JPH07334400A - Database access system and method of controlling the database access system - Google Patents

Abstract

(57) [Summary] [Purpose] The load is distributed to multiple gateways. You can use any character code set. When the arbitrarily set time has elapsed, the database access process is terminated. The client detects a failure of the component on the gateway or the DBMS. The gateway detects a failure of the connected client. [Configuration] A client notifies the character code set identification information of the character code used for issuing the request, and the gateway converts the character code of the request and the response. The step of accepting the access request, securing the connection with the database access language conversion means, converting the language, and sending it to the DBMS;
Disconnect the connection and notify the error. A fault monitoring request is issued in a predetermined cycle, and if the response to the request is not within the time, an error is notified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information processing system for accessing a database, and particularly to a database suitable for accessing a plurality of different database servers from a client information processing device via a network. -Access system and its control method.

[0002]

2. Description of the Related Art Along with downsizing, a database system in a company is shifting from a company-wide system using a mainframe to a department system distributed to departments in charge of each work. In the department system, in order to build the optimal system according to the work content,
Different vendor database management systems for each department
(DataBase Management System
It is not uncommon to adopt em: DBMS). On the other hand, in the execution of application software such as decision support, it is necessary to collect and analyze various data in a database distributed in each department of a company as needed.

An application programming interface (Appl) used to access a database.
ication Programming Inter
face: API), S: Structured Query La (SQL: Structured Query La)
A language called "nguage" is commonly used. The standard specifications of SQL are defined in JIS standards, but in actual DBMS products, DBMS is
The specifications are different for each vendor. Therefore, it is not possible to access databases on DBMSs of different vendors with the same SQL. Therefore, a gateway for converting one type of SQL into a SQL unique to each vendor has been commercialized. Regarding the differences in SQL specifications,
Addison-Wesley Publishing
“THE PRAC” published by Company, Inc.
TICAL SQL HANDBOOK "329-34
It is described on page 1.

Heterogeneous database using gateway
A conventional example of an access system is shown in FIG. In this conventional example, the application software execution means 11
The client information processing apparatus 110 on which the No. 1 operates has a gateway function. In the example shown in FIG. 2, the LAN (L
ocal Area Network) 100 has 2
Two server information processing devices 120a and 120b are connected to each other, and DBMS_A 121a and DBMS_A 121a, respectively.
B121b operates. An external storage device 124a that holds the data of the database 124a is connected to the server information processing device 120a, and the server information processing device 120b is connected.
An external storage device 124b that holds the data of the database 124b is connected to the. DBMS_A121
a and DBMS_B 121b manage the databases 124a and 124b, respectively.

In the access management component 112, the application software 111 is a database database.
The access destination is the SQL statement issued for access
When the access destination is the DBMS_B 121b, the SQL conversion unit A 115a operates to hand over to the respective components of the SQL conversion unit A 115a.

Each component of the SQL conversion means A 115a and the SQL conversion means B 115b receives the SQL.
Converts the sentence to the specifications of the target DBMS (access destination DBMS), and uses the database driver A for each DBMS
The converted SQL statement is transmitted to the server information processing apparatus 120a or 120b of each target via the 122a, the database driver B 122b, and the LAN driver 123.

The database driver A 122a, the database driver B 122b, and the LAN driver 123 are the same as the client information processing device 110, and are also installed in the respective server information processing devices 120a and 120b. The LAN transmitted by the client information processing apparatus 100
The SQL statement addressed to DBMS_A 121a or DBMS_B 121b is extracted from the packet data on 100, and the SQL statement is sent to each DBMS. The processing result in each DBMS follows the above route in reverse, and the SQL conversion means A
After being converted into a standard data format and a standard return code by 115a or SQL conversion means B115b, it is sent to the application software 111 via the access management component 112.

As described above, by realizing the gateway function by the access management component 112 and the SQL conversion means A 115a and SQL conversion means B 115b on the client information processing apparatus 110, a single SQ is obtained.
DBMS with different SQL specifications using only L specifications
It is possible to access.

FIG. 3 shows a conventional example in which these gateway functions are realized not by using the client information processing apparatus 110 but by using a dedicated gateway information processing apparatus 130. In this conventional example, the SQL statement issued by the application software execution unit 111 is first sent to the gateway information processing apparatus 130 via the database driver C122c and the LAN driver 123. On the gateway information processing device 130, the LAN driver 1
23, the database driver C122c retrieves the SQL statement, and the access management component 1
Sent to 12. The subsequent operation is the same as that of the conventional example described with reference to FIG. 2, and the SQL conversion means A115a, S115.
QL conversion means B115b, database driver A1
The database on the target server information processing device 120a or 120b is accessed via 22a, the database driver B 122b, and the LAN driver 123, and the result is returned to the application software execution means 111 on the client information processing device 110.

These heterogeneous database access systems are described in "Nikkei Electronics, February 15, 1993", pages 138 to 145 (published by Nikkei BP).

[0011]

As described above, the gateway information for converting the SQL statement into the SQL specification of the target DBMS is installed on the client information processing device or for realizing the gateway function. By providing the processing device, a single S
A plurality of Ds having different SQL specifications by means of application software execution means corresponding only to the QL specifications
It is possible to access the database managed by BMS.

However, in the conventional configuration shown in FIG. 2, it is necessary that all the clients have the SQL conversion means and the database driver corresponding to the DBMS to be accessed. Therefore, it is necessary to maintain the SQL conversion means and the database driver of each client each time the type of DBMS in the system is added or the version is upgraded, which is not good in maintainability.

In the conventional configuration shown in FIG. 3, only the SQL conversion means and the database driver on the gateway information processing device need be maintained, so that the above-mentioned problem is solved. However, since the database is always accessed through the gateway information processing device, the load is concentrated on the gateway information processing device and the traffic on the LAN increases, so the access performance is higher than when the gateway information processing device is not used. There was a problem that it decreased.

Further, in the conventional method using the gateway information processing device, there is a problem that a plurality of clients issuing SQLs having different specifications cannot access a plurality of DBMSs having different specifications.

Further, in the method using the conventional gateway information processing apparatus, the client application
There is a problem that different character code sets cannot be used for each software.

Further, access to the database may require a time of 30 minutes or more at a long time, and it is desirable that the user can freely set the processing termination time. However, conventionally, there has been a problem that the cutoff time cannot be set or is set to a value fixed by the system and cannot be set for each user.
Further, in the database access via the SQL conversion means on the gateway information processing device, there is a problem that it is not easy to identify the cause location when the processing termination time is exceeded. Further, even when a component or DBMS on the gateway information processing device has a failure, there is a problem that the failure is not revealed unless the waiting time is set to a value of about 30 minutes.

Further, in the method using the conventional gateway information processing device, it is difficult for a plurality of clients issuing SQLs having different specifications to access a plurality of DBMSs having different specifications.

Therefore, the present invention provides a client and a DBMS that issue database access languages having different specifications.
To provide a database access system having a language conversion means that enables access to the information processing system and capable of distributing the load associated with the language conversion to a plurality of information processing devices, and A first object is to provide a control method therefor.

Furthermore, the present invention provides a client and a DBMS that issue database access languages having different specifications.
A database access system having a language conversion means for enabling access to a database access system in which the application software can use a character code different from that of the database management system or the gateway information processing device. A second object is to provide the same and a control method thereof.

Further, the present invention is a database access system having a language conversion means for enabling a client issuing a database access language having different specifications and a DBMS to access the database at an arbitrary time. A third object of the present invention is to provide a database access system capable of aborting access processing and a control method thereof.

Furthermore, the present invention provides a client and a DBMS that issue database access languages having different specifications.
To provide a database access system having a language conversion means for enabling access to a device, and a database access system having means for detecting a failure of each device, and to provide a control method thereof. The fourth purpose.

[0022]

In order to achieve the above object, according to the present invention, a plurality of server information processing devices having a database management system that receives an access request to a database in a database access language and returns a response, A database access system comprising: one or more client information processing devices, each of which is connected to the server information processing device, is provided with an application software execution unit for issuing the request for accessing the database management system. A gateway information processing apparatus that receives the access request and sends it to the database management system, the gateway information processing apparatus receives the access request, converts the access request into a request in a different database access language, and manages the database. Database access language conversion means for sending to the system, and access management means for receiving the access request and sending it to the database access language conversion means, and a database access system having the following elements according to its purpose: Will be provided.

A. To achieve the first goal above,
(1) The client information processing apparatus accepts a request issued by the application software execution means, determines which of the plurality of access management means to send, and sends the request to the determined access management means.
(2) The access management means accepts a request issued by the application software execution means, determines which of the plurality of database language conversion means to send, and the determined database A database access system is provided which comprises at least one of having a second selection means for sending to an access language conversion means.

B. To achieve the second goal above,
(1) The client information processing device includes means for notifying the access management means of the character code set identification information of the character code used for issuing the request by the application software execution means, and the access management means. Means for converting the character code of the received request into a character code of a predetermined character code set before sending to the database access language conversion means, and a response for notifying the client information processing device, And means for converting into the character code of the notified character code set (2) means for converting the received character code of the request into a predetermined character code by the database access language conversion means , The response to notify the access control means, the notified character And / or means for converting to a character code of the code set.

