JPH08263418A - System and method for resource access - Google Patents

Abstract

PURPOSE: To access to an arbitrary resource without being conscious at all of the name of a server with resources managed by a client when performing access form the client to any desired resource in a distributed resource managing system where plural servers distributedly manage the resources of a data base, memory table and file or the like. CONSTITUTION: A resource name server RN performs the centralized management of all the resources in the system and server names to manage those resources on a resource name table 14. When accessing from a client 11 to a certain resource F, first of all, the server name managing that resource F is inquired to the resource name server RN (S13) and that server name 'server B' is possessed (S16). Next, the client 11 issues the instruction of access to the resource F to the server B having that possessed server name (S17). In order to possess the server name at high speed, the client 11 is desirably provided with a local cache table 15 and the resource names and server names inquired in the last are registered here.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resource access method for a client to access a desired resource in a distributed resource management system in which a plurality of servers manage resources such as a database, a memory table and a file in a distributed manner. Regarding improvement.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a conventional resource access method. In this example, the server B manages the file F as a resource, and the server A functions as a client that issues an access request to the file F.

The name information of the server B which manages the file F is incorporated in the client application 1 of the server A in advance. When the server A accesses the file F, the client application 1 specifies the name of the server B and issues an access command for the file F (step S1). Then, the server application 2 of the designated server B accesses the file F in response to the access command (step S2,
S3), and returns the access result to the client application 1 (step S4).

[0004]

As described above, in the conventional resource access method, the resource is accessed by designating the name of the server that manages the resource desired to be accessed. Therefore, especially in a distributed resource management system, it is necessary to create a client application by incorporating the names of all the servers that manage resources. As a result, there is a problem that the work of creating the client application is troublesome and the productivity is poor.

When the resource location is dynamically changed to another server or a new resource is added, the system is stopped, the server name setting of the client application is changed, and the server is restarted. There must be.

In view of the above conventional problems, the present invention allows a client to access a desired resource in a distributed resource management system without being aware of the name of the server that manages the resource, and as a result, the client application It is an object of the present invention to provide a resource access method capable of improving productivity.

[0007]

A resource access method for a resource distribution management system according to the present invention comprises a resource name management means for managing the name of a server managing a resource in the system. Then, the client issues a resource access command to the server name acquisition means for acquiring the name of the server managing the resource to be accessed from the resource name management means and the server specified by the acquired server name. And access command means for issuing.

Further, a resource access method for a resource distribution management system according to the present invention includes a process of managing a name of a server managing the resource by a predetermined resource name server and a resource which the client intends to access. A process of providing the name of the managed server from the resource name server to the client, and a process of issuing an access command to access the resource desired by the client from the client to the server specified by the provided server name. Equipped with.

[0009]

According to the present invention, information as to which resource in the system is managed by which server is managed by the server name management means. When attempting to access an arbitrary resource, the client inquires of the server name managing means about the server name managing the resource desired to be accessed, obtains this, and issues an access command based on the server name. Therefore, the client can access any resource without owning the server name.

Also, change to a server that manages resources,
If a change such as addition or deletion occurs, it can be easily dealt with by only updating the management content of the server name management means. In this case, it is desirable that the server name management means be configured to update the management content in response to the server change.

In a preferred embodiment, each client has a cache table in which the server name obtained in the past from the resource name managing means is registered.
Then, the client first searches the server name of the access target from the cache table before accessing,
If the search fails, then the server name is acquired from the resource name management means. By using this cache table, the server name can be acquired at high speed.

Further, in a preferred embodiment, the client obtains the server name to be accessed by inquiring to the server name management means when the access made based on the server name retrieved from the cache table fails. ,
Try to access again. As a result, even when the server that manages the resources changes, it becomes possible to automatically specify the server name after the change and access.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a resource access system in a distributed resource management system according to the present invention.

In FIG. 1, in addition to a server A having a client application 11 that issues an access request for a resource and a server B having a server application 12 that manages a file F that is a resource,
A resource name server RN for managing the name of the server that manages the resources is provided. These servers A, B and RN are connected by a network so that they can communicate with each other.

Although not shown, in the present system, there are one or more other servers that manage files in the same manner as the server B, and the resources of the entire system are managed by the plurality of servers. It is divided into multiple files and distributed and managed. Further, similarly to the server A, there may be another server that issues a resource access request. Further, all the servers may have both the functions of the server A and the server B. Although the function of the resource name server RN can be shared by a plurality of servers, preferably only one server in the system should be responsible for this function.

The resource name server RN has a resource name table 14, and this resource name table 1
In 4, the names of all files in the system and the names of the servers that manage those files are stored in association with each other.

The resource name server RN uses the resource name table 14 by the name server process 13.
Manage. That is, the name server process 13 requests from a predetermined server or center (not shown) whenever there is a change, addition, or deletion of a server that manages a file (hereinafter referred to as a server name change). In response, the registered content of the resource name table 14 is rewritten to the content according to the change of the server name. When an inquiry about the server name that manages a specific file is input from an arbitrary server, the name server process 13 refers to the resource name table 14 to check the server name,
Answer the server that made the inquiry.

The client application 11 of the server A has a local cache table 15, and every time the server name of a specific file is inquired of the resource name server RN and the answer is received, the file name and the server name are associated with each other. Registered in the local cache table 15. Therefore, in the local cache table 15, a large number of sets of file names and server names that the client application 11 has inquired of the resource name server RN in the past are registered within the limit allowed by the capacity. On the other hand, the client application 11
The information of the server name that manages the resource is not incorporated in itself.

