JP3320221B2 - Client / server system and workstation for the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a client / server system in which a request from a client is processed by a multi-stage server, and a workstation device used as a client or a server in the system.

[0002]

2. Description of the Related Art In recent years, a plurality of workstation devices have been connected to a client /
2. Description of the Related Art A server system is configured, and a request from a client is processed by a multi-stage server. For example, FIG. 5 schematically shows an example in which a request from a client is processed by a two-stage server. In FIG. 5, 40
Denotes a client application program (hereinafter, referred to as a client application), and 41 denotes a first-stage server application program (hereinafter, referred to as a server application;
SV-A), 42 is a second-tier server application (SV-B)
It is. Although FIG. 5 shows only the application programs in the form of blocks, these programs are actually provided as software in the workstation device.

[0003]

By the way, in a client / server system in which a request from a client is processed by a multi-stage server, a request is made while the processing is performed normally through a plurality of stages of servers. There is a case where a request is made to the requesting server before processing is sequentially returned to the original server.

For example, as shown in FIG. 5, when processing is performed by a two-stage server, a processing request is issued from a client application 40 to a first-stage server application 41, and the first stage receiving the processing request receives the processing request. Server application 41
Issues a processing request to the second-stage server application 42, and then receives the processing request, the second-stage server application 42 issues a processing request to the server application 41 that has requested this processing request. Shall be done.

In such a case, a deadlock (deadlock;
It is difficult to avoid this situation in which resource usage competes and each other becomes a waiting state and cannot move. FIG. 5 shows the simplest two-stage server configuration. However, if the server configuration actually has a multi-stage configuration, deadlock is likely to occur. In some cases, the occurrence of this deadlock is first known during a system test, and it is difficult to determine the cause of the deadlock.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made to find out the cause of a deadlock in response to a client's request, and to take a measure corresponding to the cause. It is an object of the present invention to provide a client / server system and a workstation for the system, which can reliably avoid deadlock caused by issuing a multiple processing request to a processing request source.

[0007]

FIG. 1 is a block diagram showing the principle of the present invention. In FIG. 1, reference numeral 1 denotes a workstation device, and each workstation device 1 is communicably connected via a network 2. Client / server that processes requests from clients by a multi-stage server
It constitutes a server system.

Each workstation device 1 includes a tag adding unit 3, a tag determining unit 4, and an error processing unit 5.
Is provided. Although FIG. 1 shows only the configuration of one workstation device 1 in detail, the other workstation devices 1 have the same configuration.
Here, the tag adding unit 3 adds a tag unique to the request source to the processing request when making a processing request to the server (workstation device 1 of the request destination).

Further, upon receiving a processing request from the client, the tag determining unit 4 refers to the tag added to the processing request and determines whether or not the tag has a tag unique to its requester. Is what you do. Further, when the tag determination unit 4 determines that the tag added to the processing request includes a tag unique to the request source, the error processing unit 5 suspends the processing and sends the processing request to the request source (client ) To return the error.

[0010]

In the client / server system of the present invention and the workstation device for the system described above with reference to FIG. 1, the client (workstation device 1) makes a processing request to the server (requested workstation device 1). At this time, a tag unique to the request source is added to the processing request by the tag adding unit 3.

In the server which has received the processing request from the client, the tag determining unit 4 refers to the tag added to the processing request and determines whether or not the tag has a tag unique to its requester. You. When the tag determination unit 4 determines that the tag added to the processing request includes a tag unique to the requester, the error processing unit 5 suspends the processing, and the processing request is transmitted to the requester (client). ) Is returned to error.

That is, each time a processing request is made to the server, the tag adding unit 3 refers to the tags sequentially added to the processing request. Can be determined to have been issued before, and the processing has already been requested. Executing such a processing request causes a deadlock, as described above, so that the cause of the deadlock can be quickly found by referring to the tag.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a client / client as an embodiment of the present invention.
FIG. 3 is a block diagram showing a server system and a workstation device for the system. As shown in FIG.
Also in this embodiment, the three workstation devices 10, 2
0 and 30 are communicably connected to each other via a network 2 such as a LAN.

These workstation devices 10, 2
0 and 30, in the present embodiment, basically, the workstation device 10 functions as a client, the workstation devices 20 and 30 function as servers, and a client / server that processes requests from clients by a multi-stage server. A server system is configured. For this reason, the workstation device 10 is provided with a client application program (hereinafter, referred to as a client application) 11 for performing processing using a server, and the workstation devices 20 and 30 are adapted to handle processing requests, respectively. Server application programs (hereinafter, referred to as server applications) 21 and 31 for performing processing.