C. To achieve the third purpose,
(1) When the client information processing device issues the request, it secures a connection with the access management means, sends the request to the access management means, and responds even if a predetermined time has elapsed. If there is not, a means for disconnecting the connection and setting the request processing as an error is provided (2) When the access management means receives the request, secures a connection with the database access language conversion means. If there is no response from the means for sending the request to the database / access language conversion means, the connection is disconnected, and an error in the processing of the request is sent to the client information processing device. (3) When the database access language conversion means receives the request, the database management system Means for sending a request to the database management system by securing a connection with the dan, and disconnecting the connection if there is no response after a predetermined time elapses, and managing the error in the processing of the request by access control. A database access system comprising: means for notifying a means.

D. To achieve the fourth objective,
(1) The client information processing apparatus issues a predetermined access request for failure check every time a predetermined time elapses, failure check means for sending to the gateway information processing apparatus, and the failure. If the response to the check access request is not within a predetermined time, the application / software execution means should be provided with a failure notification means. (2) The access management means should be provided for the failure check. If the access request is issued every time a predetermined time has elapsed and the failure check means for sending to the database access language conversion means and the response to the failure check access request are not within the predetermined time. Error to the client information processing device (3) The database access language conversion means issues the access request for failure check every predetermined time, and sends it to the database management system. And a failure notification means for notifying the access management means of an error if the response to the failure check access request is not within a predetermined time. Will be provided.

Further, according to the present invention, there is provided a control method for a database access system including the above-mentioned elements.

[0028]

Operation: The access management means requests access to the database management system by SQL of a predetermined specification by a remote procedure call ((Rem
access as a parameter of (Ote Procedure Call: RPC), and the target D
SQ corresponding to the type of DBMS by determining the type of BMS
RP with SQL of standard specification as a parameter for L conversion means
Issue C.

The SQL conversion means is a standard specification SQ delivered by the RPC issued from the access management means.
L is a non-standard SQL used by the target DBMS
And execute access to the DBMS.

In this way, the connection between the access management means and the SQL conversion means is performed using the RPC, and the parameter specifications of each RPC for the processing request to the access management means and the processing request to the SQL conversion means are the same. By doing
When the target DBMS is clear and single, the user application software can directly access the SQL conversion means without going through the access management means. This can reduce overhead.

Further, the access management means and the SQL conversion means can be placed on a plurality of information processing devices, and the RPC from the access management means on the first information processing device to the SQL conversion means on another information processing device. It is also possible to request processing by. As a result, the processing load can be distributed to a plurality of information processing devices. Further, it is not necessary to mount the SQL conversion means corresponding to all kinds of DBMS on all the information processing devices equipped with the access management means, and the SQL conversion means of the kind required on any one of the information processing devices. Since it is sufficient to prepare and place it, installation and maintenance are easy.

Further, the user application software runs on an information processing apparatus (client information processing apparatus),
The SQL issued from the software execution means is changed to RPC.
The client SQL processing means for making an execution request to another information processing apparatus by using the RPC with SQL as a parameter issued from the user application software execution means is a target DBMS when the RPC is for a single DBMS. It is issued to the SQL conversion means on the same information processing device, and when it is not for a single DBMS, it is issued to the access management means on the gateway information processing device different from the target DBMS.
This allows access to a single DBMS
It can be executed without incurring the overhead of passing through the gateway information processing device.

The access management means accepts an access using SQL of a predetermined specification as an RPC parameter, determines the type of the target DBMS, and
The RPC having the same content as the RPC is issued to the SQL conversion means corresponding to the type of MS. The SQL conversion means is an SQ used by the target DBMS for the access request delivered by the RPC issued from the access management means.
It is converted into an L-specific access request, and the access to the DBMS is executed. At this time, the character code set identification information is notified. The access management component converts the SQL sentence received from the application software into a character code set that can be interpreted by the access management component using the character code conversion means. As a result, the application software on the client information processing device
Various character code sets can be used for each connection to the database.

When the above-mentioned request is received by any one of the client information processing device, the access management means, and the database / access language conversion means, the connection to the destination is secured, the means for sending the request, and the predetermined time. If there is no response even after a lapse of time, if a means for disconnecting the connection and notifying the requester of the error in the processing of the above request is provided, the database access processing can be performed within a predetermined time (abort time). Can be discontinued. Further, if the client information processing device notifies the access management means, and the access management means notifies the database access language conversion means of the cutoff time for each request notification, each request by the application software execution means: Can be freely set for each connection to the database.

Further, the abort time setting means operates so as to set a time shorter than the time received from the database access processing abort time notifying means as the process abort time. As a result, the processing termination time used by the two termination time measuring means is shorter when applied to the processing request of the SQL statement from the access management means to the SQL conversion means. As a result, it is possible to prevent the processing of the access management means from being terminated before the processing request to the SQL conversion means ahead of the access management means of the application software is terminated. By this, SQL
Even when the processing termination to the conversion means occurs, the application software can receive the notification of the termination via the access management means, and the cause location can be identified when the processing termination time is exceeded.

Further, the server fault checking RPC issuing means periodically issues a fault checking RPC to the access managing means and the SQL converting means after the application software connects to the database.
The RPC for failure check, after being issued, checks by the abort time measuring means whether or not there is a response from the server, that is, the access management means or the SQL conversion means, within the abort time. If there is no response within the cutoff time, it is considered that the server has failed. This makes it possible to detect a failure in the access management unit and the SQL conversion unit before the SQL statement is issued.

Further, the means for checking the periodical issuance of RPC monitors whether or not the fault checking RPC issued from the server fault checking RPC issuing means is regularly issued, and the issuance is performed. If not, the client is considered to have failed. This makes it possible to easily detect a failure on the client side.

[0038]

Embodiments of the present invention will be described below with reference to the drawings.

(Example 1) A. Configuration of Heterogeneous Database Access System FIG. 1 shows an example of the configuration of the heterogeneous database access system in the first embodiment. The heterogeneous database access system according to the first embodiment includes a client information processing device 110 and a gateway information processing device 13.
0, the server information processing devices 120a and 120b, and the name server information processing device 150. Each of the above information processing devices 110, 120a, 120b, 130, 150
Are connected by the LAN 100. As shown in FIG. 39, each information processing device 110, 120a, 120b, 13
0 and 150 each include at least a main storage device 1001 and a central processing unit (CPU) 1000.

The client information processing apparatus 110 includes an application / software execution unit 111 and an RPC.
The remote procedure call (Re, which is an access request for accessing the data held in the database by the application software execution unit 111, including the driver 102 and the LAN driver 123.
mote Procedure Call: RPC)
Is an information processing device that receives a response to the request. Application software execution means 1
11, an RPC driver 102, and a LAN driver 12
3 is realized by the CPU 1000 of the client information processing apparatus 110 executing the instructions stored in the main storage device 1001 of the client information processing apparatus 110.

The server information processing device 120a is a DBMS
_A121a, the database driver A122a,
The server information processing device 1 including the LAN driver 123.
20 b includes a DBMS_B 121 b, a database driver database driver B 122 b, and a LAN driver 123. Server information processing device 120a, 1
20b is DBMS_A121a, DBMS_B121
b, responds to the received database access request. DBMS_ of server information processing device 120a
A121a, database driver A122a, and L
The AN driver 123 is the server information processing device 120a.
It is realized by the CPU 1000 of the server information processing apparatus 120a executing the instructions stored in the main storage device 1001 of the above. Server information processing device 1
The DBMS_B 121b of 20b, the database driver database driver B 122b, and the LAN driver 123 are realized by the CPU 1000 of the server information processing device 120b executing the instructions stored in the main storage device 1001 of the server information processing device 120b. It

The name server information processing device 150 includes a name server 151, an RPC driver 102, and a LAN driver 123, and each server component (access management component 112v) called by the RPC.
Also, the name server 151 that performs a service of providing the correspondence information between the identification information of the SQL conversion means 115) and the physical position on the network operates. Name server Name server 1 of information processing device 150
51, RPC driver 102, LAN driver 12
3 is realized by the CPU 1000 of the name server information processing device 150 executing the instructions stored in the main storage device 1001 of the name server information processing device 150.

The gateway information processing device 130 and the access management component 112v and two types of database access language conversion means (in this embodiment, SQL is used as the database access language, so they are called SQL conversion means here). In this embodiment, there are SQL conversion means A115a and SQL conversion means B115b) and a database driver (database driver A122a and database driver B122b).
And a RPC driver 102 and a LAN driver 123, and is a gateway for processing the RPC. The access management component 112v of the gateway information processing device 130, the SQL conversion means A115 and a, the SQL conversion means B115b, and the database driver A122a.
The database driver B 122b, the RPC driver 102, and the LAN driver 123 convert the instructions held in the main storage device 1001 of the gateway information processing device 130 to the gateway information processing device 1
It is realized by the CPU 1000 of 30 executing.

The access management component 112
v and the RPC driver 102 of the gateway information processing device 130 are collectively referred to as access management means.

DBMS_A 121a, DBMS_B12
The data of the database managed by 1b is
It is stored in the external storage device in the same manner as the above-mentioned conventional example,
In order to prevent the figure from becoming complicated, the external storage device and the database are not shown in FIG. 1 (the same applies to the following embodiments).

B. Processing of SQL_RPC The database access from the application software execution means 111 corresponds to the SQL statement issued by the application software execution means 111.
PC (RPC specified by the SQL statement as a parameter.
Hereinafter, it will be referred to as SQL_RPC).

