache apparatus 400 according to the round robin scheme. This is a selection for distributing the load evenly by allocating the requested content to the plurality of cache devices 400 when the requested frequency of the requested content is high.

On the contrary, when the requested content does not have a popularity higher than the reference level, the relay apparatus 300 refers to the mapping information between the content storage range and the cache apparatus, A cache apparatus having a content storage range is selected (S140).

When the cache device is selected, the relay device 300 processes the content request of the terminal device 100 to be transmitted to the selected cache device 400 (S145). The transmission to the selected cache apparatus 400 may be performed by requesting redirection together with the IP address of the cache apparatus 400 selected by the terminal apparatus 100 according to the redirect method or the relay apparatus 300 may operate as a proxy server And transmit the content request directly to the selected cache device 400. [

Through the operation of the relay device 300, a content request can be appropriately distributed to a plurality of cache devices 400. [ Upon receiving the content request message, the plurality of cache devices 400 extract the requested content and transmit the extracted content to the terminal device 100.

In this case, in the case of the transparent caching method, content caching is performed in real time during service execution. To this end, the cache apparatus 400 should further check whether content is stored.

8 is a flowchart illustrating a content transmission service method for distributed caching performed by the cache apparatus 400 to which the transparent caching scheme is applied.

Referring to FIG. 8, the cache apparatus 400 may receive a content request of the terminal device 100 through the intervention of the relay apparatus 300 as described above (S205).

Upon receiving the content request, the cache apparatus 400 first confirms whether the requested content is stored (S210). Here, the method of confirming whether or not to store the content may include a method of comparing the URL of the stored content with the URL of the requested content, a method of receiving a part of the requested content (e.g., Prefix data) Method, or a combination thereof may be used.

As a result, if the requested content is stored, the cache device 400 transmits the stored content to the terminal device 100 (S230), as described above.

On the other hand, if the requested content is not stored, the cache apparatus 400 transmits the received content request to the content providing apparatus 400 as a source server (S215).

When the content requested by the content providing apparatus 400 is transmitted to the terminal apparatus 100, the cache apparatus 400 copies and stores the content transmitted from the content providing apparatus 400, (Step S225). The stored contents can be used to be provided to the corresponding terminal device in the next content request.

Finally, FIG. 9 is a flowchart illustrating a content transmission service method for distributed caching in the central management apparatus according to the present invention.

Referring to FIG. 9, the central management apparatus 500 includes mapping information on a plurality of cache devices 400 and content storage ranges, and a history of changes in content storage ranges of a plurality of cache devices 400 Information is stored (S305).

In the content transmission system according to the present invention, the central management unit 500 monitors a plurality of cache devices 400 and determines whether a change occurs in the number of cache devices 400 (S310).

As a result, when a new cache apparatus is added (S315), the central management apparatus 500 divides the content storage range of the currently operating cache apparatuses 400 and distributes the content storage range to the new cache apparatus, 400, and the storage capacity of the new cache apparatus, the distributed unit to be distributed from the plurality of cache apparatuses 400 to the new cache apparatus is calculated (S320).

 In step S325, the central management apparatus 500 extracts the calculated distribution unit from the content storage range of the plurality of cache apparatuses 400 as a content distribution range. In particular, the central management unit 500 extracts contents of a distributed unit from the end of the content storage range of the multiple cache devices 400 as a content distribution range.

The central management apparatus 500 allocates each content distribution range extracted from the content storage range of the plurality of cache apparatuses 400 to the newly added cache apparatus and sets the content distribution range (S330).

On the contrary, when a reduction occurs among a plurality of cache devices 400, the content storage range set in the cache device 400 to be reduced is divided according to the number of remaining cache devices 400 and the storage capacity, (S335).

Then, the uniform distribution of content distribution is further allocated to one or more of the remaining cache devices 400 (S340).

When the content storage range of the cache devices 400 is changed, the central management unit 500 reflects the change of the content storage range and stores the mapping information for the content storage range with the plurality of cache devices 400 (S345).

