JPH11224219A - Decentralized cache control method, decentralization controller, decentralizzed cache system, and storage medium stored with decentralized cache control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a decentralized cache control method and decentralization controller, decentralized cache system, and storage medium stored with the decentralized cache control program with high fault tolerance of a fault of a cache device and high process efficiency by having high expansibility corresponding to requests for an increase in communication traffic and an increase in disk capacity for hit rate improvement. SOLUTION: The decentralization controller receives a request from a client S1, calculates the hash value of request resource discrimination information entered into the request S2, selects a cache device corresponding to the hash value by using a decentralization management information S3, and sends the request to the selected cache device S4 and an answer received from the cache device to the client S5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a distributed cache control method, a distributed control apparatus, a distributed cache system, and a storage medium storing a distributed cache control program. The present invention relates to a client / server system such as the Internet or an intranet. Cache system for temporarily storing a copy of information provided by a server between a server and a server, and more particularly, to a distributed cache control method and a distributed control device which are excellent in scalability corresponding to an increase in traffic and excellent in reliability against failures, and The present invention relates to a distributed cache system and a storage medium storing a distributed cache control program.

[0002]

2. Description of the Related Art For example, in the use of the Internet,
In order to enhance the security of the sub-network on the client side, a firewall is generally provided at a connection point between the Internet and the sub-network, and only permitted communication is passed. In addition, a proxy server is installed on the firewall to enable clients on the subnetwork inside the firewall to access the server on the Internet, and communication between the client inside the firewall and the server outside the firewall is established. Relay. In this proxy server, a cache function is generally provided for the purpose of reducing communication traffic between the sub-network and the Internet and shortening the response time to the client. The response sent from the server above is retained in the cache, and if the response requested by the client on the subnetwork exists in the cache, the response in the cache is not sent to the server on the Internet. Send to client.

[0003]

However, the above-mentioned conventional cache method cannot cope with an increase in communication traffic due to an increase in the number of clients. To increase communication traffic, it is conceivable to install a plurality of cache servers (proxy servers) in parallel.
Each client must configure an allocated cache server for the application; to balance the load between cache servers,
A huge amount of man-hour is required to collect load information and reallocate clients; the same response is held on multiple cache servers, wasting disk space; Despite being on the installed cache server, it is not on the cache server that received the request from the client, so the request may be sent to a server on the Internet, reducing the effectiveness of the cache. Problem.

Further, in the conventional cache system, there is a limit on the disk capacity that can be installed, and the hit ratio, which is the ratio of a response corresponding to the cache to the total number of requests from the client, is kept low. The overhead for deleting unnecessary responses to store the responses is large. In the conventional cache method,
If the cache server (proxy server) fails, the relay function between the Internet and the subnetwork is lost, so that clients on the subnetwork cannot access the Internet at all.

[0005] A countermeasure to install a spare cache server for a cache server failure is conceivable, but it is difficult for an individual client to judge a cache server failure; In the event of a failure, the application settings for all clients must be changed to a spare cache server, which requires enormous man-hours; the response held on the failed cache server is completely taken over. The cache hit rate is zero and it takes a long time for the hit rate to recover;
And so on.

In order to solve the above problem, a router intercepts a request to a server on the Internet, selects one of a plurality of cache servers installed corresponding to a destination server address, and makes a request. Has been proposed, but requires a specific router that implements a special protocol with the cache server. The load is not balanced between the cache servers because the assignment of the cache server is performed by the destination server address. The overhead of collecting the load information and reassigning the destination server address is not sufficient to balance the load between the cache servers. Yes, there are problems.

The present invention has been made in view of the above points, and has high expandability in response to a demand for an increase in disk capacity to increase communication traffic and a hit ratio, and has a fault-tolerant property against a failure of a cache device. It is an object of the present invention to provide a distributed cache control method, a distributed control device, a distributed cache system, and a storage medium storing a distributed cache control program, which have high processing efficiency and high processing efficiency.

[0008]

FIG. 1 is a diagram for explaining the principle of the present invention. The present invention (claim 1) provides a distributed cache control method in which one distributed control device controls n cache devices.
A request from a client is received (step 1), a hash value of requested resource identification information described in the request is calculated (step 2), and a cache device corresponding to the hash value is selected using the distribution management information. (Step 3), a request is transmitted to the selected cache device (Step 4), and a response received from the cache device is transmitted to the client (Step 5).

According to the present invention (claim 2), a cache device refers to cache management information using a request received from a client via a distributed control device, and a response corresponding to the request exists in the cache storage means. If the response corresponding to the request does not exist in the cache storage unit, the request is transmitted to the server, and the response corresponding to the request received from the server is stored in the cache storage unit. The distributed control device stores the response, and sends the response received from the cache device to the client.

According to the present invention (claim 3), the n cache devices are divided into n ₁ (n ₁ ≧ 2) operating machines and n ₂ (n ₂ ≧
1) constituted by pre-machine, Normally, when operated with n ₁ single operational machine, one n ₁ single operational machine fails, no
The distributed control device deletes the failed operation device from the distributed management information and adds one of the n ₂ spare devices to the distributed management information, thereby continuing the operation with n ₁ cache devices. .

According to the present invention (claim 4), when one of n (n ≧ 2) cache devices fails, the distribution control device deletes the failed cache device from the distribution management information. By reconfiguring the distributed management information so that the range of hash values assigned to the failed cache device is divided and assigned to the remaining (n-1) cache devices, (n-1) Continue operation with the cache device of

According to the present invention (claim 5), in the distributed control device, the distributed control device cache management information is referred to by using a request from a client, and a response corresponding to the request exists in the distributed control device cache storage means. For example, the corresponding response is transmitted to the client, and if the response corresponding to the request does not exist in the distributed control device cache storage unit, the hash value of the requested resource identification information described in the request is calculated, and the distributed Selecting a cache device corresponding to the hash value using the management information, transmitting a request to the selected cache device, storing a response corresponding to the request received from the cache device in the distributed control device cache storage means, Is registered in the distributed control device cache management information,
Send response to client.

According to the present invention (claim 6), in the distributed control device, the hash value of the requested resource identification information described in the request from the client is calculated, and the hash value is corresponded using the distributed management information. Select a cache device,
Sends a request to the selected cache device, refers to the distributed control device cache management information using the request, and sends a corresponding response to the client if a response corresponding to the request exists in the distributed control device cache storage unit. Then, the response received from the cache device is discarded, and if the response corresponding to the request does not exist in the distributed control device cache storage unit, the response corresponding to the request received from the cache device is stored in the distributed control device cache storage unit. Then, the response is registered in the distributed control device cache management information, and the response is transmitted to the client.

According to the present invention (claim 7), the cache device refers to the cache management information using the request received from the distributed control device, and if a response corresponding to the request exists in the cache storage means, this applies. The response is sent directly to the client, and if the response corresponding to the request does not exist in the cache storage unit, the request is transmitted to the server, the response corresponding to the request received from the server is stored in the cache storage unit, and the response is cached. Register in the management information and send a direct response to the client.