The SQL specification used by the application software executing means 111 will be referred to as the standard specification in the system of the first embodiment.
In the first embodiment, DBMS_A 121a and DBMS_B
121b uses SQL specifications different from the standard specifications.

When SQL_RPC is issued from the application software execution means 111, the RPC driver 102 on the client information processing apparatus 110 first processes this SQL statement on the name server 151 on the name server information processing apparatus 150. Query the server's network address and port number for connecting to the server component.

In the first embodiment, since the server that processes this SQL_RPC is the access management component 112v on the gateway information processing device 130, the name server 151 responds to this inquiry by the network of the gateway information processing device 130. -Returns the address information and the port number of the access management component 112v.

Based on these pieces of information, the RPC driver 102 on the client information processing device 110 makes an RPC connection with the access management component 112v on the gateway information processing device 130, and the SQL_R to be processed.
Request the processing of the PC to the access management component 112v.

The access management component 112v is
The name server 151 is notified of the name of the target DBMS included in the parameter of the SQL_RPC requested to be processed, and the SQL conversion component to be used is inquired. In the first embodiment, the name server 151 uses the SQ
L conversion means A115a or SQL conversion means B115
Since the network address information of b and the port number are returned, the access management component 112v, based on the information returned from the name server 151, sends the SQL statement to any SQL conversion unit defined by the information. RPC conversion and access processing to the target DBMS
To request.

The access result to each DBMS performed by the SQL conversion unit A115a or the SQL conversion unit B115b follows the above-mentioned route in reverse, and the SQL conversion unit A11 is executed.
5a or SQL conversion means B115b, after converting to a standard data format and a standard return code, it is sent to the application software execution means 111 via the access management component 112v.

The above-mentioned SQL_RPC processing is shown in the flowchart of FIG. (1) Processing of RPC driver 102 Application of client information processing device 110
When the software 111 issues SQL_RPC, the RPC driver 102 of the client information processing device 110
First, in the name server 151 on the name server information processing device 150, the name server 151 physical location of the server that processes the SQL_RPC, that is, the network address and the server.
Queries the component port number (Step 4)
50), using the obtained port number, access management component 11 on the gateway information processing device 130
The RPC connection with the 2v is performed, and the access management component 112v is requested to process the SQL_RPC (step 451).

(2) Processing of the name server 151 The name server information processing device 150 of this embodiment has a server information table that holds identification information, addresses, etc. of server components. FIG. 35 shows an example of the server information table of the first embodiment. The server information table is
For each server component name storage area (column 1701), address storage area (column 1702), port number storage area (column 1703), and status storage area (column 1704)
And has an array structure including. The status of each component is held in the status storage area (column 1704), and is "RUN" for the operating server, "STOP" for the stopped server, and "F" for the failed server.
"AULT".

The name server 151 which has received the inquiry about the physical position of the server in the above step 450 and the like.
Refers to this server information table, and if the value held in the status storage area is "RUN", the network address and port number of the server component held corresponding to the inquired name. And reply.

(3) Access management component 112
Processing of v Steps 401 to 411 are processing contents of the requested access management component 112v. Step 4
Access management component 112 requested by 51
First, v analyzes the SQL statement sent as the parameter of SQL_RPC and obtains the name of the DBMS including the table of the access destination (step 401).

In the first embodiment, the access management component 112v does not only operate on a table on a single DBMS, but also searches for data in a plurality of tables across a plurality of databases managed by different DBMSs.
Made it possible to perform operations such as combining. Therefore, the access management component 112v of the first embodiment determines whether the access destinations are both the DBMS_A 121a and the DBMS_B 121b (step 402), only the DBMS_A 121a (step 403), or only the DBMS_B 121b (step 404).

The access destination is DBMS_A 121a and DB
In both cases of the MS_B 121b, the access management component 112v sends the SQL statement to be processed to the DBMS_A.
An SQL statement divided into access to 121a and access to DBMS_B 121b is created (step 406). Next, the access management component 112
v executes RPC (referred to as SQL_A_RPC) with the SQL statement for DBMS_A 121a as a parameter, obtains the result (step 407), and further executes the DBMS.
R with the SQL statement for S_B121b as a parameter
Executes PC (referred to as SQL_B_RPC) and obtains the result (step 408). Finally, the access management component 112v merges the results obtained in steps 407 and 408 to create a result corresponding to the SQL statement before division (step 409), and completes the SQL_RPC processing (step 412). ).

When the access destination is only one of the DBMS_A 121a, the access management component 112v uses the SQL statement to be processed as a parameter in the RPC (SQL_SQL_A).
A_RPC) is issued to get access result (step 4
10), the process of SQL_RPC is completed (step 4)
12).

When the access destination is only one of the DBMS_B 121b, the access management component 112v uses the SQL statement to be processed as a parameter for the RPC (SQL_SQL).
B_RPC) to issue access result (step 4
11), the processing of SQL_RPC is completed (step 4)
12).

The access destination is DBMS_A 121a.
If it is neither the DBMS_B 121b nor the DBMS_B 121b, the access management component 112v sets an error code (step 405) and ends the SQL_RPC processing (step 412).

(4) Division of SQL_RPC (step 4
06) The access management component 112v is the processing target S
When it is detected that the QL statement contains processing instructions for multiple databases, SQL divided for each access target
Create _RPC (step 406). The SQL statement created by the access management component 112v will be described using the example of the select syntax shown in FIG. The select syntax is a question specification for searching a record satisfying the condition specified by the WHERE clause from the access target described in the FROM clause and obtaining a table having the data specified in the SELECT clause of the record as a constituent element. Is the syntax.

The SQL statement 2301 issued by the application software execution means 111 is "DBMS_".
A table named "SALES" managed by a database management system named "A" and "DBMS_B"
Managed by a database management system named "S"
From the table called "ALESDATA", select "SaleN
The record in which the content of the "um" column is not 0 is searched, and the content of the "Name" column of the record and "SaleNu" are searched.
It is an instruction to create a table with the contents of the m "column.

The access management component 112v is
This SQL statement 2301 is changed to the SQL for DBMS_A.
Statement 2302 and SQL statement 2303 for DBMS_B
RP with each SQL statement as a parameter
C is issued and the responses are combined to create a table that is a response to the SQL statement 2301.

The SQL statement 2302 is "SA" managed by the database management system named "DBMS_A".
This means that a record in which the content of the “SaleNum” column is not 0 is searched from the table “LES”, and a table of the content of the “Name” column and the content of the “SaleNum” column of the record is created.

The SQL statement 2303 is "SA" managed by the database management system named "DBMS_B".
From the table called “LESDATA”, select “SaleNu
The record in which the content of the m "column is not 0 is searched, and the content of the" Name "column of the record and" SaleNu "are searched.
Means to create a table with the contents of the m "column.

(5) SQL_RPC processing for instructing access to a single DBMS (steps 407, 410 (S
Processing of QL_A_RPC), Steps 408 and 411
(Processing of SQL_B_RPC)) SQL_RPC for instructing access to a single DBMS
The processing of (hereinafter, referred to as SQL_x_RPC) is shown in FIG. In the process of SQL_x_RPC, first, the RPC driver 102 of the gateway information processing device 130 makes the SQ
A server component that processes L_x_RPC (in the first embodiment, the SQL conversion means A115a or SQL
The network address information and the port number of the conversion means B115b) are inquired to the name server 151 and acquired as a response to the inquiry (step 50).
1).

Next, the RPC driver 102 of the gateway information processing apparatus 130 sends SQL to the SQL conversion means 115 detected by the inquiry in step 501.
_X_RPC is delivered and its processing is requested (step 502).

In the first embodiment, the RPC driver 102 inquired in step 501,
SQL conversion means A115a and SQL conversion means B11
5b and the same gateway information processing device 13
Since it is 0, the RPC driver 102 does not need to use the network address information and the port number,
QL_x_RPC can be notified to the SQL conversion means 115. Therefore, in the first embodiment, step 501
The process of may be omitted.

Steps 503, 504 and 505 are the processing of the SQL conversion means 115 requested to be processed. SQL
The conversion unit 115 converts the standard SQL statement received as the RPC parameter into the SQL specification of the target DBMS (step 503). Next, the SQL conversion means 115 sends the SQL sentence created by the conversion to the target DBMS, and the SQL in the target DBMS is sent.
A statement execution result is obtained (step 504). Furthermore, SQ
The L conversion means 115 converts the data obtained as the execution result and the return code from the SQL specification of the target DBMS to the standard SQL specification (step 505). Finally, the SQL conversion means 115 ends the processing of SQL_x_RPC using the conversion result as return data and a return code (step 506).

Next, conversion of the SQL sentence (step 503) by the SQL conversion means 115a and 115b will be described using the example shown in FIG. SQL conversion means 115a, b
Converts the input SQL syntax into the SQL specification of each target DBMS. In step 505, the reverse conversion is performed.

In the standard SQL of the first embodiment, the operator indicating "not equal" is "<>", but in the SQL specification of the DBMS_A 121a, "! =".
In the SQL specification of DBMS_B 121b, "^ ="
Is used. In this case, the SQL conversion means A115a
Is a standard SQL statement 2302 (shown in FIG. 23),
The conversion is performed as shown in the syntax 2402 in FIG. That is, the SQL conversion means A 115 a uses the syntax 2302 “<
> ” = ". Also, SQL conversion means B1
15b converts the standard SQL statement 2303 (shown in FIG. 23) as shown in the syntax 2403 of FIG.
That is, the SQL conversion unit B115b has the syntax 2302.
"<>" Of is converted to "^ =".

