JPH06161862A - Transaction controller - Google Patents

Abstract

PURPOSE:To simplify the interface of an application program. CONSTITUTION:When an application program A2 utilizes a transaction monitor A4 while executing a transaction at a computer A1, it is stored in a storage means A41 by the relevant transaction monitor A4. When ending the transaction by the application program A2, the end request of the transaction is outputted to a data base management system A3. Then, it is inquired from a state managing part A30 to the transaction monitor A4 whether the transaction monitor is utilized by the application program A2 or not. The update processing of a data base A5 of the computer A1 is performed by a retrieval/update control part A32. Then, the update processing is performed while synchronizing respective data bases A5 and B5 of plural computers A1 and B1 through the transaction monitor A4 with the transaction control part A31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a transaction for updating a database provided in a plurality of computers.
The present invention relates to a transaction control device capable of committing or rolling back as in the case of updating a database provided in one computer.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing the configuration of a conventional transaction control system. The system shown in the figure is connected by a communication control device via a communication line.
It consists of two computers A1 and B1. Computers A1 and B1
It has databases A5 and B5, respectively. Each of these databases A5 and B5 is composed of a magnetic disk device or the like, and is managed by database management systems A3 and B3. The respective computers A1 and B1 execute the application programs A2 and B2, respectively. These application programs A2 and B2 are users of the databases A5 and B5. First, the operation when the application program A2 uses only the database A5 of its own computer A1 will be described.

The application program A2 carries out a series of operations having a single meaningful meaning, such as withdrawal processing in banking business. In this case, the database management system A3 accesses the database A5 based on the access request from the application program A2 to the database A5. After a series of data update processing, the access to the database A5 is completed based on the release request from the application program A2. In this way, the processing operation from the access request of the database A5 to the completion of a series of accesses is called a transaction. Such a transaction is logically meaningless in the middle of the process, that is, in a state where some data in the database A5 is updated and some other data is not updated. Therefore, one transaction does not show an intermediate state with respect to another transaction, and the contents of the database are matched. That is, even if a failure such as power failure occurs during the operation of the system, the transaction does not start from an intermediate state when the operation of the system is resumed. In this way, the property that the states in the middle of a transaction cannot be seen between transactions is called transaction atomicity.

The atomicity of such a transaction is
Guaranteed by commitment control by the database management system. That is, while the application program A2 is executing a transaction, the database management system A3 saves the update result only in the temporary storage area and does not update the database A5 regarding a plurality of update processes that are sequentially executed. Then, at the end of the transaction, the application program A2 issues a commit to the database management system A3, whereby the database management system A3 makes a series of updates of the database A5 at a time for the first time. On the other hand, if the transaction is interrupted midway, the application program A2 issues a rollback to the database management system A3, thereby canceling the update result stored in the temporary storage area of the database management system A3. In this way, the database A5 is always updated in a logically meaningful manner from the viewpoint of other transactions.

[0005] The concrete method of writing the commit statement and the rollback statement in the application program A2 is "JIS X
3005 ", page 7. On the other hand, there are cases where one application is processed by the application programs A2 and B2 on a plurality of computers A1 and B1. For example, when performing a transfer business from one store to another in banking business, in FIG. 2, the application program A2 of the computer A1 updates the database A5 by a withdrawal process, and the application program B2 of the computer B1 executes the database. For B5, the update process by the deposit process is performed. In this case, the updating processes of the databases A5 and B5 performed by the application programs A2 and B2 are both related to one transfer operation, and these processes are included in one transaction. In order to impart the above-mentioned atomicity to such a transaction, the update processing of the databases A5 and B5 must be performed in synchronization.

Therefore, the application program A2 which performs a series of processing from the start to the end of the transaction performs the following operations. First, a transaction start request is issued to the transaction monitor A4. Then, it issues a search / update request for the databases A5 and B5 to the database management system A3. After the series of processing is completed, a transaction termination request is issued to the transaction monitor A4. When the transaction monitor A4 receives the transaction end request, the transaction monitor A4 and the transaction monitor B4 synchronize the update processing of the databases A5 and B5 managed by the database management systems A3 and B3.