According to the present invention (claim 8), there is provided one distributed control device for controlling n cache devices, wherein the distributed control device receives a request from a client, and receives a request from a client. Hash calculation means for calculating a hash value of the requested resource identification information described in the request; cache device selection means for selecting a cache device corresponding to the hash value by referring to the distribution management information;
Request transmission means for transmitting a request to the selected cache device, response reception means for receiving a response corresponding to the request from the cache device, and response transmission means for transmitting a response to the client.

FIG. 2 is a diagram showing the principle of the present invention. The present invention (claim 9) is a distributed cache system including one distributed control device 5 and n cache devices 6, wherein the distributed control device 5 includes a client request receiving unit 504 for receiving a request from a client. A hash calculation unit 507 that calculates a hash value of the requested resource identification information described in the request received from the client, and a cache device selection unit that selects the cache device 6 corresponding to the hash value by referring to the distribution management information 503 Means 508
A request transmitting unit 509 for transmitting a request to the selected cache device 6, a response receiving unit 510 for receiving a response corresponding to the request from the cache device, and a response transmitting unit 513 for transmitting a response to the client. The cache device 6 determines whether the request receiving unit 603 that receives the request from the distributed control device 5 and whether the response corresponding to the request exists in the cache storage unit 602 by searching the cache management information 601. Means 611 and response reading means 605 for reading the response in the cache storage means 602.
Request transmission means 606 for transmitting a request to the server, server response reception means 607 for receiving a response corresponding to the request from the server, storage means 608 for storing the response in the cache storage means 602, Registration means 609 for registering the correspondence in the cache management information 601;
Response transmitting means 610 for transmitting a response to the distributed control device 5.

The present invention (claim 10) is a distributed cache system comprising one distributed control device and n cache devices, wherein the distributed control device manages the distributed control device cache by using a request from a client. Reference means for referring to information, and in the reference means, if a response corresponding to the request exists in the distributed control device cache storage means, a response transmission means for transmitting the corresponding response to the client;
If a response corresponding to the request does not exist in the distributed control device cache storage unit, a hash value calculating unit that calculates a hash value of the requested resource identification information described in the request; Selection means for selecting a cache device corresponding to the value, request transmission means for transmitting a request to the selected cache device, and storage means for storing a response corresponding to the request received from the cache device in the distributed control device cache storage means Registering means for registering the response in the distributed control device cache management information; and response transmitting means for transmitting the response to the client.

[0018] The present invention (claim 11) is a distributed cache system comprising one distributed control device and n cache devices, wherein the distributed control device includes a request resource described in a request from a client. A hash value calculation unit that calculates a hash value of the identification information, a selection unit that selects a cache device corresponding to the hash value using the distribution management information, a request transmission unit that transmits a request to the selected cache device, A first response transmission unit for referring to the distributed control device cache management information using the request and transmitting a corresponding response to the client if a response corresponding to the request exists in the distributed control device cache storage unit; A response discarding unit for discarding a response received from the server, and a response corresponding to the request does not exist in the distributed control device cache storage unit. Storage means for storing a response corresponding to the request received from the cache device in the distributed control device cache storage means, registration means for registering the response in the distributed control device cache management information, and a second response for transmitting the response to the client Transmission means.

The present invention (claim 12) is a distributed cache system comprising one distributed control device and n cache devices, wherein the cache device uses a request received from the distributed control device to store cache management information. If the response corresponding to the request exists in the cache storage means, the first response transmission means for directly transmitting the corresponding response to the client, and if the response corresponding to the request does not exist in the cache storage means, A second response transmitting unit that transmits a request to the server, a storing unit that stores a response corresponding to the request received from the server in the cache storage unit, a registering unit that registers the response in the cache management information, Third response transmitting means for transmitting to the client.

[0021] The present invention (claim 13) is a storage medium storing a distributed cache control program mounted on one distributed control device for controlling n cache devices, wherein the storage medium stores a request for receiving a request from a client. A receiving process, a hash calculation process for calculating a hash value of the requested resource identification information described in the request received from the client by the request receiving process, and selecting a cache device corresponding to the hash value with reference to the distribution management information And a response transmitting process for transmitting a response to the client, a response receiving process for receiving a response corresponding to the request from the cache device, and a response transmitting process for transmitting the response to the client.

The present invention (claim 14) is a storage medium storing a distributed cache control program in a distributed cache system including one distributed control device and n cache devices, and is mounted on the distributed control device. A client request receiving process for receiving a request from a client, a hash calculation process for calculating a hash value of request resource identification information described in the request received from the client, and a hash value corresponding to the distributed management information. Device selection process for selecting a selected cache device, a request transmission process for transmitting a request to the selected cache device, a response reception process for receiving a response corresponding to the request from the cache device, and a response for transmitting a response to the client And a transmission process. A request receiving process for receiving a request from the distributed control device, a determining process of searching cache management information to determine whether a response corresponding to the request exists in the cache storage unit, A response reading process for reading a response from the server, a request transmitting process for transmitting a request to the server, a server response receiving process for receiving a response corresponding to the request from the server, a storing process for storing the response in the cache storage means, It has a registration process of registering the correspondence with the request in the cache management information, and a response transmission process of transmitting a response to the distributed control device.

The present invention (claim 15) is a storage medium storing a distributed cache control program in a distributed cache system including one distributed control device and n cache devices, and is mounted on the distributed control device. A reference process for referencing the distributed control device cache management information using a request from a client, and in the reference process, if a response corresponding to the request exists in the distributed control device cache storage unit, the corresponding response is transmitted to the client. A response transmission process for causing the request to be transmitted, a hash value calculation process for calculating a hash value of the requested resource identification information described in the request if the response corresponding to the request does not exist in the distributed control device cache storage means, A selection process of selecting a cache device corresponding to the hash value using the management information; A request transmission process for transmitting a request to the selected cache device, a storage process for storing a response corresponding to the request received from the cache device in the distributed control device cache storage unit, and registering the response in the distributed control device cache management information And a response transmission process for transmitting a response to the client.

The present invention (claim 16) is a storage medium storing a distributed cache control program in a distributed cache system comprising one distributed control device and n cache devices, and is mounted on the distributed control device. A hash value calculation process for calculating a hash value of the requested resource identification information described in the request from the client;
Using the distribution management information, a selection process of selecting a cache device corresponding to the hash value, a request transmission process of transmitting a request to the selected cache device, and referring to the distributed control device cache management information using the request, If a response corresponding to the request exists in the distributed control device cache storage means, a first response transmission process for transmitting the response to the client, a response discard process for discarding the response received from the cache device, If the corresponding response does not exist in the distributed control device cache storage unit, a storing process of storing the response corresponding to the request received from the cache device in the distributed control device cache storage unit; and storing the response in the distributed control device cache management information. Registration process for registering with the client, and a second response transmission process for transmitting the response to the client. Have a process.

