JP4742769B2 - Shared data access system - Google Patents

Description

  The present invention relates to a shared data access system in which a plurality of client nodes access shared data of a server node.

  The production system takes the form of a shared data access system in which a plurality of client nodes in charge of each process access shared data of a server node that provides a data sharing service.

  FIG. 3 is a functional block diagram showing a configuration example of a conventional shared data access system. Reference numerals 1 and 2 denote two of a plurality of client nodes. Reference numerals 11 and 21 denote applications that run on these client nodes. Reference numeral 3 denotes a communication bus to which these client nodes are connected.

  Reference numerals 4, 5, and 6 denote three of a plurality of server nodes that provide a data sharing service. These server nodes are connected to the communication bus 3 and provide data held by the client nodes upon access from the client nodes.

  Reference numeral 41 denotes a database provided in the server node 4, and DATA1 is shared data held therein. The client nodes 1 and 2 access the server node 4, and the applications 11 and 21 acquire the shared data DATA1 and execute a predetermined process.

  NT1 is a data transfer time between the application 11 and the server node 4. NT2 is a data transfer time between the application 21 and the server node 4. NT3 is the data transfer time between applications when the application 11 requests the application 21 for processing. These transfer times vary due to network delays and the like.

The system of FIG. 3 operates as follows.
(1) Application 11 and application 21 share and reference DATA1.
(2) The value of DATA1 changes from V1 to V2 at a certain time.
(3) After NT1, the value of the application 11 changes from V1 to V2.
(4) The application 11 issues a request to the application 21 to perform processing using the value of DATA1.
(5) After NT2, the value of the application 21 changes from V1 to V2.
(6) After (NT1 + NT3), the application 21 receives the request in (4) and executes a certain process using the value V2 of DATA 1.

  Patent Document 1 describes an information processing apparatus in which a shared memory can be accessed from a plurality of bus masters.

JP-A-6-259315

  In the above operation, when (NT1 + NT3) <NT2, the execution order of (5) and (6) is reversed, and this system operates in the order of (6) → (5). In this case, at the time (6), the value of DATA1 that the application 21 still has is V1, and the application 21 uses V1. As a result, there is a problem that this system cannot operate as expected.

  The present invention has been made to solve the above-described problems, and aims to realize a shared data access system in which a system sharing data does not cause a malfunction due to a difference in data transfer time due to a network delay or the like. Yes.

In order to achieve such a subject, the present invention has the following configuration.
(1) In a shared data access system in which a plurality of client nodes access shared data of a server node via a communication interface ,
The specific server node that can be transferred in a time shorter than the longest transfer time in the data transfer time between the application in the plurality of client nodes and the server node , the transfer held in the communication interface of the plurality of client nodes Specific server node search means for acquiring time information and searching;
Shared data moving means for moving the shared data to the searched specific server node; access destination changing means for changing the access destination of the plurality of client nodes to the specific server node;
A transfer time adjusting means for adjusting a transfer time between the plurality of client nodes and the server node by a delay means provided in the communication interface of the plurality of client nodes ;
A shared data access system comprising:

(2) The shared data according to (1), wherein the transfer time adjusting unit adjusts transfer times of the plurality of client nodes based on a difference between each transfer time and the longest transfer time. Access system.

(3) The shared data access system according to (1), wherein the specific server node search unit measures a transfer time between the plurality of client nodes and the specific server node by performing statistical processing.

As is apparent from the above description, the present invention has the following effects.
(1) The equivalence of shared data referred to by a plurality of applications is guaranteed at a certain time.

(2) Since equivalence is guaranteed, malfunction of processing depending on this can be avoided.

(3) Since equivalence is guaranteed, there is no need to be aware of this in the application, and the system design becomes easy.

  The present invention will be described in detail below with reference to the drawings. FIG. 1 is a functional block diagram showing an embodiment of a shared data access system to which the present invention is applied. The same elements as those of the conventional system described with reference to FIG. Hereinafter, the characteristic part of the present invention will be described.

  In FIG. 1, reference numeral 100 denotes a management apparatus that forms a feature of the present invention, and is connected to a communication bus 3 to communicate with a plurality of client nodes and a plurality of server nodes. In the management apparatus 100, 101 is a specific server node search means, 102 is a control means, 103 is a shared data moving means, 104 is an access destination changing means, and 105 is a transfer time adjusting means.

  The transfer time between application 11 and server node 4 is NT1, the transfer time between application 21 and server node 4 is NT2, the transfer time between application 11 and server node 5 is NT1 ', and the transfer time between application 21 and server node 5 is NT2'. , NT1> NT2 and NT1 ′> NT2 ′.