The workstation devices 10, 2
Command transmission mechanisms 12, 22 and 32 for transmitting a command for performing a processing request to the server are provided in 0 and 30, respectively, and the workstation devices 20 and 30 functioning as servers are provided with command as a processing request. Are respectively provided.

Then, the command transmitting mechanism 1 of the present embodiment
2, 22, and 32 include a tag generation unit 6, a tag addition unit 3, and a tag deletion unit 7, and the command receiving mechanisms 23 and 33 of the present embodiment include a tag determination unit 4 and an error processing unit 5. It is provided. Here, the tag generation unit 6 determines whether each of the workstation devices 10, 20, 30
For each, workstation ID, requesting process ID
Based on the processing macro ID of the requester and the requester, a self-requester-specific tag is generated.

The tag adding unit 3 includes a command transmitting mechanism 12,
When the processing request command is transmitted to the server (request destination workstation device) by the server 22, the request source unique tag generated by the tag generator 6 is added to the request table in the header part of the processing request command ( Stack). When the command receiving mechanisms 23 and 33 receive the processing request command from the client, the tag determination unit 4 refers to the tag in the request table in the header part of the processing request command, and the tag unique to its own request source tag is included in the tag. It is to determine whether or not it exists.

The error processing unit 5 interrupts the process when the tag determination unit 4 determines that the request source unique tag exists in the request table, and returns the processing request to the request source (client) as an error. It is to let. The tag deletion unit 7 normally executes and terminates the processing request command from the client, and returns the processing request to the request source normally. Is to be deleted.

Next, the operation of the present embodiment configured as described above will be described with reference to FIGS. First, FIGS. 3 and 4
According to the flowchart (steps S1 to S9) shown in FIG.
The operation of the command transmission mechanisms 12, 22, 32 and the command reception mechanism of the present embodiment will be described.

When each of the command transmission mechanisms 12, 22, 32 receives a processing request, the request is transmitted to the processing request (CAL).
L) or a return request after normal end of processing (RETURN) (Step S1 in FIG. 3), and a processing request request (CALL)
In the case of, the tag generation unit 6 uses its own request source unique tag based on the workstation ID, the process ID of the request source, and the processing macro ID of the request source for each of the workstation devices 10, 20, and 30. Is generated (step S2 in FIG. 3).

Then, the tag adding unit 3 sets the request source unique tag generated by the tag generation unit 6 in the request table in the header of the processing request command to be transmitted to the server (step in FIG. 3). S3), a processing request command is transmitted to the server to make a processing request (FIG. 3).
Step S4). On the other hand, each of the command receiving mechanisms 23 and 33 that has received the processing request command refers to the request table in the header part of the processing request command and determines whether the tag corresponding to itself exists by the tag determination unit 4. (Step S7 in FIG. 4). As a result of the determination, when the corresponding tag does not exist, a processing request is issued to the server application 21 or 31 of the own device (step S8 in FIG. 4). However, as a result of the determination in step S7, if the corresponding tag already exists, the error processing unit 5 interrupts the processing without requesting the processing to the server application 21 or 31, and returns an error to the request source. (Step S9 in FIG. 4).

When the processing shifts to step S8 in FIG. 4 and the processing in the server applications 21 and 31 ends normally,
A return request (RETURN) is issued to return to the request source normally, and control is transferred to the command transmission mechanisms 22 and 32. This allows
In the command transmission mechanisms 22 and 32, step S1 of FIG.
Then, the process proceeds to step S5, where the tag deletion unit 7 deletes the requester-specific tag of the self (the corresponding server application) from the request table in the header part, adds the updated contents of the request table, and (Step S6 in FIG. 3).

A more specific example of a processing request will be described with reference to FIG.
When the client application 11 makes a processing request to the server application 21 of the workstation device 20, the command transmitting mechanism 12 adds its own tag “CL” to the header portion H of the processing request command C1. A processing request command C1 is transmitted to the workstation device 20 to make a processing request.

In the workstation device 20, the command receiving mechanism 23 refers to the tag of the request source process to check whether it is issued to itself, and if appropriate, sends a process request to the server application 21. Further, when the server application 21 makes a processing request to the server application 31 of the workstation device 30, the command transmitting mechanism 22 adds its own tag "SV-A" to the header H of the processing request command C2. And the processing request command C
2 is transmitted to the workstation device 30 to request processing.

