JP3513550B2 - Transaction continuation method and resource manager therefor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transaction continuation method, and in particular, a client requests each server to perform processing based on a transaction, and the server that receives the request re-requests the resource access in the server to the resource manager. After the transaction is completed, the client notifies the transaction management unit of the transaction commit, and the transaction management unit which receives the transaction commits the two-phase commit process to the resource manager.

There are various relationships between a server and a resource manager, such as a one-to-one correspondence between them and a case where one resource manager is requested to access each resource by a plurality of servers.

Further, the resource manager in the two-phase commit processing performs the actual update of the processing result associated with the resource access and the reply as to whether the resource access has been rolled back or not on a server-by-server basis.

Generally, the form of a computer system is
There is a shift from a centralized type in which programs are arranged on a host to a client / server type in which programs for each function are arranged in each of a personal computer, a server, and a host, and these are combined to perform business.

In the client / server type computer system, a client that accepts one transaction (processing request) responds to the transaction by calling a plurality of servers prepared in advance for each function and requesting the processing. ing. An example of a processing mode using a plurality of servers is that one server executes a DBMS (Database Management System) and another server executes asynchronous communication.

Conventionally, when an error occurs in a server or a resource manager that executes the resource access,
Regarding the resource access of another server that has already been normally executed, its state is guaranteed, and it is requested that the processing of the next server be continued. The present invention responds to such a request. It is a thing.

[0007]

2. Description of the Related Art FIG. 6 is an explanatory view showing an outline of a conventional global transaction, 1 is a client, 2 is
Is a transaction manager, 3 and 3'are servers, 4
Is a resource manager, 5 is an XA interface processing unit, and 6 is a two-phase commit process.

Generally, in a client / server type computer system, a technique for ensuring consistency between resource access in server units executed by the resource manager 4 in response to requests from a plurality of servers 3, 3 '... There is a global transaction.

The global transaction is controlled by the software product of the transaction management unit 2, and the interface standard between the software products is standardized as the X / OPEN XA interface.

Here, the transaction management unit 2 starts a global transaction by a transaction start notification from the client 1, and then executes a two-phase commit process by a transaction commit notification from the client 1. Note that this transaction commit is issued when the processing of all servers based on the transaction ends normally.

Further, the servers 3 and 3'called from the client 1 re-request the resource manager in the processing procedure to the resource manager 4 by calling a function, for example. Then, when this series of processing ends normally, the server returns to the client 1 normally, and when an error occurs in this series of processing, the server returns to the client 1 abnormally. When an abnormality occurs in the resource manager 4, the abnormality return to the client 1 is performed via the requesting server.

If an abnormality occurs, the corresponding resource access is rolled back by the resource manager 4. When an error occurs in the server 3, 3 ', the server requests the resource manager 4 to roll back the corresponding resource access. However, this rollback request is effective when an error occurs in the processing after returning from the source manager 4 to the server.

The client 1 notifies a transaction rollback to the transaction management unit 2 in response to an abnormal return from a certain server, and the transaction management unit 2 receiving this notification rolls back the resource access of the entire global transaction, and then Based on the instruction to start the transaction again, the processing shifts to the retry processing routine or the proxy processing routine.

In the case shown in the figure, the resource access of the server 3 which has returned to the normal state is also rolled back by the rollback instruction of the transaction management unit 2 accompanying the abnormal return of the server 3 '.

On the other hand, when all the servers have returned to normal, the client 1 commits the transaction by the XA interface processing unit 5 of the transaction management unit 2.
To the two-phase commit process 6.

That is, the XA interface processing unit 5 notifies the resource manager 4 of the commit, and the resource manager 4 receiving this notification actually updates the content of resource access of each server, and further rolls back each server. By referring to the resource access management information regarding presence / absence, "normal" is returned for a server for which resource access is not rolled back, and "abnormal" is returned for a server for which resource access is rolled back.

Note that this resource access management information is created and stored in the resource manager 4. For example, if the normal recovery of all the servers is true, the reply to the XA interface processing unit 5 of the two-phase commit is "normal". Will only be.

[0018]

As described above, according to the conventional transaction management method, when an error occurs in the processing of the server called by the client or the corresponding resource access, the global including the normally executed resource access is executed. Since the retry process or the proxy process is executed after the entire transaction is rolled back, there is a problem that the efficiency of the data process is deteriorated.

Further, in order to deal with various abnormalities, the client program must be designed in consideration of a processing sequence such as a transaction being stopped depending on the degree of the abnormality, and the productivity of program development is poor. There were problems such as.