The present invention (claim 17) is a storage medium storing a distributed cache control program in a distributed cache system comprising one distributed control device and n cache devices, and is mounted on the cache device. A first response transmission process for referencing the cache management information using the request received from the distributed control device and, if a response corresponding to the request exists in the cache storage means, transmitting the corresponding response directly to the client; If a response corresponding to the request does not exist in the cache storage means, a second response transmission process for transmitting a request to the server, a storage process for storing a response corresponding to the request received from the server in the cache storage means, A registration process for registering in the cache management information, and a third response transmission for causing the client to transmit a response And a process.

As described above, in the present invention, the distributed control device receives a request from a client, calculates the hash value of the requested resource identification information described in the request, and refers to the distributed management information. , Selects a cache device corresponding to the hash value, and sends a request to the selected cache device. The cache device receives the request transmitted from the distributed control device, searches the cache management information, and determines whether or not a response corresponding to the request exists in the cache storage unit. When a response corresponding to the request exists in the cache storage unit, the cache device reads the response corresponding to the request from the cache device, and transmits the response to the distributed control device. On the other hand, when the response corresponding to the request does not exist in the cache storage, the cache device transmits the request to the server, receives the response to the request transmitted from the server, stores the response in the cache storage unit, and stores the response in the cache storage unit. Is registered in the cache management information, and the response is transmitted to the distributed control device.

The distributed control device receives the response transmitted from the cache device, and transmits the response to the client.

[0027]

FIG. 3 shows a system configuration to which the present invention is applied. The system shown in FIG. 1 shows the configuration of a client / server system via the Internet. In the client / server system, a client 1 and a server 2 are connected via the Internet 4, and a distributed cache system 3 relays communication between the client 1 and the server 2. As shown in the figure, since only the distributed cache system 3 having the function of the proxy server is visible from the client 1, if the client 1 executes the application only for the distributed cache system 3, Good.

Here, the distributed cache system 3 will be described. FIG. 4 shows the configuration of a distributed cache system to which the present invention is applied. The distributed cache system shown in the figure is an example composed of one distributed control device 5 and four cache devices 6. As shown in the figure, the configuration of one distributed control device 5 and a plurality of (four) cache devices 6 enables the load distribution of the cache device 6 to be distributed.

Further, even when a failure occurs in one cache device, the operation can be continued with the remaining three devices. Further, for example, when the cache devices A, B, and C are configured as operating devices and the cache device D is configured as a standby device, even if a failure occurs in the cache device A, any one of the cache devices D of the standby device is used. It is also possible to substitute for the operation device.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 5 shows the configuration of a distributed cache system according to a first embodiment of the present invention. The distributed cache system shown in FIG. 1 includes a distributed control device 5 and a cache device 6. The distribution control device 5 includes distribution management information 503 for managing a hash value and a cache device corresponding to the hash value, a request receiving unit 504 for receiving a request from the client 1, a request resource identification information URL included in the request. A hash value calculation unit 507 that calculates the hash value of the cache device, a cache device selection unit 508 that selects a cache device corresponding to the obtained hash value with reference to the distribution management information 503, and transfers the request to the selected cache device 6 Request transmitting unit 509, a response receiving unit 510 for receiving a response transmitted from the cache device 6, and a response transmitting unit 513 for transmitting the received response to the client 1.

The cache device 6 includes: cache management information 601 for managing cached information; a cache storage unit 602 for storing cached information; a request receiving unit 603 for receiving a request from the distributed control device 5; A cache management information search unit 6 for obtaining a storage location of cached information based on the information 601
04, a cache storage reading unit 605 for reading cache information from the cache storage unit 602, a request transmission unit 606 for transferring a request to the server 2 when there is no information (response) corresponding to the request in the cache storage unit 601, and a request from the server 2 A response receiving unit 607 for receiving a response corresponding to the request, a cache storage unit 608 for storing the response received from the server 2 in the cache storage unit 601, and cache management information for registering the position information where the response is cached in the cache management information 601. The registration unit 609 includes a response transmission unit 610 that transmits the retrieved and read information or a response from the server 2 to the decentralized management device 5.

The operation of the above configuration will be described below. First, an operation in a case where a response corresponding to a request from the client 1 exists in the cache device 6 will be described. FIG. 6 is a sequence chart in the case where a response corresponding to a request exists (cache device cache hit) in the cache storage unit of the cache device according to the first embodiment of this invention.

When the client 1 transmits a request to the server 2 (step 101), in the distributed control device 5, the request receiving unit 504 receives the request from the client 1 (step 102), and the hash value calculating unit 507 transmits the request in the request. Requested resource identification information URL (Uniform Res
Calculate the hash value of ource Locators) (Step 10
3) The cache device selecting unit 508 determines that the distribution management information 50
3, the cache device 6 corresponding to the hash value is selected (step 104), and the request transmitting unit 509 transmits the request to the selected cache device 6 (step 105).

In the cache device 6, the request receiving unit 603 receives the request transmitted from the distributed control device 5 (step 106), and the cache management information search unit 604 searches the cache management information 601 (step 107). Is determined in the cache storage unit 602, the cache storage read unit 605 reads a response corresponding to the request from the cache device 602 (step 108), and the response transmission unit 610 transmits the response to the distributed control device. 5
(Step 109).

In the distributed control device 5, the response receiving unit 510 receives the response transmitted from the cache device 6 (step 110), and the response transmitting unit 513 transmits the response to the client 1 (step 111). The client 1 receives the response (Step 112). Next, a case where a response corresponding to the request does not exist in the cache storage unit of the cache device 6 will be described.

FIG. 7 is a sequence chart at the time of a cache miss in the cache device according to the first embodiment of the present invention. When the client 1 transmits a request to the server 2 (step 201), in the distributed control device 5, the request receiving unit 504 receives the request from the client 1 (step 202), and the hash value calculation unit 507 is described in the request. The hash value of the requested resource identification information URL is calculated (step 203), and the cache device selecting unit 508 refers to the distribution management information 503 to select the cache device 6 corresponding to the hash value (step 204). The transmitting unit 509 transmits the request to the selected cache device 6 (Step 205).

In the cache device 6, the request receiving unit 603 receives the request transmitted from the distributed control device 5 (step 206), and the cache management information search unit 604 searches the cache management information 601 (step 207). It is determined that no response corresponding to the request exists in the cache storage unit 602, and the request transmission unit 606 transmits the request to the server 2 (Step 208), and the server 2 receives this (Step 209). The server 2 sends a response to the request to the cache device 6 (Step 210). The response receiving unit 607 of the cache device 6 receives a response corresponding to the request transmitted from the server 2 (step 211),
The cache storage unit 608 stores the response in the cache storage unit 602 (step 212), and the cache management information registration unit 609 registers the correspondence between the response and the request stored in the cache storage unit 602 in the cache management information 601 ( (Step 213), the response transmitting unit 610 transmits the response to the distributed control device 5 (Step 214).