As described above, the access management component 112v, SQL conversion means A115a, SQL
By including the conversion unit B115b, the application / software execution unit 111 uses a single SQL statement of the standard specifications for the tables on the plurality of DBMSs having different specifications without being aware of the difference in the specifications. Can be accessed.

(6) Generation and Deletion of Processes in Gateway Information Processing Device 130 FIG. 10 shows an example of the operation of the program in the gateway information processing device 130 in the first embodiment. here,
Two client information processing devices are connected, and the client information processing device 110a is connected to the server information processing device 120.
The case where the DBMS_A on the server a and the DBMS_B on the server information processing device 120b are accessed, and the DBMS_B on the server information processing device 120b is accessed from the client information processing device 110b is shown.

In the access management component 112v, a process is created for each connection with the client information processing device. Also for the SQL conversion means A 115a and the SQL conversion means B 115b, a process is generated each time an access request from each process of the access management component 112v is issued using RPC. Further, the database driver A 122a and the database driver B 122b are respectively SQL conversion means A115.
a, one process of the SQL conversion means B115b operates so that one process is generated.

These processes disappear with the end of access. By causing the gateway information processing device 130 to perform such process generation / destruction, it is possible to simultaneously process access from a plurality of client information processing devices to a plurality of server information processing devices.

C. Application Example Two existing systems 6 having database management systems having different specifications in the network 100
Network 10 in which 00a and 600b are connected
An example in which the heterogeneous database access system of the first embodiment is applied to 0 will be described with reference to FIG.

The system 600a is a client information processing apparatus 1 having a server information processing apparatus 121a using DBMS_A, a database driver A dedicated to DBMS_A, and application software A executing means.
It is composed of 10a. Also, the system 600b is D
Server information processing device 121b and DB using BMS_B
It comprises a database driver B dedicated to MS_B and a client information processing device 110b on which application software B is installed.

By adding the additional system 500 including the gateway information processing device 130, the name server information processing device 150, and the client information processing device 110 to these existing systems, the existing systems 600a and 600b are configured. Without changing anything
From the added client information processing device 110, a plurality of DBMs having different specifications can be used by using a single SQL statement of standard specifications.
S can be accessed.

(Second Embodiment) By the way, in the present invention, RPC is used for the access to the access management component 112v from the application software execution means 111 and the access to the SQL conversion means 115 from the access management component 112v. . For this reason,
The addition of the gateway information processing device 130 can easily avoid the deterioration of the database access performance due to the load concentration on the gateway information processing device 130 in the heterogeneous database access system shown in the first embodiment. In the second embodiment, the gateway information processing device 13
An example in which 0 is added will be described.

In the second embodiment, as shown in the configuration diagram of FIG. 9, two gateways, that is, a gateway information processing device 130a equipped with the SQL conversion means A115a and a gateway information processing device 130b equipped with the SQL conversion means B115b. The information processing device is connected to the network 100. That is, the second embodiment is based on the SQL conversion means 1.
It differs from the first embodiment in that a gateway information processing device 130 is provided for each 15.

RP on client information processing device 110
Similar to the first embodiment, the C driver 102 uses SQL_R issued by the application software execution unit 111.
When the PC is accepted, first, the name server 151 is inquired about the physical location of the server that processes the SQL_RPC, that is, the network address and the port number.

The server information table of the second embodiment is shown in FIG.
As shown in 7, information on a plurality of servers (address, port number,
And state) are retained. Therefore, the name server 151 of the second embodiment refers to the server information table 1700 and returns the network addresses and port numbers of all the operating server components corresponding to the specified server component name. That is, the name server 151 holds all the server component names specified in the column 1701 and all the rows in which “RUN” is held in the column 1704,
The data (network address) held in the column 1702 and the data (port number) held in the column 1703 are returned.

In the second embodiment, the server that processes the SQL_RPC, that is, the access management component 11
2v is a gateway information processing device 130a and 130b
And the name server 151 returns the physical positions of the two access management components 112v in response to the inquiry. The RPC driver 102 on the client information processing apparatus 110, as a first selection unit, selects one from the plurality of returned access management components 112v and requests processing.

The processing of each component of the heterogeneous database access system of the second embodiment is the same as that of the first embodiment except for the processing particularly described here.

A. Operation Example Next, an operation when the access management component 112v on the gateway information processing device 130a is selected will be described.

The SQL_RPC issued from the application software execution means 111 is first sent to the access management component 112v on the gateway information processing device 130a by the RPC driver 102 of the client information processing device 110.

As described above with reference to FIG. 4, the access management component 112v of the gateway information processing device 130a determines whether SQL_A_RPC and / or SQL_A_RPC is set according to the target DBMS of the received SQL_RPC.
Or issue SQL_B_RPC. The access management component 112a then issues the issued SQL_x.
If _RPC is SQL_A_RPC, the SQL conversion unit A115a is notified and processed, and issued SQL_x.
If _RPC is SQL_B_RPC, the SQL conversion means B115b is notified and processed.

In the system of the second embodiment, the SQL is
The SQL conversion means B115b for processing _B_RPC is
Access management component 112a requested to process
Exists in a gateway information processing device 130b different from the gateway information processing device 130a in which Therefore, the RPC driver 102 of the gateway information processing device 130a notifies the SQL_B_RPC to the SQL conversion means B115b on the gateway information processing device 130b via the LAN 100. Multiple SQL conversion means B
In the system including 115b, the RPC driver 102 of the gateway information processing device 130a serves as the second selecting unit and operates as the client information processing device 11 described above.
The SQL conversion unit B115b to be notified may be selected by the same procedure as that of the 0 RPC driver 102.

As described above, in the second embodiment, the RPC driver 102 on the gateway information processing device 130 is used to access the SQL conversion means 115.
However, since the SQL conversion unit 115 requesting the processing is selected, even if the SQL conversion unit 115 is distributed over a plurality of gateway information processing devices 130, the application / software execution unit 111 does not need to be aware of the position. Can be accessed. Therefore, the SQL conversion means 115 corresponding to various DBMS existing in the system may be in any of the gateway information processing devices 130 in the system, and all SQL conversion means 1
It is not necessary for each gateway information processing device 130 to have 15. As a result, each gateway information processing device 13
It is possible to avoid the concentration of load on 0, introduce the SQL conversion means 115, and reduce the number of maintenance steps.

B. Selection method RPC driver 1 on client information processing device 110
02 executes selection of the access management component 112v and notifies SQL_RPC. In addition, the RPC driver 102 on the gateway information processing devices 130a and 130b uses the SQL conversion means A115a or SQL.
The conversion means B115b is selected, and SQL_x_RP is selected.
Notify C. Therefore, an example of a method of selecting a notification target of the RPC driver 102 when a plurality of candidates are returned from the name server 151 as a result of an inquiry to the name server 151 will be shown below.

(1) Random Selection The first selection method is a method of randomly selecting from a plurality of candidates. As shown in FIG. 12, when the number of candidates is 2 or more (step 1201), a random number is generated (step 1202), the random number is divided by the number N of candidates, and the remainder is calculated (step 1203). A method of selecting the second candidate as a server component (step 1204) can be considered.

(2) Selection Based on Priority Order The second selection method is to use the priority order registered in advance. In this method, the priority order of the server components is set in the RPC in a table format as shown in FIG.
The RPC driver 102 is stored in advance in a file that can be referred to by the driver 102, and the RPC driver 102 uses the name server 151.
The server component with the highest priority is selected from the plurality of candidates returned from the server component.

A column 1301 in FIG. 13 is a priority order, and a column 1302 is a server name storage area. When using this method, when the server component exists on the same information processing device as the component that issues the RPC,
Setting the server component to a high priority will reduce the overhead of going through the network.

(3) Selection According to Load State The third method is for each gateway server information processing device 13
This method is selected depending on the load state of 0. The load state means, for example, the gateway server information processing device 13
The CPU occupancy rate of instructions of all programs operating at 0 and the frequency of access to the external storage device. When this method is used, load information notification means (not shown) for returning the load status of the CPU, external storage device, etc. provided by the operating system (OS) of each gateway server in response to an inquiry It is provided in the gateway server information processing device 130. Further, a server component (access management component 11) is stored in a storage area (not shown) of each RPC driver 102.
2v or SQL conversion means 115) number of candidates (N) storage area, counter variable (c) storage area, minimum load server number storage variable (n) storage area, minimum load The storage area includes a storage variable (denoted as LMIN) and a storage area for a variable (denoted as L) indicating a load state. FIG. 1 shows the procedure of the selection process according to the third method.
4 shows. The load information notifying unit is realized by the CPU of the gateway server information processing device 130 executing the instructions held in the main storage device 1001 of the gateway server information processing device 130.

The RPC driver 102 initializes the server component candidate number N storage area, the counter variable c storage area, the minimum load server number storage variable n storage area, and the minimum load storage variable LMIN storage area (step 1401). . The initialization in step 1401 means storing an initial value in each storage area. In the second embodiment, the initial value of the server component candidate number N is the notified number of candidates and the counter variable c. And the initial value of the minimum load server number storage variable n is 1, respectively.
The initial value of the minimum load storage variable LMIN is 100.

Next, the RPC driver 102 checks whether or not there are a plurality of server component candidates, and if there is only one, there is no need to check the load, so control is transferred to step 1410, and the selection result is listed as a candidate. Server component (step 1402).