FIG. 3 is an explanatory diagram of a processing procedure of conventional two-phase commit control. First, transaction monitor A4
After receiving the termination request from the application program A2 (time point T1), notifies the database management system A3 and the transaction monitor B4 of the transaction termination preparation (time points T2 and T3). Transaction monitor B4
Notifies the database management system B3 of this transaction end preparation (time point T4). Thus, the database management system B3 starts preparation for the transaction end, and when the preparation is completed, it responds to the transaction monitor B4 (time T5). The transaction monitor B4 sends this to the transaction monitor A.
4 (time point T6). On the other hand, when the database management system A3 also completes the preparations for transaction end,
This is notified to the transaction monitor A4 (time point T7). As described above, the transaction monitor A4 indicates that the preparation of the database management systems A3 and B3 is completed.
Confirmed by.

Thereafter, the transaction monitor A4
Transaction management is completed by database management system A3
And transaction monitor B4 (at time T
8, T9). The transaction monitor B4 notifies the database management system B3 of this (time point T1).
0). When the database management system B3 performs the update process and the transaction end is completed, the database management system B3 sends a response to that effect to the transaction monitor B4 (time T11). The transaction monitor B4 responds to the transaction monitor A4 (time point T12). On the other hand, when the transaction monitor A3 also performs the update process and the transaction end is completed, the transaction monitor A4 is notified of this (time T13). In this way, the updating of the databases A5 and B5 is surely completed. Finally,
The update completion is notified to the application program A2 (time point T1.
4). The atomicity of the transaction is guaranteed by the two-phase commit control as described above.

[0009]

However, the above-mentioned conventional technique has the following problems. That is, in FIG. 2, the commit or rollback in the transaction processing by the application program A2 is issued to the database management system in the case of a transaction that can be performed only by the computer A1. On the other hand, computers A1 and B
In the case of a transaction performed by both 1), it is sent to the transaction monitor A4. In other words, the transaction termination interface is performed depending on the content of the transaction. As a result, when writing a commit statement or a rollback statement in the application program A2, different programming had to be performed depending on the contents of the transaction. Therefore, there is a problem in that the programmer is confused and a program error is likely to occur. The present invention has been made by paying attention to the above points.
It is an object of the present invention to provide a transaction control device that does not need to be distinguished in an application program regardless of whether one job is processed by one database management system or a plurality of database management systems.

[0010]

A transaction control device of the present invention is a transaction control device for controlling a series of processes from the start to the end of a transaction involving an update process of each database provided in each of a plurality of computers. A storage unit provided in the transaction monitor for synchronizing the update processes, and storing the effect when the application program executing the transaction uses the transaction monitor,
A database management system that receives a transaction end request from the application program when the application program ends the transaction;
A status management unit that is provided in the database management system and inquires of the transaction monitor whether or not the application program has been used when a transaction end request is received from the application program, and an inquiry of the status management unit. As a result, when the transaction is not used by the application program, a search / update control unit for updating the database in the own computer and a result of an inquiry from the state management unit,
When the transaction is used by the application program, the transaction monitor comprises a transaction control unit for updating the databases of the plurality of computers while synchronizing the databases of the computers. Is.

[0011]

In the transaction control device of the present invention, when the transaction consisting of the update processing of each database provided in each of the plurality of computers is terminated, the transaction monitor is synchronized with the transaction monitor to synchronize the update processing with the transaction. If the application program that executes the transaction uses the transaction monitor, the fact is stored. Then, when the application program ends the transaction, it issues a transaction end request to the database management system in the local computer in which the application program is executed. Then, the database management system inquires of the transaction monitor whether or not the application program has been used, and when the application program is not used, the database in the local computer is updated. On the other hand, when the application program is used, the transaction monitor updates the database while synchronizing the databases of the plurality of computers.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the transaction control device of the present invention. FIG. 4 is a block diagram showing a hardware configuration example of the transaction control device of the present invention. In the example of FIG. 4, the computers A1 and B1 are the transaction control devices of the present invention. The computers A1 and B1 are composed of processors 11 and 21, main storage devices 12 and 22, magnetic disk devices 13 and 23, and communication control devices 14 and 24, respectively. The processors 11 and 21 sequentially read out and execute various programs stored in the main storage devices 12 and 22,
Perform data processing. The main storage devices 12 and 22 are transaction monitors A4 and B4, application programs A2 and B, respectively.
2. Stores programs for the database management systems A3 and B3. The magnetic disk devices 13 and 23 store various databases A5 and B5. The communication control devices 14 and 24 perform control for communicating with other computers B1 and A1 based on the instructions from the processors 11 and 21. In the examples of FIGS. 4 and 1, computers A1 and B1 are connected by a communication line, and a distributed database processing system including the databases A5 and B5 is configured.