In the distributed control device 5, the response receiving unit 510 receives the response transmitted from the cache device 6 (step 215), and the response transmitting unit 513 transmits the response to the client 1 (step 216). Client 1
The response is received (step 217). [Second Embodiment] In this embodiment, the cache device group is set to n.
It is composed of _one (n ₁ ≧ 2) operation units and n ₂ (n ₂ ≧ 1) standby units. Normally, the operation unit is operated using n ₁ operation units, and the operation unit fails. In the following, an example will be described in which the operation device is deleted from the distributed management information, and n ₂ spare devices are additionally registered in the distributed management information, thereby operating the device with n ₁ cache devices.

FIG. 8 shows the structure of the distributed management information according to the second embodiment of the present invention. The distributed cache system includes one distributed control device, four cache device operating devices (A, B, C, D) and two cache device spare devices (E, F). . The contents of the distribution management information 503 before the occurrence of the failure are such that the hash value range for the cache device A is “000000 to 3FFFFFF” and the hash value range corresponding to the cache device B is “400000 to 30000”.
7FFFFF ”, the hash value range corresponding to the cache device C is“ 800000 to BFFFFFF ”, and the hash value range corresponding to the cache device D is“ C0000 to F0000F ”.
FFFFF ". When the operation device B fails, the entry of the operation device B is deleted from the distribution management information 503, the entry of the spare device F is added, and the hash value range corresponding to the cache device F is set to "400000 to 7FFFFF". The operation is continued with the four cache devices (operating machines A, C, and D and the old spare machine F).

[Third Embodiment] In this embodiment, n units (n
If one of the cache devices of ≧ 2) fails, the distribution control device deletes the failed cache device from the distribution management information and sets the range of the hash value assigned to the failed cache device. An example in which the distributed management information is reconfigured so as to be divided and assigned to the remaining (n-1) cache devices will be described.

FIG. 9 shows the structure of the distributed management information according to the third embodiment of the present invention. The distributed cache system has one distributed control device and four cache devices (A, B,
C, D). The contents of the distribution management information 503 before the failure occurs are as follows. The hash value range corresponding to the cache device A is “000000 to 3FFFFFF”, and the hash value range corresponding to the cache device B is “400000 to 7”.
FFFFF ”, the hash value range corresponding to the cache device C is“ 800000 to BFFFFF ”, and the hash value range corresponding to the cache device D is“ C0000 to FF ”.
FFFF ". If the cache device B fails,
The entry of the cache device B is deleted from the distribution management information 503, and the hash value range “400000 to 7FFFFF” corresponding to the cache device B is additionally assigned to the remaining three cache devices (A, C, D). The operation is continued with the two cache devices (A, C, D). The content of the distribution management information 503 after the occurrence of the failure indicates that the hash value range corresponding to the cache device A is “000000 to 3FFFF”.
F "and" 400000-555554 ", and the hash value range corresponding to the cache device C is" 800000-B ".
FFFFF ”and“ 555555-6AAAA9 ”, and the hash value range corresponding to the cache device D is“ C000
00-FFFFFF "and" 6AAAAA-7FFFF "
F ".

[Fourth Embodiment] FIG. 10 shows a fourth embodiment of the present invention.
FIG. 2 is a configuration diagram of a distributed cache system according to an embodiment.
The distributed cache system shown in FIG. 1 includes a cache device 6 and a distributed control device 5. Distributed control device 5
Are the cache management information 501 and the cache storage unit 50
2, distribution management information 503, request reception unit 504, cache management information search unit 505, cache storage reading unit 50
6, hash value calculation unit 507, cache device selection unit 5
08, request transmission unit 509, response reception unit 510, cache storage unit 511, cache management information registration unit 51
2 and a response transmission unit 513.

The cache device 6 includes cache management information 601, a cache storage unit 602, a request reception unit 603,
Cache management information search unit 604, cache storage read unit 605, request transmission unit 606, response reception unit 607, cache storage unit 608, cache management information registration unit 6
09, and a response transmission unit 610. The above-described configuration shown in FIG. 5 includes cache management information 501, a cache storage unit 502, a cache management information search unit 505, a cache storage read unit 506,
This is a configuration in which a cache storage unit 511 and a cache management information registration unit 512 are provided, and is an example in which a part of information cached in all the cache devices 6 in the distributed control device 5 is grasped.

Next, the operation of the above configuration will be described. First, a case where a response corresponding to a request from the client 1 exists in the distributed control device 5 will be described. FIG. 11 is a sequence chart at the time of a cache hit of the distributed control apparatus according to the fourth embodiment of this invention.

When the client 1 sends a request to the server 2 (step 301), in the distributed control device 5, the request receiving unit 504 receives the request from the client 1 (step 302), and the cache management information searching unit 505
Searches the cache management information 501 (step 30).
3) It is determined that a response corresponding to the request exists in the cache storage unit 502, and the cache storage read unit 506 is determined.
Reads the response corresponding to the request from the cache storage unit 502 (step 304), and the response transmission unit 513 transmits the response to the client 1 (step 30).
5). The client 1 receives the response (Step 306).

Next, a case where there is no response corresponding to the request in the distributed control device 5 and there is a response in the cache device 6 will be described. FIG. 12 is a sequence chart at the time of a cache miss and a cache hit of the distributed control apparatus according to the fourth embodiment of the present invention. When the client 1 transmits a request to the server 2 (step 401), in the distributed control device 5, the request receiving unit 504 receives the request from the client 1 (step 402), and the cache management information searching unit 505 sets the cache management information 5
01 (step 403), it is determined that a response corresponding to the request does not exist in the cache storage unit 502, and the hash value calculation unit 507 determines whether the request resource identification information URL described in the request is The hash value is calculated (step 404), the cache device selection unit 508 selects the cache device 6 corresponding to the hash value with reference to the distribution management information 503 (step 405), and the request transmission unit 509 selects the selected cache device. 6 is transmitted to the request (step 406).

In the cache device 6, the request receiving unit 603 receives the request transmitted from the distributed control device 5 (step 407), and the cache management information search unit 604 searches the cache management information 601 (step 408). It is determined that a response corresponding to the request exists in the cache storage unit 602, the cache storage reading unit 605 reads a response corresponding to the request from the cache storage unit 602 (step 409), and the response transmission unit 610 determines the response Is transmitted to the distributed control device 5 (step 410).

In the distributed control device 5, the response receiving unit 510 receives the response transmitted from the cache device 6 (step 411), and the cache storage unit 511 stores the response in the cache storage unit 502 (step 412). The correspondence between the response stored in the cache storage unit 502 and the request is registered in the cache management information 501 by the cache management information registration unit 512 (step 413), and the response transmission unit 5
13 transmits the response to the client 1 (step 414). The client 1 receives the response (Step 415).