When there are a plurality of server component candidates, the RPC driver 102 inquires the load information notifying means of the gateway server information processing device 130, which is equipped with the c-th candidate server component, about the load information (step). 1403), the numerical value indicating the load state returned from the server component is stored in the storage area of the variable L (step 1404). Here, the numerical value indicating the load state is represented by a numerical value (percentage) from 0 to 100. For example, the gateway server information processing device 13
The value increases as the number of programs executed in parallel at 0 increases. On the other hand, when there is no program being executed, the value is close to 0.

Next, the RPC driver 102 compares the minimum value LMIN of the load of the other servers that has been checked up to that time with the variable L (step 1405). If the variable L is smaller, LMIN is set to LMIN. Stores the value of (step 140
6) Store the candidate number of the server component that has been investigated, that is, the value of c in the minimum load server number n (step 1407). After that, the RPC driver 102 increments the value of the counter variable c by 1 (step 1408), checks whether or not the load examination has been completed up to the last candidate (step 1409), and if not,
Repeat steps 1403 to 1409.

In this way, the candidate number of the server component having the smallest load is held in the n storage area, so that the RPC driver 102 determines that the server component indicated by the candidate number held in the n storage area. Is selected to end the process (step 1410).

According to this method, it is possible to select a server component on an information processing device with a light load, so that it is possible to avoid the load from concentrating on one information processing device, and to execute processing at high speed. The load information notifying means may be provided for each server component. In this case, the inquiry in step 1403 is made for each candidate server component. By doing so, the server component to be used can be determined according to the load state of each server component rather than the entire information processing apparatus.

(4) Selection by Response Time The fourth selection method is a method of selection based on the response time from each gateway server information processing device 130. When this method is used, a server component (access management component 112v or SQL conversion means 1) is stored in a storage area (not shown) of each RPC driver 102.
15) Storage area for the number of candidates (N), storage area for counter variable (c), minimum response time server number storage variable (n) storage area, minimum response time storage variable (RMIN) And a response time (denoted by R) storage area. FIG. 15 shows the procedure of the selection process according to the fourth method.

The RPC driver 102 initializes a server component candidate number N storage area, a counter variable c storage area, a minimum response time server number storage variable n storage area, and a minimum response time storage variable RMIN storage area ( Step 1501). Note that step 150
The initialization in 1 is to store the initial value in each storage area. In the second embodiment, the initial value of the server component candidate number N is the notified number of candidates, the counter variable c, and the minimum load. The server number storage variable n has an initial value of 1, and the minimum response time storage variable RMIN has an initial value of 100.

Next, the RPC driver 102 checks whether or not there are a plurality of server component candidates, and if there is only one, it is not necessary to check the response time.
Control is transferred to (step 1502).

When there are a plurality of server component candidates, the RPC driver 102 sends a dummy RP for measuring the response time to the c-th candidate server component.
C is issued (step 1503), and the response time for this RPC is stored in the variable R storage area (step 150).
4).

Next, the RPC driver 102 compares the minimum value RMIN of the response times of the other server components examined up to that time with the variable R (step 1505),
If the variable R is smaller, the value of R is stored in RMIN (step 1506). After this, the RPC driver 10
2 stores the candidate number of the investigated server component, that is, the value of c in the minimum response time server number n (step 1507) and increments the counter variable c by 1 (step 1508). Further, the RPC driver 102 checks whether or not the response time has been checked up to the last candidate (step 1509), and if not done, steps 1503 to 1509 are repeated.

In this way, when the examination of all the candidates is completed (step 1509), the candidate number of the server component having the minimum response time is held in the n storage area. 102 is
The server component indicated by the candidate number n is selected, and the process ends (step 1510).

The above-mentioned response time reflects the performance and load state of the information processing apparatus in which the server component is mounted, the distance of the communication path to the information processing apparatus, the congestion degree of the communication path, etc. Optimal processing can be performed by employing the server component with the shortest response time.

(5) Selection by Response Time Using Broadcast Communication The selection of the server component by response time can be performed more easily than the above-mentioned fourth method by using broadcast communication. Using this method, each server component comprises means (not shown) that responds to a broadcast RPC that recruits server components that it can handle. FIG. 16 shows the procedure of the selection process in this method. It should be noted that the above-mentioned means for responding to the instruction stored in the main storage device 1001 of each information processing apparatus in which the means is present is a CP.
It is realized by U executing.

First, the RPC driver 102 issues a broadcast RPC requesting a processable server component (step 1601) and waits for a response (step 1602). The response to this broadcast RPC contains information about the server component that responded, so at the time of the first response,
The RPC driver 102 obtains the server name of the server component that responded from the response (step 160).
3) The server component is adopted as a server that actually requests the process, and the process is terminated (step 1).
690).

The server components that have responded after the second one are ignored. In this way, by selecting the server component to request the processing using the broadcast RPC, the performance of the information processing apparatus equipped with the server component is similar to the method of comparing the response times described as the fourth method. Also, selection can be performed by reflecting the load state, the distance of the communication path to the information processing apparatus, the congestion degree of the communication path, and the like. This broadcast RPC is issued to all servers connected to the network, but if multicast RPC is used, it can be issued only to the server component candidates obtained from the name server 151.

Furthermore, if the selecting operation is performed a plurality of times according to one or both of the above response times and the server component having the shortest average response time of a plurality of times is selected, the temporary network congestion will occur. It is possible to prevent the effects of changes in the server, etc., and select more optimal server components.

(6) Selection based on response time and load status In addition, the server component broadcasts the RP.
By changing the response time to C or the multicast RPC according to the load condition of the information processing device in which the server component is mounted, the selection of the server component by the broadcast communication or the multicast communication described in (5) is performed. , Can be done more optimally. A server according to this method will be described with reference to FIG.
The processing procedure of the component is explained. When this method is used, the response means for the broadcast communication of each server component is a storage area of a variable (L) which is a numerical value of the load state of the server information processing device having the server component. Equipped with.

First, the response means to the broadcast communication of the server component checks whether or not the received broadcast packet is the processing target of the server component, and if not, ends the processing (step 2001). If it is a processing target, the response means checks the load state of the information processing device in which the server component is mounted (step 2002), and substitutes a numerical value of the load state into the variable L (step 200).
3). Next, the response means counts down the variable L to 0 (step 2004) and delays the shift to the next process for a time proportional to the load value (step 2005). The delay process (steps 2004, 200
After 5), the response means issues a response packet indicating that the processing is possible to the client component that has requested the processing (step 2006), and broadcasts the response packet.
The packet reception process ends (step 2090).

In this way, in response to the recruitment using the broadcast communication from the client component (RPC driver 102), each server component is proportional to the load state of the information processing device in which the server component is mounted. After the delay time, the server component issues a response packet indicating that the server component can process. As a result, similarly to (5), if the RPC driver 102 selects the server component that responds earliest, it can select the server component on the information processing device with the lightest load state.

Each of the selection methods (1) to (6) described above may be used alone or in combination. Further, the name server 151 may be provided with these selecting means, and if there are a plurality of candidates, one of them may be selected, or priority may be given to reply to the inquiry source to the name server 151. May be.

In the second embodiment, it is not always necessary to mount the SQL conversion means corresponding to all kinds of DBMS on all the information processing equipments equipped with the access management means. The kind of S you need above
Since the QL conversion means may be prepared and installed, there is an effect that introduction and maintenance are easy.

Further, in the second embodiment, the access management component and the SQL conversion means can be placed on a plurality of information processing devices, and the access management component on the first information processing device can be changed to another information processing device. It is also possible to make a processing request by RPC to the above SQL conversion means. As a result, the processing load can be distributed to a plurality of information processing devices.

(Third Embodiment) In the third embodiment, the SQL conversion means A115a and the SQL conversion means B115 that were operating on the gateway information processing device 130 in the first embodiment.
b are server information processing devices 120a and 120b, respectively.
Set up in. Also in the third embodiment, the SQL conversion means A115a and the SQL conversion means B1 are similar to the embodiments already described.
The interface to 15b uses RPC. Thus, the configuration of the heterogeneous database access system of the first embodiment shown in FIG. 1 is changed to the heterogeneous database access system of the third embodiment shown in FIG. 6 while using the same server components as those of the first embodiment. The configuration can be changed. In the third embodiment, since the server information processing apparatuses 120a and 120b respectively include the SQL conversion unit A115a and the SQL conversion unit B115b, different SQLs can be obtained without a gateway information processing apparatus 130 but with a single SQL specification. DBMS_ with specifications
A121a and DBMS_B121b can be accessed.

In the third embodiment, the RPC driver 102 on the client information processing device 110 uses the SQL issued from the application software execution means 111.
As the RPC parameters, each DBMS 121a, b
SQL_API processing means 700 for accessing the database via the.

The processing of the SQL_API processing means 700 is shown in FIG. First, when the SQL_API processing means 700 receives an SQL statement issued from the application / software execution means 111, it analyzes the SQL statement,
The DBMS information of the access destination is obtained (step 701).
Next, the SQL_API processing means 700 determines whether the access destination is both DBMS_A 121a and DBMS_B 121b, only DBMS_A 121a, or DBMS_B12.
1b only (steps 702, 70)
3, 704).