In FIG. 1, each of the computers A1 and B1 is
It controls a series of processes from the start to the end of a transaction involving the update process of the other databases B5 and A5. Hereinafter, description will be made focusing only on the computer A1. The application program A2 executes various business processes. Each business process is executed as a transaction as described above. The database management system A3 is
The search and update of the database A5 of the own computer A1 are controlled, and the transaction monitor A4 synchronizes with the update process of the database B5 of the other computer B1. The transaction monitor A4 is provided with a storage unit A41 for storing the fact that the application program A2 uses the transaction monitor A4 when executing the transaction.

Further, the database management system A3 is
When the application program A2 ends the transaction, it receives a request for ending the transaction from the application program A2. Therefore, a state management unit A30 is provided in the database management system A3. When receiving the transaction end request from the application program A2, the state management unit A30 inquires of the transaction monitor A4 whether or not the application program A2 has been used. In response to the inquiry from the state management unit A30, the transaction monitor A4 searches the storage content in the storage unit A41. The state management unit A
As a result of the inquiry of 30, when the transaction by the application program A2 is not used, the application program A
It can be seen that the transaction No. 2 being executed is an update process for only the database A5 of the own computer A1 without communication with another computer B1. Therefore, at this time, only the search / update control unit A32 is activated.

The search / update control unit A32 uses the own computer A1.
The database A5 is searched and updated. On the other hand, as a result of the inquiry from the state management unit A30, when the transaction A4 is used by the application program A2, the transaction being executed by the application program A2 involves communication with another computer B1, and the update processing of the database B5 is performed. It turns out that this is also something to do. Therefore, at this time, the transaction control unit A31 is also activated in addition to the search / update control unit A32. The transaction control unit A31 includes a plurality of computers A1 and B1 by the transaction monitor A4 and the search / update control unit A32.
The databases A5 and B5 are updated in synchronization with each other. That is, the two-phase commit control described above is performed.

Next, the operation of the above-mentioned apparatus at the end of the transaction will be described. When the application program A2 finishes one transaction, it issues a commit or rollback request to the database management system A3. As a result, the state management unit A30 in the database management system A3 is activated.

FIG. 5 is a flow chart for explaining the processing procedure in the status management unit. First, application program A
When a transaction commit or rollback processing request is received from step 2 (step S1), the transaction monitor A4 is inquired whether the application program A2 uses the transaction monitor A4 (step S2). If the transaction monitor A4 is not used (step S3), the transaction control unit A performs transaction commit or rollback processing.
31 is requested (step S4). On the other hand, when the transaction monitor A4 is used (step S3),
It requests the transaction monitor A4 to perform commit or rollback processing (step S5).
The transaction monitor A4 requested to commit or roll back the transaction by the database management system A3 considers that the request is received from the application program A2. Therefore, transaction monitor A
Upon receipt of the transaction end request, the database 4 synchronizes with the transaction monitor B4 the update processing of the databases A5 and B5 managed by the database management systems A3 and B3.

FIG. 6 is an explanatory diagram of a processing procedure of two-phase commit control according to the present invention. First, the database management system A3, after receiving an end request from the application program A2 (time point T21), makes an inquiry to the transaction monitor A4 according to the flowchart of FIG. 5 (time point T2).
2, T23). The database management system A3 sends an end request to the transaction monitor A4 only when it is determined as a result of this inquiry that the database of the other computer B1 is updated (time T24). In response to the termination request from the database management system A3, the transaction monitor A4 prepares for the transaction termination, and the database management system A3 and the transaction monitor B4.
And (at time points T25 and T26). The transaction monitor B4 notifies the database management system B3 of this transaction end preparation (time point T27).
Thus, the database management system B3 starts preparation for the transaction end, and when the preparation is completed, it responds to the transaction monitor B4 (time point T2).
8). The transaction monitor B4 responds to this with the transaction monitor A4 (time T29). on the other hand,
When the database management system A3 is also ready to complete the transaction, the transaction monitor A
4 is notified (time point T30). As described above, the transaction monitor A4 confirms the completion of preparations of the database management systems A3 and B3.