Next, an example in which neither the distributed control device 5 nor the cache device 6 has a response corresponding to the request will be described. FIG. 13 and FIG. 14 are sequence charts at the time of a cache miss of the distributed control device and a cache miss of the cache device according to the fourth embodiment of the present invention. When the client 1 transmits a request to the server 2 (step 501), the distributed control device 5 causes the request receiving unit 504 to receive the request from the client 1 (step 502).
The cache management information search unit 505 searches the cache management information 501 (step 503), determines that the response corresponding to the request does not exist in the cache storage unit 502, and the hash value calculation unit 507 writes the response in the request. The hash value of the requested resource identification information URL is calculated (step 504), and the cache device selecting unit 508 selects the cache device 6 corresponding to the hash value by referring to the distribution management information 503 (step 505). The transmitting unit 509 transmits the request to the selected cache device 6 (Step 506).

In the cache device 6, the request receiving unit 603 receives the request transmitted from the distributed control device 5 (step 507), and the cache management information search unit 604 searches the cache management information 601 (step 508). It is determined that the response corresponding to the request does not exist in the cache storage unit 602, the request transmitting unit 606 transmits the request to the server 2 (Step 509), and the server 2 receives the request (Step 510). . The server 2 transmits a response corresponding to the request to the cache device 6 (Step 511).

In the cache device 6, the response receiving unit 607 receives the response corresponding to the request transmitted from the server 2 (step 512), and the cache storage unit 608 stores the response in the cache storage unit 602 (step 512). Step 513), the correspondence between the response and the request stored in the cache storage unit 602 by the cache management information registration unit 609 is registered in the cache management information 601 (Step 514).
The response transmitting unit 610 transmits the response to the distributed control device 5 (Step 515).

In the distributed control device 5, the response receiving unit 510 receives the response transmitted from the cache device 6 (step 516), and the cache storage unit 511 stores the response in the cache storage unit 502 (step 51).
7) The cache management information registration unit 512 registers the correspondence between the response and the request stored in the cache storage unit 502 in the cache management information 501 (step 518), and the response transmission unit 513 sends the response to the client 1 (step 518). 519). The client 1 receives the response (Step 520).

[Fifth Embodiment] FIG. 15 shows a fifth embodiment of the present invention.
1 shows a configuration of a distributed cache system according to an embodiment. The distributed cache system shown in FIG. 1 includes a cache device 6 and a distributed control device 5. Distributed control device 5
Are the cache management information 501 and the cache storage unit 50
2, distribution management information 503, request reception unit 504, cache management information search unit 505, cache storage reading unit 50
6, hash value calculation unit 507, cache device selection unit 5
08, request transmission unit 509, response reception unit 510, cache storage unit 511, cache management information registration unit 51
2. It comprises a response transmission unit 513 and a response discard unit 514.

The cache device 6 includes cache management information 601, a cache storage unit 602, a request reception unit 603,
Cache management information search unit 604, cache storage reading unit 605, request transmission unit 606, response reception unit 607, cache storage storage unit 608, cache management information registration unit 60
9 and a response transmission unit 610. The configuration shown above is a configuration in which a response discarding unit 514 is added to the distributed control device 5 shown in FIG.
In the distributed control device 5, when a response corresponding to the request exists in the cache storage unit 502, the response acquired from the cache device 6 can be discarded.

Next, the operation of the above configuration will be described.
First, a case where a response corresponding to a request from the client 1 exists in the distributed control device 5 will be described. FIG. 16 is a sequence chart at the time of a cache hit of the distributed control apparatus according to the fifth embodiment of the present invention.

When the client 1 transmits a request to the server 2 (step 601), in the distributed control device 5, the request receiving section 504 receives the request from the client 1 (step 602), and the hash value calculating section 507 sends the request to the request. (Step 603), and calculates the hash value of the requested resource information URL described in
08 selects the cache device 6 corresponding to the hash value with reference to the distribution management information 503 (step 604), and the request transmission unit 509 transmits a request to the selected cache device 6 (step 605), and the cache management information The search unit 505 searches the cache management information 501 (step 606), determines that a response corresponding to the request exists in the cache storage unit 502, and
06 reads a response corresponding to the request from the cache storage unit 502 (step 607), and the response transmission unit 513 transmits the response to the client 1 (step 608). The client 1 receives the response (step 60).
9).

In the cache device 6, the request receiving unit 603 receives the request transmitted from the distributed control device 5 (step 610), and the cache management information search unit 604 searches the cache management information 601 (step 611). It is determined that a response corresponding to the request exists in the cache storage unit 602, the cache storage reading unit 605 reads a response corresponding to the request from the cache storage unit 602 (step 612), and the response transmission unit 610 determines the response. The response is transmitted to the distributed control device 5 (step 613). In the distributed control device 5, the response receiving unit 510 receives the response transmitted from the cache device 6 (Step 614), and the response discarding unit 514 discards the response (Step 615).

Next, a case will be described in which the distributed control device 5 has no response corresponding to the request from the client 1 and the cache device has a response. FIG. 17 is a sequence chart at the time of a cache miss and a cache hit of the distributed control apparatus according to the fifth embodiment of the present invention. When the client 1 transmits a request to the server 2 (step 701), in the distributed control device 5, the request receiving unit 504 receives the request from the client 1 (step 702), and the hash value calculation unit 507 is described in the request. The hash value of the requested resource identification information URL is calculated (step 703), and the cache device selection unit 508 selects the cache device 6 corresponding to the hash value with reference to the distribution management information 503 (step 704), and transmits the request. The unit 509 sends a request to the selected cache device 6 (step 705), and the cache management information search unit 505
Searches the cache management information 501 (step 70).
6), a response corresponding to the request is stored in the cache storage unit 50;
2 is not present.

In the cache device 6, the request receiving unit 603 receives the request transmitted from the distributed control device 5 (step 707), and the cache management information search unit 604 searches the cache management information 601 (step 708). It is determined that a response corresponding to the request exists in the cache storage unit 602, the cache storage reading unit 605 reads a response corresponding to the request from the cache storage unit 602 (Step 709), and the response transmission unit 610 determines The response is transmitted to the distributed control device 5 (step 710).

In the distributed control device 5, the response receiving unit 510 receives the response transmitted from the cache device 6 (step 711), and the cache storage unit 511 stores the response in the cache storage unit 502 (step 712). , The cache management information registration unit 512
2 is registered in the cache management information 501 (step 713), and the response transmitting unit 513 transmits the response to the client 1 (step 714). The client 1 receives the response (Step 715).

Next, a case will be described in which neither the distributed control device 5 nor the cache device 6 has a response corresponding to the request. FIGS. 18 and 19 are sequence charts at the time of a cache miss and a cache miss in the distributed control device according to the fifth embodiment of the present invention. When the client 1 transmits a request to the server 2 (step 801), in the distributed control device 5, the request receiving unit 504 receives the request from the client 1 (step 802), and the hash value calculating unit 507 writes the request in the request. The hash value of the requested resource identification information URL is calculated (step 803), and the cache device selecting unit 508 selects the cache device 6 corresponding to the hash value with reference to the distribution management information 503 (step 804). The transmission unit 509 transmits the request to the selected cache device 6 (step 805), and the cache management information search unit 5
05 searches the cache management information 501 (step 806), and a response corresponding to the request is stored in the cache storage unit 5
02 is not present.