In the workstation device 30, the command receiving mechanism 33 refers to the tag of the request source process to check whether or not it has already been issued to itself.
If a processing request has not been made to itself, a processing request is made to the server application 31. Then, when the server application 31 ends the processing and returns to the request source,
The command transmission mechanism 32 checks whether or not a request has been made to another server. If the request has not been made to another server, the process returns to the request source. When the server application 21 ends the process and returns to the request source, the tag delete unit 7 of the command transmission mechanism 22 deletes the tag for the server application 21 and returns to the request source normally.

By the way, after the processing request is made from the client application 11 to the server application 21 and the server application 31 as described above, the server application 31
However, as shown in FIG. 2, when making a processing request to the server application 21 of the workstation device 20, the command transmission mechanism 32 adds its own tag “SV-B” to the header H of the processing request command C3. In addition, the processing request command C3 is transmitted to the workstation device 20 to make a processing request.

At this time, if the command receiving mechanism 23 of the workstation device 20 refers to the tag of the request source process to check whether or not it has already been issued to itself, the header portion H of the command C3 is checked. Has its own tag "SV-A" already set. Therefore, it is determined that the command C3 has already been issued to itself, and the error processing unit 5 interrupts the processing without requesting the processing and returns to the request source as an error.

Thus, according to one embodiment of the present invention,
Each time a processing request is made to the server, if the own request source unique tag exists by referring to the tags sequentially added to the header part of the processing request command, the processing request is issued by itself before It can be determined that the processing has already been requested. Executing such a processing request will cause a deadlock,
If your own request source tag exists in the header part,
By interrupting the processing and returning the error to the request source, the cause of the failure can be quickly found, and there is an advantage that the deadlock caused by the issuance of the multiple processing request to the processing request source can be reliably avoided.

In the above-described embodiment, the workstation device 10 basically functions as a client and does not receive a processing request unlike a server, and does not have a command receiving mechanism. The command receiving mechanism may be provided in the same manner as in the workstation devices 20 and 30 functioning as servers.

In the above-described embodiment, the client application and the server application exist on different workstations. However, the client application and the server application may exist in the same workstation. . Further, in the above-described embodiment, the case where the server is provided with two stages has been described. However, the present invention is not limited to this, and is similarly applied to the case of three or more stages, and more servers are provided. It functions more effectively when processing is performed using a server.

[0031]

As described above in detail, according to the client / server system and the workstation for the system of the present invention, each time a processing request is made to the server, the tag sequentially added to the processing request is added. By referring to the information, the cause of the deadlock occurrence can be quickly found.

When the cause of the deadlock is found, the process is interrupted and the error is returned to the request source, so that the cause of the failure can be quickly found, and the process can be performed to issue the multiple processing request to the process request source. This has the effect of reliably avoiding the deadlock caused.

[Brief description of the drawings]

FIG. 1 is a principle block diagram of the present invention.

FIG. 2 is a block diagram showing a client / server system and a workstation device for the system as one embodiment of the present invention.

FIG. 3 is a flowchart for explaining the operation of the command transmission mechanism of the embodiment.

FIG. 4 is a flowchart for explaining the operation of the command receiving mechanism of the embodiment.

FIG. 5 is a block diagram for explaining a general deadlock occurrence state.

[Description of Signs] 1 Workstation device 2 Network 3 Tag addition unit 4 Tag determination unit 5 Error processing unit 6 Tag generation unit 7 Tag deletion unit 10, 20, 30 Workstation device 11 Client application program 12, 22, 32 Command transmission Mechanism 21, 31 Server application program 23, 33 Command receiving mechanism

Claims (2)

(57) [Claims] 1. A client / server system in which a request from a client is processed by a multi-stage server, wherein a tag unique to the request source is added to the processing request when a processing request is made to the server. When the server receives a processing request from the client, the server refers to the tag added to the processing request and determines whether or not the tag has a tag unique to the requester of the server. A tag determining unit, and when the tag determining unit determines that the tag added to the processing request includes a tag unique to the requester,
A client / server system, comprising: an error processing unit that interrupts processing and returns the processing request to an error source of the processing request. 2. In a client / server system in which a request from a client is processed by a multi-stage server, a workstation device used as a client or a server. A tag adding unit for adding a tag to the processing request, and upon receiving the processing request, referencing the tag added to the processing request and determining whether or not the tag has a tag unique to its own request source. A tag determination unit to perform, and when the tag determination unit determines that the tag added to the processing request includes a tag unique to its own request source,
A workstation device for a client / server system, comprising an error processing unit for interrupting processing and returning the processing request to an error source of the processing request.