Thereafter, the transaction monitor A4
Transaction management is completed by database management system A3
And transaction monitor B4 (time point T3
1, T32). The transaction monitor B4 notifies the database management system B3 of this (time point T3).
3). When the database management system B3 performs the update process and the transaction end is completed, the database management system B3 sends a response to that effect to the transaction monitor B4 (time T34). The transaction monitor B4 responds to this by the transaction monitor A4 (time point T35). On the other hand, when the transaction monitor A3 also performs the updating process and the transaction end is completed, the transaction monitor A4 is notified of that fact (time point T36). In this way, the updating of the databases A5 and B5 is surely completed. Finally,
The transaction monitor A4 notifies the update completion to the database management system A3 (time T37), and the database management system A3 further notifies the application program A2 of update completion (time T38).

FIG. 7 is an explanatory diagram of a diversion example of an existing application program. When the existing application program 71 executed on the computer A1 executes only the transaction that updates only the database A5, the commit statement and the rollback statement are issued to the database management system A3. It is assumed that the existing application program 71 is diverted when the computer B1 is connected to the computer A1 via a communication line to form a distributed database processing system. In this case, in the conventional transaction control device, all commit statements and rollback statements appearing in the application program 71 have to be searched and rewritten so that the commit and rollback are issued to the transaction monitor A4. On the other hand, in the transaction control device of the present invention, it is not necessary to modify the part of the existing application program 71, and only the newly added part 72 needs to be programmed.

[0021]

As described above, according to the transaction control apparatus of the present invention, the application program may issue a transaction end request to the database management system in the own computer regardless of whether the transaction monitor is used or not. As a result, transactions can be controlled by the same interface in either case. Therefore, it is not necessary to properly use the commit statement and the rollback statement in the application program, the programming work is facilitated, and the program mistake can be prevented. Also, when an application program intended for an existing centralized database processing system is diverted to a distributed database processing system, it is not necessary to search for a commit statement or rollback statement in the program and rewrite that part.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a transaction control device of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional transaction control system.

FIG. 3 is an explanatory diagram of a processing procedure of conventional two-phase commit control.

FIG. 4 is a block diagram showing a hardware configuration example of a transaction control device of the present invention.

FIG. 5 is a flowchart illustrating a processing procedure in a state management unit.

FIG. 6 is an explanatory diagram of a processing procedure of two-phase commit control according to the present invention.

FIG. 7 is an explanatory diagram of a diversion example of an existing application program.

[Explanation of Codes] 11, 21 Processor 12, 22 Main Storage Device 13, 23 Magnetic Disk Device 14, 15 Communication Control Device A1, B1 Computer A2, B2 Application Program A3, B3 Database Management System A4, B4 Transaction Monitor A5, B5 Database A30, B30 State management unit A31, B31 Transaction control unit A32, B32 Search / update control unit A41, B41 Storage means

Claims (1)

[Claims] 1. A transaction control device for controlling a series of processes from the start to the end of a transaction involving the update process of each database provided in each of a plurality of computers, and a transaction monitor for synchronizing the update processes. A storage unit that is provided and stores the fact that an application program that executes the transaction uses the transaction monitor, and when the application program ends the transaction, the application program ends the transaction. A database management system that receives a request, and a database management system that is provided in the database management system and is used by the application program to the transaction monitor when a transaction end request is received from the application program. A state management unit that inquires whether or not there is, and as a result of the inquiry of the state management unit, if the transaction by the application program is not used, update processing of the database in the local computer is performed.
As a result of the inquiry of the update control unit and the state management unit, when the application program uses the transaction, the transaction monitor synchronizes the databases of the plurality of computers and updates the databases. And a transaction control unit for performing the transaction.