In the cache device 6, the request receiving unit 603 receives the request transmitted from the distributed control device 5 (step 807), and the cache management information search unit 604 searches the cache management information 601 (step 808). ,
It is determined that the response corresponding to the request does not exist in the cache storage unit 602, the request transmitting unit 606 transmits the request to the server 2 (Step 809), and the server 2 receives the request (Step 810). .

The server 2 sends a response corresponding to the request to the cache device 6 (Step 811). The response receiving unit 607 of the cache device 6 receives the response corresponding to the request transmitted from the server 2 (Step 812),
The cache storage unit 608 stores the response in the cache storage unit 602 (step 813), and the cache management information registration unit 609 stores the correspondence between the response stored in the cache storage unit 602 and the request in the cache management information 6.
01 (step 814), and the response transmitting unit 610 transmits the response to the distributed control device 5 (step 81).
5).

In the distributed control device 5, the response receiving unit 510 receives the response transmitted from the cache device 6 (step 816), and the cache storage unit 511 stores the response in the cache storage unit 502 (step 817). , The cache management information registration unit 512
2 is registered in the cache management information 501 (step 818), and the response transmission unit 513 transmits the response to the client 1 (step 819). The client 1 receives the response (Step 820).

[Sixth Embodiment] FIG. 20 shows a sixth embodiment of the present invention.
1 shows a configuration of a distributed cache system according to an embodiment. The distributed cache system shown in FIG.
And a cache device 6. Distributed control device 5
Has distribution management information 503, a request receiving unit 504, a hash value calculating unit 507, a cache device selecting unit 508, and a request transmitting unit 509.

The cache device 6 includes cache management information 601, a cache storage unit 602, a request reception unit 603,
It has a cache management information search unit 604, a cache storage read unit 605, a request transmission unit 6060, a response reception unit 607, a cache storage unit 608, a cache management information registration unit 609, and a response transmission unit 610. The configuration shown in the figure is the same as the configuration shown in FIG. 5 except that the response receiving unit 510 and the response transmitting unit 513 are removed from the configuration shown in FIG. This configuration allows the response to be transmitted directly to the client 1 without going through.

Next, the operation of the above configuration will be described.
First, a case where a response corresponding to a request exists in the cache device 6 will be described. FIG. 21 is a sequence chart at the time of a cache hit in the cache device according to the sixth embodiment of the present invention.

When the client 1 sends a request to the server 2 (step 901), in the distributed control device 5, the request receiving unit 504 receives the request from the client 1 (step 902), and the hash value calculating unit 507 sends the request to the request. (Step 903), and the cache device selecting unit 508 refers to the distribution management information 503 and selects the cache device 6 corresponding to the hash value (Step 903). 90
4), the cache device 6 in which the request transmission unit 509 is selected
(Step 905).

In the cache device 6, the request receiving unit 603 receives the request transmitted from the distributed control device 5 (step 906), and the cache management information search unit 604 searches the cache management information 601 (step 907). ,
It is determined that a response corresponding to the request exists in the cache storage unit 602, the cache storage reading unit 605 reads a response corresponding to the request from the cache storage unit 602 (step 908), and the response transmission unit 601 determines Is transmitted to the client 1 (step 909). The client 1 receives the response (Step 910).

Next, the case where there is no response corresponding to the request in the cache device 6 will be described. FIG. 22 is a sequence chart at the time of a cache miss in the cache device according to the sixth embodiment of the present invention. When the client 1 sends a request to the server 2 (step 1001),
In the distributed control device 5, the request receiving unit 504
(Step 1002), the hash value calculation unit 507 calculates the hash value of the requested resource identification information URL described in the request (Step 1003),
The cache device selecting unit 508 selects the cache device 6 corresponding to the hash value with reference to the distribution management information 503 (Step 1004), and the request transmitting unit 509 transmits a request to the selected cache device 6 (Step 100).
5).

In the cache device 6, the request receiving unit 603 receives the request transmitted from the distributed control device 5 (step 1006), and the cache management information search unit 604 searches the cache management information 601 (step 1007).
It is determined that the request does not exist in the cache storage unit 602 corresponding to the request, the request transmitting unit 606 transmits the request to the server 2 (step 1008), and the server 2 receives the request (step 1009), and The corresponding response is returned to the cache device 6 (Step 1010).

The response receiving unit 607 of the cache device 6 receives a response corresponding to the request transmitted from the server 2 (step 1011), and the cache storage unit 608 stores the response in the cache storage unit 602 (step 101).
2) The cache management information registration unit 609 registers the correspondence between the response and the request stored in the cache storage unit 602 in the cache management information 601 (step 1013), and the response transmission unit 610 transmits the response to the client 1 (step 1013). Step 1014). Client 1 receives the response (step 1015).

Further, a method for controlling a cache device to be distributed and a method for controlling a cache device by the distributed control device in the above embodiment are constructed as a program, and a disk device connected to the distributed control device and the cache device, a floppy disk, and the like. The present invention can be easily realized by storing the program in a portable storage medium such as a disk or a CD-ROM and installing the program when implementing the present invention.

In the above embodiment, the response in the cache storage unit is unconditionally transmitted to the client at the time of a cache hit of the distributed control device or the cache device. However, according to the current general cache control method, the cache is not cached. Manages the "fresh period" for each response
If it is within the "fresh period" at the time of the hit, after asking the server whether the response inside the cache memory is the latest,
Send the latest response to the client. Also in the present invention, it is possible to set a fresh period as described above and apply a similar method.

The present invention is not limited to the above embodiment, but can be variously modified and applied within the scope of the claims.

[0076]

As described above, according to the present invention, a distributed cache system is composed of one distributed controller and n distributed controllers (n ≧ n).
Since it is composed of the cache device of 2), the load of the cache device can be distributed and the cache
It is possible to realize a server.

If one of the n cache devices fails, the remaining (n-1) cache devices may be configured to continue operation, or a spare machine may be prepared to handle the failure. It is also possible to configure the system so that the operation can be continued with n units by replacing the used operation unit with a spare unit, and a cache server with high fault tolerance can be realized.

Further, if one of the n cache devices fails, the information in the cache storage held by the remaining (n-1) cache devices can be continuously used. It is possible to minimize the decrease in the hit rate due to Also, since only the distributed control device can be seen from the client as a proxy server, the number of cache devices decreases due to failure or maintenance, the operating device is replaced with a spare device, or the performance is improved. Even if the number of cache devices increases, it is not necessary to change the settings of the client application.

Further, since the load distribution to the n cache devices is performed using the hash value calculated from the requested resource identification information such as the URL, the load is evenly distributed, and the monitoring of the load status of each cache device is performed. Further, it is not necessary to reassign the correspondence between the request and the cache device. Further, by installing a primary cache memory in the distributed control device and holding information with a high access frequency or information with a short cache period, the response time of the client can be further improved.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the principle of the present invention.

FIG. 2 is a principle configuration diagram of the present invention.