The client application 1
1 refers to a file to be accessed by first referring to the local cache table 15 when accessing an arbitrary file, and then by inquiring to the resource name server RN if the local cache table 15 is insufficient. Is configured to acquire information on the server name that manages the server and specify the server name to issue an access request.

In such a configuration, for example, the server B
When the client application 11 of the server A wants to access a file F managed by the client A, the client application 11 first refers to the local cache table 15 managed by itself and searches for the file name “file F” to be accessed ( Step S1
1) If the "file F" exists, the corresponding server name "server B" is read from the local cache table 15 (step S12). On the other hand, if the "file F" is not in the local cache table 15, the client application 11 next inquires of the resource name server RN about the server name managing the "file F" (step S13).

When the name server process 13 of the resource name server RN receives the above inquiry from the client application 11, the resource name table 14 is received.
With reference to, the server name “server B” corresponding to the file name “file F” identified by the inquiry is acquired (steps S4 to S5), and this server name “server B” is referred to as server A.
It returns to the client application 11 (step S16). Upon receiving the server name “server B” from the resource name server RN, the client application 11 registers the file name “file F” and the server name “server B” in the local cache table 15.

As described above, the client application 11 acquires the server name "server B" for managing the access target from the local cache table 15 or the resource name server RN. Then, the client application 11 next has the server name “server B”.
Is specified and an access command for the file F is issued to the network (S17).

Server B named by the access command
Then, the server application 12 receives the access command, accesses the designated file F (steps S18 and S19), and returns the access result (for example, the content after the access of the accessed record) to the client application 11. Yes (step S2
0).

As described above, the client application 11 makes an inquiry to the resource name server RN even if it does not hold the server name for managing the file by itself, or a cache table in which past inquiry results are registered. By referring to 15, it is possible to obtain the server name that manages an arbitrary file and access the file.

Also, when there is a change in the server name,
Since the resource name server RN updates the resource name table 14 substantially in real time, the client application 11 need not be aware of any changes in the server name.

FIG. 2 shows the flow of access processing when the server name changes. Hereinafter, after the management location of the file F is transferred from the server B to the server C,
The case where the client application 11 accesses the file F will be described as an example.

As described above, the client application 11 first retrieves "file F" from its local cache table 15. If there is a "file F" in the local cache table 15, the server name is the conventional "server B". In this case, the client application 11 issues an access request for the file F by designating the “server B”, but since a response “access failure” is returned from the server B, the client application 11 next sends the resource name server RN. It inquires the server name of "file F" (step S21). Also, when there is no "file F" in the local cache table 15, the client application 11 similarly inquires the resource name server RN about the server name of "file F" (step S21).

Then, the resource name server RN acquires the server name for managing the file F from the resource name table 14 (step S25). In this case, since the resource name table 14 has already been updated, “server C” is acquired as the server name that manages the file F. The resource name server RN returns this server name "server C" to the server A (step S2).
6).

The server A receives this server name "server C" (step S22), and this server name "server C"
Is specified to issue an access command to the file F (step S23).

The server C receives this access command (step S27), accesses the file F (step S28), and returns the access result to the file F to the server A (step S29). Then, the server A receives the access result (step S24) and finishes the access process to the file F.

As described above, the contents of the client application 11 need not be changed even if the server name changes. There is no need to change the contents of the name server process 13 and the server application 12, either.

[0032]

As described above, according to the present invention, in a distributed resource management system, a client can access an arbitrary resource without paying any attention to the name of the server that manages the resource.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a resource access system according to the present invention.

FIG. 2 is a flowchart showing an access process when a resource moves to another server in the embodiment.

FIG. 3 is a block diagram showing a conventional resource access method.

[Explanation of symbols]

 A, B, C server F file (resource) RN resource name server 11 client application 12 server application 13 name server process 14 resource name table 15 local cache table

Claims (5)

[Claims] 1. A resource access method for a client to access a resource distributedly managed by a plurality of servers, comprising resource name management means for managing the name of a server managing each distributed resource, The client wants to access the server name managing means for acquiring the name of the server managing the resource to be accessed from the resource name managing means, and the server specified by the acquired server name. A resource access method comprising: an access command means for issuing an access command to a resource. 2. The system according to claim 1, wherein said server name management means manages said server in response to the occurrence of the fact that a server name managing said resource has changed. A resource access method characterized by updating the name. 3. The system according to claim 1, wherein the server name acquisition unit has a cache table in which a server name already acquired by the resource name management unit is registered, and manages the resource to be accessed. The server name is searched for from the cache table, and if the search is unsuccessful, then the server name is acquired from the resource name management means and stored in the cache table. Registered, the access command means, based on the searched server name when the search from the cache table is successful, and the server name obtained from the resource name management means when the search fails. A resource access method, wherein the access command is issued based on the above. 4. The method according to claim 3, wherein when the access made based on the server name retrieved from the cache table fails, the server name acquisition means manages the resource to be accessed. A resource access system characterized in that the server name managing unit acquires the existing server name, and the access command unit reissues the access command based on the server name acquired from the resource name managing unit. 5. In a system in which a plurality of servers manage resources in a distributed manner, in a resource access method for a client to access a resource managed in a distributed manner, the name of the server that manages each distributed resource. In a predetermined resource name server, providing a name of a server that manages a resource that the client is trying to access from the resource name server to the client, and providing the client with the name. Issuing a command to access the resource desired to be accessed to the server specified by the specified server name.