Therefore, in the present invention, by rolling back only the resource access corresponding to the server in the abnormal state and executing the retry processing or the proxy processing in units of this server,
The purpose is to improve the efficiency of data processing and improve the productivity of program development.

Further, when executing this rollback, a standard interface (XA interface processing section 5) is used.
It is an object of the present invention to enable the rollback to be executed by the resource manager by itself without changing, that is, without depending on the transaction management program.

[0022]

FIG. 1 is a diagram for explaining the principle of the present invention, and is a diagram for comparison with the conventional case of FIG. 6, but the mode of abnormality occurrence in each server is shown in FIG. The opposite relationship, that is, the server 3 is abnormally recovered and the server 3'is normally recovered.

As components not shown in FIG. 6, the server program 7 and the invalidation API (Application I
nterface) 8, a processing unit 9 for executing rollback of resource access, and a processing unit 10 for executing omission of correspondence to two-phase commit.

Here, the main difference from the conventional case of FIG. 6 is that when an abnormality occurs in the process of the server 3, the invalidation instruction is issued from the server to the resource manager 4 to issue this invalidation instruction. The resource manager 4 received via the invalidation API 8 rolls back the corresponding resource access in the processing unit 9 and executes the omission (described later) of the two-phase commit process regarding the server 3 in the processing unit 10. Resource manager 4 When an error occurs in the resource access corresponding to the server 3, the processing unit 9 rolls back this resource access, and the processing unit 10 executes the omission of the two-phase commit processing related to the server 3 (described later). When an abnormal return from the server occurs, the client 1 executes a transfer routine to the proxy server at an arbitrary point after that. This and transaction management section 2, when the "abnormality" is notified as a response of the two-phase commit (see FIGS. 4 and 5) or the like to instruct the rollback of the entire global transaction to.

The omission of the two-phase commit processing 6 for the server 3 means that the server 3 notifies the XA interface processing unit 5 that the server 3 is not subject to the two-phase commit processing 6 (see FIG. 4) The resource manager 4 notifies the server 3 to the two-phase commit of "normal" as in the case where the resource access is normally executed (see FIG. 5).

In the former case, 2 between the XA interface processing unit 5 and the resource manager 4 relating to the server 3
Processing time is reduced by the time of phase commit,
In the latter case, the resource manager 4 notifies "normal" while the original commit process for the server 3 is not performed, that is, the resource access cannot be actually updated.

[0027]

According to the present invention, when an error occurs in the process in the server called by the client or the process in the resource manager requested to access the resource by the server, the resource manager independently executes the resource access. Is rolled back to return to the client abnormally, and "abnormal" is not returned in the subsequent two-phase commit processing from the transaction management unit for the server.

Further, rollback of the entire global transaction is executed when "abnormal" is notified as a reply of the two-phase commit process, and this rollback is also executed by abnormal return to the client. Absent.

Incidentally, the corresponding portion of the resource access management information held by the resource manager is deleted due to the rollback of the resource access executed when an abnormality occurs in the server or the resource manager (see FIG. 2). .

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 3 shows DB processing and OLTP (On Line Transac).
11) is an explanatory diagram showing an application example to a global transaction including a message guarantee type asynchronous message communication between applications in the field
Is a workstation, 12 is a client, 13 is a DB processing server, 14 is a writing server, 15 is a proxy server,
16 is a resource manager corresponding to the DB processing server, 17
Is a resource manager corresponding to a writing server, 18 is a printer, 19 is a file device for asynchronous message communication, and 20 is a large computer.

Here, the client 12 calls the DB processing server 13 and the writing server 14, and in the former case, the resource manager 16 adds or updates the database.
It executes processing such as deletion, and in the latter case, the file device 19 for asynchronous message communication by the resource manager 17
The process of writing a message to is being executed.

When an error occurs in the asynchronous message communication processing as shown in the figure, only the resource access here is rolled back, and the writing server 14 returns to the client 12 abnormally.

The client 12 receiving this is a proxy server
By calling 15 and running this, the printer
An abnormal message, that is, a message indicating that an error has occurred in the process of asynchronous message communication, is delivered to 18.

FIG. 4 and FIG. 5 are explanatory diagrams showing a state of the two-phase commit processing. RM (1) has a function of omitting the two-phase commit processing and has its own resource due to the occurrence of an abnormality. The resource manager / RM (2) that executed the rollback of the access has no abnormality in the request source server and its own processing. The resource manager / RM (3) has the function of omitting the two-phase commit processing. If not, and the resource manager that performed the rollback of its own resource access due to the occurrence of an error, shows the tables that respectively store the RM names and the necessity of the two-phase commit for each, respectively. There is.