Then, the changed mapping information is transmitted to the one or more relay apparatuses 300 so that the relay apparatus 300 operates based on the changed mapping information (S350). In the case of the transparent caching scheme, the relay apparatus 300 distributes the content request to the plurality of cache apparatuses 400 based on the changed mapping information, and thereby, the plurality of cache apparatuses 400 receive the content corresponding to the changed mapping information Is stored through the processing as shown in Fig.

On the contrary, when the method is not the transparency caching method, the central management unit 500 may further perform a function of distributing contents to the plurality of cache devices 400 according to the changed mapping information. That is, the central management apparatus 500 controls the plurality of cache devices 400 to transmit, delete, or receive contents corresponding to the content distribution range to or from another cache device in accordance with the changed mapping information can do. The content transfer between the plurality of cache devices 400 may be performed through direct communication between the cache devices 400 or may be performed through the relay device 300, There is also.

FIG. 10 and FIG. 11 are schematic diagrams illustrating a process of changing a content storage range between cache devices according to the logarithmic variation of cache devices in the content transfer service for distributed caching according to the present invention.

FIG. 10 is a diagram illustrating a distribution process of contents according to the extension of the cache apparatus 400, wherein contents 1 to 9 and A to I are stored in one cache apparatus S1, When the cache apparatus S2 is further expanded, nine contents A to I corresponding to 1/2 of the contents storage range are distributed to the new cache apparatus S2.

If the cache device S3 is added again, all 18 contents must be distributed to three cache devices. Therefore, six contents can be stored for each cache device. Therefore, three contents 7 to 9 and G to I are respectively extracted from the cache apparatuses S1 and S2 and distributed to the new cache apparatus S3.

In addition, when the cache device S4 is again installed, all 18 contents are distributed to four cache devices. Therefore, one content 6 and F are extracted from the cache devices S1 and S2, , And distributes the extracted contents H and I to the new cache apparatus S4.

Therefore, when the cache apparatus is added, the original cache apparatus can distribute contents while maintaining the maximum content storage range set for itself.

Meanwhile, FIG. 11 is a diagram illustrating a content distribution process when the cache apparatus 400 is reduced, and shows a case where the cache apparatuses 400 are decremented step by step in six cache apparatuses.

11, when six cache devices S1 to S6 store three contents, respectively, when the cache device S1 is removed due to a failure or the like, The contents 1, 2, and 3 are distributed to the cache devices S2, S3, and S4, respectively.

When the cache device S6 is removed again, the contents 4, D, and G stored in the cache device S6 are distributed to the cache devices S2, S3, and S5, respectively.

When the cache device S3 is removed again, the contents 7 to 9, 2, and G stored in the cache device S3 are distributed to the cache devices S2, S4, and S5.

Likewise, in the case where the cache apparatus S3 is reduced through the above-described process, the content storage range of the remaining cache apparatus S3 remains unchanged, and content distribution can be properly performed.

The content transmission service method according to the present invention can be implemented in a form of software readable by various computer means and recorded in a computer-readable recording medium. Here, the recording medium may include program commands, data files, data structures, and the like, alone or in combination. Program instructions to be recorded on a recording medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software. For example, the recording medium may be an optical recording medium such as a magnetic medium such as a hard disk, a floppy disk and a magnetic tape, a compact disk read only memory (CD-ROM), a digital video disk (DVD) Includes a hardware device that is specially configured to store and execute program instructions such as a magneto-optical medium such as a floppy disk and a ROM, a random access memory (RAM), a flash memory, do. Examples of program instructions may include machine language code such as those generated by a compiler, as well as high-level language code that may be executed by a computer using an interpreter or the like. Such a hardware device may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