FIG. 3 is a system configuration diagram to which the present invention is applied.

FIG. 4 is a configuration diagram of a distributed cache system to which the present invention is applied.

FIG. 5 is a configuration diagram of a distributed cache system according to the first embodiment of this invention.

FIG. 6 is a sequence chart in a case where a response corresponding to a request exists in the cache storage unit of the cache device according to the first embodiment of this invention.

FIG. 7 is a sequence chart in the case where a response corresponding to a request exists in the cache storage unit of the cache device according to the first embodiment of this invention.

FIG. 8 is a configuration diagram of distributed management information according to the second embodiment of this invention.

FIG. 9 is a configuration diagram of distributed management information according to a third embodiment of this invention.

FIG. 10 is a configuration diagram of a distributed cache system according to a fourth embodiment of the present invention.

FIG. 11 is a sequence chart at the time of a cache hit of the distributed control apparatus according to the fourth embodiment of the present invention.

FIG. 12 is a sequence chart for a distributed control device cache miss and a cache device cache hit according to the fourth embodiment of this invention.

FIG. 13 is a sequence chart (No. 1) at the time of a distributed control device cache miss and a cache device cache miss according to the fourth embodiment of this invention.

FIG. 14 is a sequence chart (No. 2) at the time of a distributed control device cache miss and a cache device cache miss according to the fourth embodiment of this invention.

FIG. 15 is a configuration diagram of a distributed cache system according to a fifth embodiment of the present invention.

FIG. 16 is a sequence chart at the time of a cache hit of the distributed control apparatus according to the fifth embodiment of the present invention.

FIG. 17 is a sequence chart for a distributed control device cache miss and a cache device cache hit according to the fifth embodiment of the present invention.

FIG. 18 is a sequence chart (No. 1) of a distributed control device cache miss and a cache device cache miss according to the fifth embodiment of the present invention.

FIG. 19 is a sequence chart (part 2) of the distributed control device cache miss and the cache device cache miss according to the fifth embodiment of the present invention.

FIG. 20 is a configuration diagram of a distributed cache system according to a sixth embodiment of the present invention.

FIG. 21 is a sequence chart at the time of a cache hit in the cache device according to the sixth embodiment of the present invention.

FIG. 22 is a sequence chart at the time of a cache miss in the cache device according to the sixth embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 1 client 2 server 3 distributed cache system 4 Internet 5 distribution control device 6 cache device 501 cache management information 502 cache storage unit 503 distribution management information 504 request reception unit, request reception unit 505 cache management information search unit 506 cache storage read unit 507 hash Value calculation unit, hash calculation unit 508 cache device selection unit, cache device selection unit 509 request transmission unit, request transmission unit 510 response reception unit, response reception unit 511 cache storage unit 512 cache management information registration unit 513 response transmission unit, response Transmission unit 514 Response discard unit 601 Cache management information 602 Cache storage unit, cache storage unit 603 Request reception unit, request reception unit 604 Cache management information search unit 605 Cache Queue storage readout unit, response readout unit 606 request transmission unit, request transmission unit 607 response reception unit, server response reception unit 608 cache storage storage unit, storage unit 609 cache management information registration unit, registration unit 610 response transmission unit, response transmission unit 611 determination means

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[Procedure amendment]

[Submission date] February 6, 1998

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

FIG. 2

Claims (17)