If the access destinations are both DBMS_A 121a and DBMS_B 121b, the SQL_API processing means 700 issues SQL_RPC with the SQL statement to be processed as a parameter (step 706). This SQL_RPC is sent to the access management component 112v of the gateway information processing device 130, where it is processed as in the case of the first embodiment.

On the other hand, the access destination is DBMS_A 121a.
And only one of DBMS_B121b, SQL_API processing means 700, SQL_A
_RPC (step 707) or SQL_B_R
The PC (step 708) is issued to access the DBMS_A 121a or the DBMS_B 121b without going through the gateway information processing device 130.

The designated access destination is DBMS_A12
If it is neither 1a nor DBMS_B 121b, the SQL_API processing means 700 sets an error code (step 705) and ends the processing (step 709).

As described above, in the third embodiment, the gateway information processing apparatus 130 is used only when processing the SQL statement instructing simultaneous access to both the DBMS_A 121a and the DBMS_B 121b, and for one of the DBMSs. SQ to instruct access
When processing an L statement, SQL_API processing means 70
0 directly accesses the designated DBMS without going through the gateway information processing device 130. As a result, in the third embodiment, the gateway information processing device 130
It is possible to reduce the performance degradation caused by passing through.

According to the third embodiment, the target D
In the case where the BMS is clear and single, the user application software can directly access the SQL conversion means without using the access management component, so that the overhead can be reduced.

The SQL_API processing means 700 of this embodiment can also be applied to the first embodiment. As a result, in the case where the target DBMS is clear and is single, even in the first embodiment, the SQL conversion means can be directly accessed without going through the access management component, and the overhead can be reduced.

(Fourth Embodiment) In the first to third embodiments described above, a plurality of DBMSs having various SQL specifications from the application software executing means 111 having arbitrary SQL specifications.
Although the example of realizing the access to the DBMS has been shown, the fourth embodiment realizes the access to the DBMS from the application software execution means 111 using various SQL specifications.

FIG. 8 shows the configuration of the heterogeneous database access system of the fourth embodiment. In the fourth embodiment, as shown in FIG. 8, the non-standard SQL on the client information processing device 110r and the gateway information processing device 130 is added to the configuration of the heterogeneous database access system of the first embodiment shown in FIG. The conversion means 115r is added. The client information processing apparatus 110r has the same configuration as the client information processing apparatus 110, but instead of the application software executing means 111 of the standard SQL specification, the application software R executing means 111r of the non-standard SQL specification is used. Equipped with. The non-standard SQL conversion means 115r converts the non-standard SQL into the standard SQ.
It is a means for converting to L.

R containing a non-standard SQL statement issued from the application software execution means 111r
The PC (hereinafter referred to as SQL_r_RPC) uses the RPC driver 102 to connect the LAN driver 123 and the LA driver.
It is sent to the non-standard SQL conversion means 115r of the gateway information processing device 130 via N100 and processed.
The SQL statement converted from the non-standard SQL to the standard SQL by the non-standard SQL conversion unit 115r is sent to the access management component 112v as an RPC parameter. Subsequent processing is the same as that of the first embodiment. After the SQL conversion means 115 converts the SQL into the SQL of the target DBMS specifications, the DBMS is accessed by the SQL statement, and the result is the application software execution means 1
Returned to 11r.

As described above, according to the fourth embodiment, by providing the component for converting the non-standard SQL into the standard SQL, the application software execution means 111r using various SQL specifications can execute the application software execution. S different from the means 111r
It is possible to access the DBMS of the QL specification.

(Fifth Embodiment) Next, a DBMS having an SQL specification and a communication protocol specification different from that of the DBMS can be accessed without changing the program configuration of the client information processing apparatus constructed exclusively for the DBMS. A possible heterogeneous database access system will be described.

A. Configuration Example In the fifth embodiment, both a client using RPC and a client not using RPC are connected to the network 100. In the fifth embodiment, like the configuration of the heterogeneous database access system shown in FIG. 11, the client information processing apparatus 110a and the gateway information processing apparatus are added to the configuration of the heterogeneous database access system of the first embodiment shown in FIG. Non-standard SQL conversion means R on 130
Added A115ra.

The client information processing apparatus 110a includes an application software A executing means 111a,
Database driver A122a and LAN driver 1
And 23. The application software A execution unit 111a is a software execution unit of non-standard SQL specifications, and has a function of issuing a non-standard SQL statement and receiving a response. Client information processing device 110
The database driver A 122a of a notifies the database driver A 122a of the gateway information processing apparatus 130 of the nonstandard SQL statement issued by the application software A execution unit 111a. The database driver A122a is DBMS_A12.
It has the same SQL specification as 1a.

On the other hand, the non-standard SQL conversion means RA115ra of the gateway information processing device 130 converts the input non-standard SQL sentence into a standard SQL sentence and outputs it to the RPC driver 102 of the gateway information processing device 130. It is an SQL conversion means.

B. Operation In the fifth embodiment, once the database driver 122
a and the standard SQL statement converted via the non-standard SQL conversion means RA115ra is sent to the RPC driver 102 of the gateway information processing device 130, so that the database access by the SQL statement issued by the application software A execution means 111a can be performed. Done.

The specification of the DBMS_A 121a issued from the application software A executing means 111a, that is, the SQL statement of the non-standard specification is
The gateway 122 information processing apparatus 130 via the LAN driver 123 and the LAN 100 by the driver 122a.
It is sent to the above non-standard SQL conversion means RA115ra and processed. The non-standard SQL conversion unit RA115ra converts the notified non-standard SQL sentence into standard SQL and notifies the access management component 112v as a parameter of RPC. Subsequent processing is the same as that of the first embodiment.
SQ of the target DBMS specifications by the QL conversion means 115
After being converted into L, the DBMS is accessed by the SQL statement, and the result is returned to the application software execution means 111r.

As described above, in the fifth embodiment, by adding the non-standard to standard SQL conversion means to the system of the first embodiment, a non-standard SQL and a non-standard database driver specific to a certain DBMS are used. , Some DBMS
An S that is different from the DBMS is used without changing the program configuration of the client information processing device that is dedicatedly constructed.
It is possible to access the DBMS of QL specifications and communication protocol specifications.

In the fifth embodiment, the connection between the client information processing apparatus 110a and the gateway information processing apparatus 130 is made by using the database driver_A 122a. However, this driver uses an RPC having a specification different from the above RPC. May be.

C. Application Example Two existing systems 6 having database management systems having different specifications in the network 100
Network 10 in which 00a and 600b are connected
An example in which the heterogeneous database access system of the fifth embodiment is applied to 0 will be described with reference to FIG.

The system 600a is a client information processing apparatus 1 equipped with a server information processing apparatus 121a using DBMS_A, a database driver A dedicated to DBMS_A, and application software execution means A.
It is composed of 10a. Also, the system 600b is D
Server information processing device 121b and DB using BMS_B
It comprises a database driver B dedicated to MS_B and a client information processing device 110b on which application software B is installed.

These existing systems 600a, 600
b, the additional system 5 including the gateway information processing device 130 and the name server information processing device 150 described above.
Existing system 600 by adding 00
a, 600b from the client information processing apparatus 110a to the server information processing apparatus 12 without any change in the configuration.
The client information processing device 110 installed in 1b
It is possible to access DBMS_B whose SQL specification is different from that of a.

(Example 6) A. Configuration of Heterogeneous Database Access System Next, application software execution means 111
Database that can use various character code sets
An embodiment for realizing the access system will be described with reference to FIG. The configuration of the heterogeneous database access system of the sixth embodiment is similar to that of the first embodiment shown in FIG. In the sixth embodiment, the access management component 112v analyzes the SQL statement by the SQL statement analysis unit 38.
1 is provided. The SQL conversion unit 115 also includes an SQL statement conversion unit 382 for converting an SQL statement. The character code set that can be handled by the SQL statement analysis unit of the access management component 112v and the SQL statement conversion unit of the SQL conversion unit 115 is a JIS code.

B. Processing of SQL_RPC FIG. 21 shows a procedure of processing the SQL_RPC issued by the application software execution means 111 in the sixth embodiment.

(1) Processing of the RPC driver 102 The application software execution means 111 uses SQ
When L_RPC is issued, the client information processing device 1
The RPC driver 102 of 10 first determines whether or not it is a connection statement to the database (step 2161), and if it is a connection statement, steps 2150 and 21.
After executing step 62, the processing is moved to step 2151,
If the sentence is other than the connection sentence, the step 215 is directly executed.
The process is transferred to 1.

At step 2150, the RPC driver 1
An access management component 11 is a server 02 that accesses the name server 151 on the name server information processing device 150 and processes the SQL_RPC to be processed.
Obtain the 2v physical location or network address and port number of the server component. Then R
In step 2162, the PC driver 102 sends the character code set name used in the SQL statement by the application software execution unit 111 to the access management component 112v. The access management component 112v that received the character code set name
Is the storage device 100 of the gateway information processing device 130.
The input character code set name is stored in the storage area 383 in 1 (step 2121).

Finally, the RPC driver 102 makes an RPC connection with the access management component 112v,
Access management component 11 for processing QL_RPC
2v is requested (step 2151).

(2) Access management component 112
Processing of v Steps 2101 to 2111, 2121 to 2123, 2
Reference numeral 140 is the processing content of the access management component 112v.