In addition, computer programs (also known as programs, software, software applications, scripts, or code) that are embedded in an apparatus in accordance with the present invention and that perform the methods of the present invention include compiled or interpreted languages, a priori or procedural languages , And may be deployed in any form including standalone programs or modules, components, subroutines, or other units suitable for use in a computer environment. A computer program does not necessarily correspond to a file in the file system. The program may be stored in a single file provided to the requested program, or in multiple interactive files (e.g., a file storing one or more modules, subprograms, or portions of code) (E.g., one or more scripts stored in a markup language document). A computer program may be deployed to run on multiple computers or on one computer, located on one site or distributed across multiple sites and interconnected by a communications network.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be apparent to those skilled in the art. Furthermore, although specific terms are used in this specification and the drawings, they are used in a generic sense only to facilitate the description of the invention and to facilitate understanding of the invention, and are not intended to limit the scope of the invention.

Therefore, the scope of the present invention should not be limited by the described embodiments but should be defined by the claims.

According to a content transmission service method and a relay apparatus for distributed caching of the present invention, a plurality of contents to be provided from a content providing apparatus to a terminal apparatus are distributed cached to a plurality of cache apparatuses arranged in a communication network through a relay apparatus, It is possible to logically increase the cache size by distributing the requests for the plurality of contents in the cache apparatus of the server 200. The CDN service is also supported for the contents having the long service pattern through the increase of the cache size .

In particular, the present invention has an excellent effect of improving the quality of service of a CDN without adding a large cost by efficiently using cache devices located at different locations.

In addition, the present invention efficiently manages and manages content and cache devices based on key values generated by using a hash algorithm, efficiently manages content movement among a plurality of cache devices due to expansion or reduction of cache devices in distributed caching can do.

10: Network
100: terminal device
200: Content providing device
300: Relay device
400: cache device
500: central management unit

Claims (11)

A communication interface for communicating with at least one of a terminal device and a plurality of cache devices;
A storage unit for storing a content hash table for managing a content-based hash key and mapping information mapping the plurality of cache devices;
Upon receiving the content request of the terminal, the content identification information of the requested content is calculated using a predetermined hash algorithm, the content hash table managing the hash key for each content by using the calculation result as a hash key, And selecting a cache apparatus to process the requested content on the basis of the mapping information and controlling the selected cache apparatus to process the content request. The apparatus of claim 1, wherein the relay control unit
And sequentially selects one cache device of the plurality of cache devices according to a predetermined order if the determined popularity is equal to or higher than a reference level. The method according to claim 1,
Wherein the hash key is a result obtained by performing a hash operation on the content identification information with a predetermined hash function and a modulo operation on a hash operation result with a first reference value. The apparatus of claim 1, wherein the relay control unit
The redirection to the selected cache device is requested to the terminal device through the communication interface so that the terminal device transmits a content request message to the selected cache device. The apparatus of claim 1, wherein the relay control unit
And transmits the content request of the terminal apparatus directly to the selected cache apparatus through the communication interface unit. The apparatus of claim 1, wherein the relay control unit
And the mapping information of the storage unit is changed by receiving mapping information between the content hash table and the plurality of cache devices from the communication interface unit according to the logarithmic variation of the plurality of cache devices from the central management device Relay device. The method according to claim 1,
Wherein the relay device is mapped to any one of the plurality of cache devices and implemented as one server. The method according to claim 1,
Wherein the relay device is implemented as a proxy server disposed between the terminal device and the cache devices. The relay device,
Receiving a content request message of the terminal device;
Calculating content identification information of the requested content included in the content request message using a predetermined hash algorithm;
Searching the content hash table for managing the content-based hash key by using the operation result value as a hash key, and confirming the requested content;
A first selection step of selecting, from among the plurality of cache devices, a cache device to process the requested content based on mapping information between the content hash table and a plurality of cache devices;
And controlling the selected cache device to process the requested content. 10. The method of claim 9,
Confirming the popularity of the requested content;
Further comprising a second selection step of selecting one of the plurality of cache devices according to a predetermined order if the popularity of the requested content is higher than a reference level. 10. The method of claim 9,
Requesting the terminal device to redirect the content request to the selected cache device, or directly transmitting the content request to the selected cache device.

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