  The application 11 refers to the shared data of the server node 4 and simultaneously records the transfer time NT1. The recorded information is held as a1 in the communication interface 12. Similarly, the application 21 refers to the shared data of the server node 4 and simultaneously records the transfer time NT2. The recorded information is held as a2 in the communication interface 22.

  The specific server node search unit 101 acquires the record information a1 and a2 of the communication interfaces 12 and 22 of the client node, and searches for a server node that can be transferred in a time shorter than the longest transfer time in the client node. When the server node 5 is searched as a server node that satisfies the conditions in this search, this is set as a specific server node.

  Information on the retrieved specific server node is passed to the control means 102. The control unit 102 controls the shared data moving unit 103 based on the specific server information to output the commands b1 and b2 to the server nodes 4 and 5, and the shared data DATA1 held in the database 41 of the server node 4 is stored. To the database 51 of the server node 5.

  At the same time, the control unit 102 controls the access destination changing unit 104 to output the commands c1 and c2 to the communication interfaces 12 and 22 of the client nodes 1 and 2, and the access destination of these client nodes is changed from the initially set server node 4. The specific server node 5 is automatically changed. The user is not aware of this automatic change.

  At the same time, the control unit 102 controls the transfer time adjusting unit 104 to output the commands d1 and d2 to the communication interfaces of the client nodes 1 and 2, and the transfer times between the plurality of client nodes of the client nodes and the server node. Is adjusted based on the difference between each transfer time and the longest transfer time.

  Specifically, the adjustment time (NT2′-NT1 ′) is added to the transfer time NT1 ′ between the application 11 and the specific server node 5, and the data transfer time between the application 11 and the application 21 and the specific server node 5 is Both are made equal to NT2 '. The transfer time is adjusted (delayed) by delay means provided in the communication interface.

  FIG. 2 is a transition diagram illustrating a change in access state according to a series of sequences executed by the management apparatus 100. When the specific server node 5 is searched, the shared data DATA1 held in the server node 4 is moved to the specific server node 5. At the same time, the access destinations of the applications 11 and 21 are changed to the specific server node 5. Furthermore, the transfer time between the application 11 and the specific server node 5 is adjusted from NT1 ′ to NT2 ′.

  Such a change sequence is automatically executed by the management apparatus 100 by monitoring the transfer time of the system in real time, and the equivalence of the shared data referred to by the application is guaranteed. The user can continue to operate the system without being aware of this.

  The transfer time between each client node and server node changes dynamically depending on the network conditions. Therefore, the accuracy of the specific server node search can be improved by measuring the transfer time by statistical processing (in the simplest case, average processing).

  Furthermore, by measuring the transfer time reflecting the throughput of shared resource processing between each client and server node, the movement of shared resources is not concentrated in one place, improving the accuracy of moving to the optimal specific server. Can be made.

It is a functional block diagram which shows one Embodiment of the shared data access system to which this invention is applied. It is a transition diagram which shows the change of the access state by the series of sequences performed by the management apparatus. It is a functional block diagram which shows the example of a conventional shared data access system structure.

Explanation of symbols

1, 2 Client node 11, 21 Application 12, 22 Communication I / F
3 Communication bus 4 Server node 5 Specific server node 41, 51 Database 42, 52 Communication I / F
DESCRIPTION OF SYMBOLS 100 Management apparatus 101 Specific server node search means 102 Control means 103 Shared data movement means 104 Access destination change means 105 Transfer time adjustment means

Claims (3)

In a shared data access system in which a plurality of client nodes access shared data of a server node via a communication interface ,
The specific server node that can be transferred in a time shorter than the longest transfer time in the data transfer time between the application in the plurality of client nodes and the server node , the transfer held in the communication interface of the plurality of client nodes Specific server node search means for acquiring time information and searching;
Shared data moving means for moving the shared data to the searched specific server node; access destination changing means for changing the access destination of the plurality of client nodes to the specific server node;
A transfer time adjusting means for adjusting a transfer time between the plurality of client nodes and the server node by a delay means provided in the communication interface of the plurality of client nodes ;
A shared data access system comprising: 2. The shared data access system according to claim 1, wherein the transfer time adjusting unit adjusts transfer times of the plurality of client nodes based on a difference between each transfer time and the longest transfer time. 2. The shared data access system according to claim 1, wherein the specific server node search means measures the transfer time between the plurality of client nodes and the specific server node by performing statistical processing.

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