The access management component 112v requested to process the SQL_RPC refers to the input character code set name held in the storage area 383 and refers to the SQL statement sent as the parameter of the SQL_RPC notified from the RPC driver 102. The character code is converted into a JIS code (step 2123). However, if the input character code set name notified in step 2121 is JI
In the case of S-code, conversion is not necessary and is not performed. Next, the access management component 112v analyzes the SQL sentence that has undergone the character code conversion, and obtains the name of the DBMS that includes the access destination table (step 210).
1).

As a result of this analysis, the access destination is DBMS_
When the access management component 112v detects that it is both the A121a and the DBMS_B121b (step 2102), the access management component 112v sends the SQL statement to be processed to the DBMS_A121a, as in step 406 of the first embodiment.
And the access to the DBMS_B 121b are divided into two SQL statements (step 2106). SQL_RPC (SQL_A_RPC, S respectively) using this newly created SQL sentence as a parameter
QL_B_RPC), and the access management component 112v uses DBMS_A in step 2107.
121a, in step 2108 DBMS_B121b
To access each. These DBMS 121
Upon receiving the responses from a and b, the access management component 112v causes the steps 2107 and 2108 to be executed.
The result obtained in step 2106 is merged to create a result corresponding to the SQL statement before being divided in step 2106 (step 210).
9).

When it is detected that the access destination is one of the DBMS_A 121a and the DBMS_B 121b (step 2103 or 2104), the access management component 112v, in step 2110 or 2111, uses the SQL statement as the parameter RPC (SQL_A_RPC or SQL_B_RP
C) is issued and the access result is obtained.

The access destination is DBMS_A 121a.
If it is neither DBMS_B 121b, the access management component 112v sets an error code (step 2105).

Finally, the access management component 11
2v converts the access result obtained in steps 2109 to 2111 or the error code set in step 2105 from the JIS code into the character code indicated by the input character code set name held in the storage area 383 (step 2140), as in step 412 of the first embodiment, the application software execution means 111 is used as the return value of the remote procedure call.
And ends SQL_RPC (step 211).
2).

(3) Processing of SQL_x_RPC (steps 2107 to 2108, 2110 to 2111) FIG. 22 shows a processing flow of SQL_A_RPC or SQL_B_RPC. Note that the procedure of the process of SQL_A_RPC and the process of SQL_B_RPC are the same, so here, these processes are collectively referred to as SQL_x_RP.
This will be described as C. Further, the SQL conversion unit A 115a and the SQL conversion unit B 115b, which are servers that process SQL_x_RPC, are collectively referred to as SQL conversion unit 115.

When SQL_x_RPC is notified, the RPC driver 102 of the gateway information processing device 130 is notified.
First determines whether or not it is a connection statement to the database (step 2261), and if it is a connection statement, it accesses the name server 151 on the name server information processing device 150 to determine the physical position of the SQL conversion means 115. That is, the network address and the port number of the server component are acquired (step 2250).

Next, the RPC driver 102 outputs "JIS" which is the output character code set name of the access management component 112v (in the sixth embodiment, the character code used for input / output of the access management component 112v is JIS code). If so, a predetermined value is sent to the SQL conversion means 115 (step 2).
262). Upon receiving this, the SQL conversion means 115
The storage device 1001 uses this as an input character code set name.
It is stored in the storage area 384 (step 2221).

Finally, the RPC driver 102 uses the SQL
Makes RPC connection with the conversion means 115, and SQL_x_RP
The processing of C is requested to the SQL conversion means 115 (step 2202).

Steps 2222 to 2240 are processing contents in the SQL conversion means 115. The requested SQL conversion means 115 first converts the character code of the SQL sentence sent as the RPC parameter into a JIS code, and at the same time, refers to an environment variable that the database driver 122 refers to in order to obtain the character code set name. JIS, which is the character code set after conversion,
The data is stored in the expression format defined by the driver 122 (step 2222).

However, in the sixth embodiment, the input character code set name is "JIS" and conversion is not necessary, so the input character code set name is stored in the environment variable of the database driver 122. This step is performed by the access management component 1 as shown in the second embodiment.
12v is S of a different gateway information processing device 130
When accessing the QL conversion means 115, or as described in the third embodiment, the access management component 1
This is effective when accessing the SQL conversion means 115 from the application software execution means 111 without going through 12v.

Next, the SQL conversion means 115 converts the SQL statement of the standard specification received as the RPC parameter into the SQL specification of the target DBMS (step 222).
3) After that, the SQL statement created by the conversion is sent to the target DBMS, and the SQL from the target DBMS is sent.
A notification of the statement execution result is obtained (step 2224).

The data and the return code obtained as the execution result in step 2224 are converted into SQL conversion means 115.
From the SQL specification of the target DBMS to the standard SQL
The specification is converted (step 2225), and the conversion result is converted into the character code indicated by the input character code set name stored in the storage area 384 in step 2221 (step 2240). Finally, the SQL conversion means 115
Notifies the access management component 112v of the result obtained by the conversion as return data and a return code, and ends the processing of SQL_x_RPC (step 2206).

C. Effects of Sixth Embodiment As described above, in the sixth embodiment, the application software execution unit 111 includes the access management component 112v, the SQL conversion unit 115, and the DBMS_.
It is possible to access the database without being aware of which character code set is used internally by the x121a and x121a. Further, it is not necessary to be aware that the method of designating the character code set name differs for each database driver of each DBMS.

In the sixth embodiment, the character code set that can be handled by the SQL statement analysis unit of the access management component 112v and the SQL statement conversion unit of the SQL conversion means 115 is J.
Although the IS code is used, other character code sets may be used. Further, the RPC driver 102 may be provided with the first and / or second selection means of the second embodiment.

Furthermore, not only the character code set name,
Similar to the input character code set name of the sixth embodiment, the RPC driver of the client information processing apparatus 110 also specifies the language used for error messages and the character code order when sorting the search results of the database. By exchanging data between the 102 and the access management component 112v, it is possible to access the database without being aware of the difference between them.

FIG. 30 shows an example of environment variables for setting the language, character code set, and rearrangement code. The environment variable group 3001 is an example of the environment variable of the application software execution unit 111, the environment variable group 3002 is an example of the environment variable of the access management component 112v, and the environment variable group 3003 is the SQL conversion unit 115 and the DB.
It is an example of the environment variable of the process of MS121a, b.

In the environment variable groups 3001 to 3003,
SQL_LANG is a variable name indicating the type of language used, SQL_CHARACTER is a variable name indicating a character code set to be used, and SQL_COLLATE is a variable name indicating a rearrangement code. In the sixth embodiment, the application software execution unit 111, the access management component 112v, and the SQL conversion unit 115 use Japanese (“JAPANESE”) as the language. Also,
In the application software execution means 111,
Character code set and rearrangement code is "SJIS"
Is. On the other hand, the character code set and rearrangement code of the access management component 112v and the SQL conversion means 115 are "JIS".

In the environment variable group 3003, DB_LA
NG is an environment variable name that is referenced by the database driver 122 and indicates the type of language used (type of language used by the DBMS 121a, b). In addition, the DBMS 121
The character code set used by a and b is the environment variable name DB
It is indicated by the variable of _CHARACTER. further,
The rearrangement code used by the DBMS 121a, 121b is indicated by the variable of the environment variable name DB_COLLATE. In the sixth embodiment, the language used by the DBMS 121a, 121b is Japanese (“JAPANESE”). In addition, the DBMS 121
The character code set and rearrangement code used by a and b are "JIS".

(Embodiment 7) Next, an embodiment will be described in which a function for canceling an access request to a database at a time set by a user is added to the embodiment 1. In FIG. 36,
The structure of the heterogeneous database access system of the seventh embodiment is shown. The heterogeneous database access system of the seventh embodiment has the same configuration as the system of the first embodiment shown in FIG. 1, but in the seventh embodiment, as shown in FIG. 110 and the main storage device 1001 of both the gateway information processing device 130
In addition, storage areas 250 and 251 for holding the SQL timeout time are provided, respectively. Further, the RPC driver 102 of the client information processing apparatus 110 according to the seventh embodiment uses the time-out counter 252 for clocking.
Equipped with. Further, the RPC driver 102 of the gateway information processing device 130 also includes a time-out counter 253 for measuring time.

A. Flow of processing of SQL_RPC FIG. 25 shows processing of SQL_RPC in the seventh embodiment. In the seventh embodiment, similarly to the first embodiment, the SQL_RPC issued from the application software 111 on the client information processing device 110 is an access management component on the gateway information processing device 130 by the RPC driver 102 of the client information processing device 110. 112v is notified and processed by the access management component 112v.

However, unlike the first embodiment, in the seventh embodiment, the RPC driver 102 of the client information processing apparatus 110 requests the access management component 112v to process the SQL_RPC by using the RPC, and then is determined in advance. If a response is not received even after the SQL timeout time elapses, the processing is aborted and an error occurs. In the seventh embodiment, the SQL timeout time is the main memory 1 of the client information processing apparatus 110.
It is stored and held in advance in the storage area 250 of 001.

First, the application software 1
The RPC driver 102 of the client information processing apparatus 110 that receives the SQL_RPC issued by the
It is judged whether or not it is a connection statement to the MS (step 256).
1) If it is a connection statement, execute steps 2550 and 2562 and then step 2553,
If the sentence is other than the connection sentence, step 255 is directly executed.
Execute 3.