Note that this RM name corresponds to the server that requested the resource access in a one-to-one correspondence, and the table 21 essentially describes whether or not two-phase commit is required for each server. There is.

Here, in the case of FIG. 4, the RM (1) having the function of omitting the two-phase commit processing and rolling back its own resource access is the target of the two-phase commit processing for the corresponding server. Notifying the XA interface processing unit 5 in advance of the fact that it is outside is the same, and in the case of FIG. 5, the same content as RM (2) in which no abnormality has occurred is the reply of the two-phase commit processing. Therefore, in any case, "abnormal" is returned as the response of the two-phase commit.
There is no notification from the RM (1) to the XA interface processing unit 5.

On the other hand, from the RM (3) which is in the state where the resource access is rolled back like this RM (1), FIG.
In any of the cases of FIG. 5 and FIG. 5, the XA interface processing unit 5 is notified of "abnormal" as a reply of the two-phase commit, and the transaction management unit 2 receiving this notification instructs the rollback of the resource access of the entire global transaction.

[0038]

As described above, according to the present invention, since only the resource access corresponding to the server and the resource manager in the abnormal state is rolled back and the retry process or the proxy process is executed for each server, -It is possible to improve the efficiency of data processing and improve the productivity of program development.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram showing a part of the processing by the resource manager when an abnormality occurs according to the present invention.

FIG. 3 is an explanatory diagram showing an example of application of the present invention to a global transaction including DB processing and message guarantee type asynchronous message communication.

FIG. 4 is an explanatory diagram showing the state of two-phase commit processing according to the present invention (No. 1).

FIG. 5 is an explanatory diagram showing a state of a two-phase commit process of the present invention (No. 2).

FIG. 6 is an explanatory diagram showing an outline of a conventional global transaction.

[Description of Reference Signs] In FIG. 1, 1 ... Client 2 ... Transaction management unit 3 ... Server 4 ... Resource manager 5 ... XA interface processing unit 6 ... Two-phase commit processing 7 ... ..Server program 8 ... Invalidation API 9 ... Processing unit for rollback of resource access 10 ... Processing unit for omission of support for two-phase commit

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-229333 (JP, A) JP-A-3-12773 (JP, A) JP-A-4-64146 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G06F 12/00 G06F 11/14 G06F 15/16-15/177

Claims (4)

(57) [Claims] 1. A client requests a process based on a transaction from each server, and the server which receives the request re-requests the resource manager for the resource access therein, and after the transaction ends, the client manages the transaction. In the transaction continuation method, the transaction management unit, which notifies the section of the transaction commit, executes the two-phase commit process for each of the servers with respect to the resource manager. The server abnormally returns to the client and issues an invalidation instruction to the resource manager. Upon receipt of the invalidation instruction, the resource manager executes rollback only for resource access corresponding to the issuing server. The above During the phase commit processing, the issuer server is excluded from the target of the two-phase commit processing. Therefore, “normal” is returned to the transaction management unit without performing the original processing relating to the issuer server. Transaction continuation method characterized by. 2. A client requests a process based on a transaction from each server, and upon receipt of this request, the server re-requests resource access from the server to the resource manager, and after the transaction ends, the client manages the transaction. In the transaction continuation method, the transaction manager that notifies the department of the transaction commit and executes the two-phase commit process for each server to the resource manager responds to any server. When an error occurs in the resource access of the resource manager, the resource manager executes an abnormal recovery to the server and rolls back only the resource access.
A transaction continuation method characterized by returning "normal" to the transaction management unit without performing the original process for the server in order to exclude it from the phase commit process. 3. The transaction management unit is configured to
3. The transaction continuation method according to claim 1, further comprising the step of instructing rollback of the entire global transaction when "abnormal" is received as a response to the phase commit process. 4. A client requests each server to perform processing based on a transaction, and the server which receives the request re-requests the resource manager for the resource access therein, and after the transaction ends, the client manages the transaction. The transaction management unit which has notified the unit of the transaction commit, and the transaction management unit which has received the notification, in the resource manager used for the transaction process of the type for executing the two-phase commit process for each server to the resource manager, When an error occurs in the resource access corresponding to the server, abnormal return to the server and rollback of only the resource access are executed, and when the two-phase commit processing is performed, the server is committed to the two-phase commit. place A resource manager, which returns "normal" to the transaction management unit without performing the original process for the server in order to exclude it from the reason.