[Claims] 1. A distributed cache control method for controlling n cache devices by one distributed control device, wherein the distributed control device receives a request from a client, and identifies a request resource described in the request. Calculating a hash value of the information, using the distribution management information, selecting the cache device corresponding to the hash value, transmitting the request to the selected cache device, and transmitting a response received from the cache device to the cache device. A distributed cache control method, wherein the method is transmitted to a client. 2. The cache device refers to cache management information using the request received from the client via the distributed control device, and if a response corresponding to the request exists in a cache storage unit, Transmitting a corresponding response to the distributed control device; if a response corresponding to the request does not exist in the cache storage unit, transmitting the request to a server; and transmitting a response corresponding to the request received from the server. 2. The distributed cache control method according to claim 1, wherein the response is stored in the cache storage unit, the response is transmitted to the distributed control device, and the response received from the cache device by the distributed control device is transmitted to the client. The method according to claim 3, wherein the n-number of the cache device, n _one (n ₁ ≧ 2) Operation unit and n ₂ units composed of (n ₂ ≧ 1) spare machine, usually, the n _single When the operation is performed using an operation device and _{one of the} n ₁ operation devices fails, the distributed control device deletes the failed operation device from the distributed management information. by adding one of the _two spare machine in the distributed management information, distributed cache control method according to claim 1 or 2 wherein continue to operate at n ₁ single cache device. 4. When one of n (n ≧ 2) cache devices has failed, the distributed control device deletes the failed cache device from the distribution management information, and By reconfiguring the distribution management information so that the range of the hash value assigned to the changed cache device is divided and assigned to the remaining (n-1) cache devices, the (n-1) 3. The distributed cache control method according to claim 1, wherein the operation is continued in the cache device. 5. The distributed control device refers to the distributed control device cache management information using a request from the client, and if a response corresponding to the request exists in the distributed control device cache storage unit, Transmitting a response to the client; if a response corresponding to the request does not exist in the distributed control device cache storage unit, calculating a hash value of the requested resource identification information described in the request; Selecting the cache device corresponding to the hash value using management information; transmitting the request to the selected cache device; and transmitting a response corresponding to the request received from the cache device to the distributed control device cache. Storing the response in the distributed control device cache management information; and storing the response in the client. Claim transmits 1 to 4
The distributed cache control method as described above. 6. The distribution control device calculates a hash value of requested resource identification information described in a request from the client, and uses the distribution management information to set the cache device corresponding to the hash value. And sends the request to the selected cache device, refers to the distributed control device cache management information using the request, and if a response corresponding to the request exists in the distributed control device cache storage unit. Transmitting the corresponding response to the client, discarding the response received from the cache device, and if the response corresponding to the request does not exist in the distributed control device cache storage unit, the response received from the cache device. A response corresponding to the request is stored in the distributed control device cache storage means, and the response is stored in the distributed control device cache memory. Registered in the information, it claims 1 to 4 for transmitting the response to the client
The distributed cache control method as described above. 7. The cache device refers to cache management information using the request received from the distributed control device. If a response corresponding to the request exists in the cache storage unit, the cache device determines the corresponding response. If the response corresponding to the request is transmitted directly to the client and the response corresponding to the request does not exist in the cache storage unit, the request is transmitted to the server, and the response corresponding to the request received from the server is stored in the cache storage unit. 5. The distributed cache control method according to claim 1, wherein the response is stored, the response is registered in the cache management information, and the response is directly transmitted to the client. 8. A distributed control device for controlling n cache devices, wherein the distributed control device includes: a request receiving unit that receives a request from a client; and a request receiving unit that receives a request from the client. Hash calculation means for calculating a hash value of the requested resource identification information, cache device selection means for selecting a cache device corresponding to the hash value with reference to distribution management information, and requesting the selected cache device for the request. And a response transmitting means for transmitting a response corresponding to the request from the cache device, and a response transmitting means for transmitting the response to the client. 9. A distributed cache system comprising one distributed control device and n cache devices, wherein the distributed control device comprises: a client request receiving means for receiving a request from a client; Hash calculation means for calculating a hash value of the requested resource identification information described in the request; cache device selection means for selecting a cache device corresponding to the hash value by referring to distribution management information; Request transmitting means for transmitting the request to the device; response receiving means for receiving a response corresponding to the request from the cache device; and response transmitting means for transmitting the response to the client. Request receiving means for receiving a request from the distributed control device; Determining means for determining whether a response corresponding to the request exists in the cache storage means, response reading means for reading the response in the cache storage means, and request transmission for transmitting the request to a server Means, server response receiving means for receiving a response corresponding to the request from the server, storage means for storing the response in the cache storage means, and a correspondence relationship between the response and the request in the cache management information. A distributed cache system comprising: registration means for registering; and response transmission means for transmitting the response to the distributed control device. 10. A distributed cache system comprising one distributed control device and n cache devices, wherein the distributed control device refers to distributed control device cache management information using a request from the client. Means, if the response corresponding to the request is present in the distributed control device cache storage means, the response transmitting means for transmitting the corresponding response to the client; and the response corresponding to the request is the distributed If it does not exist in the control device cache storage unit, a hash value calculation unit that calculates a hash value of the requested resource identification information described in the request, and the hash value corresponding to the hash value using the distribution management information Selecting means for selecting a cache device; request transmitting means for transmitting the request to the selected cache device; A storage unit for storing a response corresponding to the request received from the cache device in the distributed control device cache storage unit; a registration unit for registering the response in the distributed control device cache management information; and transmitting the response to the client. A distributed cache system comprising: a response transmitting unit that transmits a response. 11. A distributed cache system comprising one distributed control device and n cache devices, wherein the distributed control device has a hash value of requested resource identification information described in a request from the client. A hash value calculation unit that calculates the hash value, a selection unit that selects the cache device corresponding to the hash value, and a request transmission unit that transmits the request to the selected cache device. A first response transmission unit for referring to the distributed control device cache management information using the request and transmitting a corresponding response to the client if a response corresponding to the request exists in the distributed control device cache storage unit; A response discarding unit that discards a response received from the cache device; and a response corresponding to the request is the distributed control device key. If it does not exist in the cache storage unit, a storage unit that stores a response corresponding to the request received from the cache device in the distributed control device cache storage unit; and registers the response in the distributed control device cache management information. A distributed cache system comprising: a registration unit; and a second response transmission unit that transmits the response to the client. 12. A distributed cache system comprising one distributed control device and n cache devices, wherein the cache device refers to cache management information using the request received from the distributed control device, If a response corresponding to the request exists in the cache storage unit, a first response transmission unit that directly transmits the corresponding response to the client; and a response corresponding to the request must exist in the cache storage unit. For example, a second response transmission unit that transmits the request to the server, a storage unit that stores a response corresponding to the request received from the server in the cache storage unit, and registers the response in the cache management information. And a third response transmitting means for directly transmitting the response to the client. Scatter cache system. 13. A storage medium storing a distributed cache control program mounted on one distributed control device for controlling n cache devices, a request receiving process for receiving a request from a client, and the request receiving process. A hash calculation process for calculating a hash value of request resource identification information described in the request received from the client by a process, and a cache device for selecting a cache device corresponding to the hash value by referring to distribution management information A storage medium storing a distributed cache control program, comprising: a selection process; a response reception process for receiving a response corresponding to the request from the cache device; and a response transmission process for transmitting the response to the client. . 14. A storage medium storing a distributed cache control program in a distributed cache system comprising one distributed control device and n cache devices, wherein a request is received from a client mounted on the distributed control device. A client request receiving process, a hash calculation process for calculating a hash value of request resource identification information described in the request received from the client, and a cache device corresponding to the hash value with reference to distribution management information And a response transmitting process for transmitting the response to the client, the response receiving process for receiving a response corresponding to the request from the cache device, and a response transmitting process for transmitting the response to the client. Receiving a request from the distributed controller A request receiving process for determining whether a response corresponding to the request is present in the cache storage unit by searching cache management information, and a response reading process for reading a response in the cache storage unit. A request transmitting process for transmitting the request to the server; a server response receiving process for receiving a response corresponding to the request from the server; a storing process for storing the response in the cache storage unit; the response and the request A storage medium storing a distributed cache control program, comprising: a registration process of registering a correspondence between the distributed cache device and the cache management information; and a response transmission process of transmitting the response to the distributed control device. 15. A storage medium storing a distributed cache control program in a distributed cache system comprising one distributed control device and n cache devices, wherein the request from the client is mounted on the distributed control device. A reference process for referring to the distributed control device cache management information by using: a response for transmitting the corresponding response to the client if a response corresponding to the request exists in the distributed control device cache storage unit in the reference process. A transmission process, and if a response corresponding to the request does not exist in the distributed control device cache storage unit, a hash value calculation process of calculating a hash value of the requested resource identification information described in the request; The cache device corresponding to the hash value is selected using the distribution management information. A requesting process for transmitting the request to the selected cache device; a storing process for storing a response corresponding to the request received from the cache device in the distributed control device cache storage unit; A storage medium storing a distributed cache control program, comprising: a registration process for registering the response in the distributed control device cache management information; and a response transmission process for transmitting the response to the client. 16. A storage medium storing a distributed cache control program in a distributed cache system comprising one distributed control device and n cache devices, wherein the request from the client is mounted on the distributed control device. A hash value calculation process of calculating a hash value of the requested resource identification information described in, a selection process of selecting the cache device corresponding to the hash value using the distribution management information, A request transmitting process for transmitting the request to the cache device, and referring to the distributed control device cache management information using the request, and if a response corresponding to the request exists in the distributed control device cache storage unit, the corresponding response A first response transmission process for causing the client to transmit A response discarding process for discarding a response received from the distributed control device, if a response corresponding to the request does not exist in the distributed control device cache storage unit, a response corresponding to the request received from the cache device is transmitted to the distributed control device. A distribution process for storing the response in the cache storage unit; a registration process for registering the response in the distributed control device cache management information; and a second response transmission process for directly transmitting the response to the client. A storage medium storing a cache control program. 17. A storage medium storing a distributed cache control program in a distributed cache system including one distributed control device and n cache devices, the storage medium being mounted on the cache device and receiving from the distributed control device. Referring to the cache management information using the request, and if a response corresponding to the request exists in the cache storage unit, a first response transmission process for directly transmitting the corresponding response to the client; If a response corresponding to the request does not exist in the cache storage means, a second request to transmit the request to the server
Transmitting a response corresponding to the request received from the server in the cache storage unit; registering the response in the cache management information; and transmitting the response directly to the client. A storage medium storing a distributed cache control program, characterized by having a third response transmission process for transmitting.