At step 2550, the RPC driver 1
An access management component 11 is a server 02 that accesses the name server 151 on the name server information processing device 150 and processes the SQL_RPC to be processed.
Obtain the 2v physical location or network address and port number of the server component. Then R
In step 2562, the PC driver 102 stores the storage area 250 of the storage device on the client information processing apparatus 110.
The SQL timeout time stored in the above is sent to the access management component 112v. The access management component 112v that has received the SQL timeout time stores the received SQL timeout time in the storage area 251 of the gateway information processing device 130 (step 2501).

Next, the RPC driver 102 activates the RPC execution thread (step 2553). Here, a thread is a processing unit that further divides processing within a process and performs parallel processing by time division. The activated RPC execution thread makes an RPC connection with the access management component 112v, and requests the access management component 112v for the processing of the SQL_RPC (step 2580).

Steps 2501-2504 are processes in the access management component 112v. Example 1
4, when the access management component 112v of the seventh embodiment receives the processing request, it analyzes the SQL statement (step 2502) and SQL_x.
_RPC issuance (step 2503) and other processing is performed, and the processing result is the RPC that activated the requesting RPC execution thread.
Notify the driver 102 (parent thread) to request R
After notifying the PC execution thread of the end, the processing of the RPC is ended (step 2504).

RPC requested to be processed in step 2580
The execution thread is the access management component 112v.
The thread is in a waiting state until the end signal (step 2504) is received, and when the end notification is received, the thread is ended (step 2585).

On the other hand, the parent thread which started the RPC execution thread in step 2553 is the timeout counter 2
After initializing 52 (step 2554), the timeout counter 252 is counted up (step 255).
5), the value held by the timeout counter 252 is S
It is checked whether the value held in the QL timeout time storage area 250 is exceeded (step 2556). If not, it is further checked whether the RPC execution thread has already ended (step 255).
7).

If the RPC execution thread has not finished yet, the parent thread returns the processing to step 2555,
The timeout counter is counted up and the elapsed time is checked repeatedly. In the seventh embodiment, when the RPC execution thread is activated, predetermined identification information is stored in the main storage device 1001 of the client information processing apparatus 110, and the RPC execution thread is terminated at the end (step 2585). , The identification information is deleted. Step two
The termination check of the RPC execution thread in 557 is
This is performed by checking whether the identification information is held in the storage device of the client information processing device 110.

If the result of the time-out check in step 2556 is that there is a time-out, the parent thread stores the error code in a predetermined area (step 2559) and terminates the SQL_RPC processing (step 2560). . Note that when setting the error code (step 2559), in the seventh embodiment, the parent thread disconnects the RPC execution thread and the access management component 112v and terminates the RPC execution thread.

If it is determined as a result of the RPC execution thread end check in step 2557 that it has ended, the execution result is stored in a predetermined area (step 2558) and the SQL_RPC processing ends (step). 2560).

B. Processing of SQL_x_RPC (step 2503) FIG. 26 shows processing of SQL_x_RPC issued by the access management component 112v in the seventh embodiment. In the seventh embodiment, the access management component 11
SQL conversion component 11 requested by 2v
Regarding the processing of SQL_RPC of 5, if the processing is not performed within a predetermined time, the processing is aborted and an error occurs.

The procedure of the process is the same as that of the above-mentioned SQL_RPC process, but in the process of SQL_x_RPC, the value stored in the storage area 251 in the above step 2501 (shown in FIG. 25) is the SQL timeout time. Used as.

First, the access management component 112
The RPC driver 102 of the gateway information processing device 130 that has received the SQL_x_RPC issued by v
It is judged whether or not it is a connection statement to BMS (step 266).
1) If it is a connection statement, step 2650 is executed and then step 2653 is executed. If it is a statement other than a connection statement, step 2653 is directly executed.

At step 2650, the RPC driver 1
02 accesses the name server 151 on the name server information processing device 150, and processes SQL_x_RP to be processed.
The physical location (network address and port number) of the SQL conversion means 115 that processes C is acquired.

Next, the RPC driver 102 activates the RPC execution thread (step 2653). The started RPC execution thread is sent to the SQL conversion unit 115 and the RP.
The C connection is performed, and the processing of SQL_x_RPC is requested to the SQL conversion means 115 (step 2680).

Steps 2602 to 2604 are the processing of the SQL conversion means 115. SQL conversion means 115,
When the processing request is received, the SQL sentence is analyzed (step 26
02), accesses the DBMS, receives a response (step 2603), notifies the processing result to the RPC driver 102 (parent thread) that started the RPC execution thread of the request source, and terminates the RPC execution thread of the request source. After notifying, the processing is ended (step 2604).

RPC requested to be processed in step 2680
The execution thread is in a waiting state until it receives the end signal (step 2604) of the SQL conversion means 115, and when it receives the end notification, it terminates the thread (step 2685).

On the other hand, the parent thread which started the RPC execution thread in step 2653 is the timeout counter 2
After initializing 53 (step 2654), the time-out counter 253 is incremented (step 265).
5), the value held by the timeout counter 253 is S
It is checked whether or not the value held in the QL timeout time storage area 251 is exceeded (step 2656), and if not exceeded, it is further checked whether or not the RPC execution thread has already ended (step 265).
7).

If the RPC execution thread has not finished yet, the parent thread returns the processing to step 2655,
The timeout counter is counted up and the elapsed time is checked repeatedly. When the RPC execution thread is activated, predetermined identification information is stored in the main storage device 1001 of the gateway information processing device 130,
When the RPC execution thread ends (step 2685)
Then, the identification information is deleted. The end check of the RPC execution thread in step 2657 is performed by checking whether the identification information is held in the storage device.

If the result of the time-out check in step 2656 is that the time-out has been determined, the parent thread stores the error code in a predetermined area (step 2659) and terminates the SQL_RPC processing (step 2660). . In addition, when the error code is set (step 2659), in the seventh embodiment, the parent thread disconnects the RPC execution thread from the DBMS,
Terminate the RPC execution thread.

If it is determined as a result of the RPC execution thread end check in step 2657 that it has ended, the execution result is stored in a predetermined area (step 2658) and the SQL_x_RPC processing ends (step). 2660).

C. Effects of Seventh Embodiment As described above, according to the seventh embodiment, the timeout value is changed from the application software 111 to the access management component 112v and the SQL conversion means 11.
5 to the database prior to the connection to the database, the RPC process in each component can be terminated within the SQL timeout time set by the application software 111.

Further, according to the seventh embodiment, even when the application software executing means accesses the database via the gateway, the processing at the time of database access set by the process in which the application software executing means operates. The termination time can be reflected in the database access processing termination time that the gateway refers to when accessing the database, so there is no need to set the termination time individually on the application software execution means side and the gateway side. There is.

Note that the timeout check may be performed by the same method when the SQL conversion means 115 accesses the DBMS. In this case, the RPC driver 102 executes step 2650 and then step 2653.
Before execution, the SQL time-out time held in the storage area 251 of the storage device of the gateway information processing device 130 is sent to the SQL conversion means 115, and the SQL time-out means 1 receives the SQL time-out time.
15 stores the received SQL timeout time in the storage area secured as a storage area for the SQL timeout time for SQL conversion means in the gateway information processing device 130. By doing this, when the SQL conversion means 115 accesses the DBMS, the stored S
By referring to the SQL timeout time for QL conversion means, and if the processing time exceeds that time, an error is generated.
For the DBMS access by the SQL conversion unit 115, a time limit can be set for the processing.

By the way, the SQL_RPC issued from the application software 111 is the access management component 112v, SQ as shown in FIG.
The processes in the L conversion means 115 and the DBMS 121 are executed in a nested form. Therefore, when the processing termination due to the time-out in each component occurs at the same time, the application software 111 cannot correctly recognize in which component the processing time exceeds the timeout value.

To solve this, the S received by the access management component 112v in step 2501.
The time obtained by subtracting a fixed time from the QL timeout time may be stored as the SQL timeout time used by the access management component 112v.

As a result, the component closer to the application software 111 than the component (access management component or SQL conversion means) that has detected the timeout error has not reached the SQL timeout time at the time of the detection. Since the processing has not been aborted yet, the error code from the component that detected the timeout error can be correctly transmitted to the application software 111. This way, if the process is aborted,
The location where the processing time is exceeded can be easily identified.

The RPC driver 102 according to the seventh embodiment is used.
In addition, the first and / or second selection means of the second embodiment may be provided. Further, each information processing device may be provided with an external storage device, and the storage areas provided in the main storage device 1001 described above may be provided in this external storage device.

(Embodiment 8) Next, an embodiment for monitoring a failure of a server and a client will be described. Example 8
Figure 3 shows the configuration of the heterogeneous database access system
7 shows. Heterogeneous database access of the eighth embodiment
The system has a configuration similar to that of the seventh embodiment. However, in the eighth embodiment, as shown in FIG. 37, the main storage device 1001 of the client information processing device 110 is SQL
In addition to the timeout time storage area 250, storage areas 371 and 372 for holding the server check RPC timeout time and the server check RPC interval time, respectively, are further provided, and similarly, the main part of the gateway information processing device 130 is provided. The storage device 1001 is SQ
In addition to the L timeout time storage area 251,
Storage areas 373 and 374 are provided for holding the server check RPC timeout time and the server check RPC interval time, respectively. In addition to the timeout counter 252, the RPC driver 102 of the client information processing apparatus 110 according to the eighth embodiment further includes an interval timer 375 for counting the server check RPC issuance interval, and the gateway information processing apparatus 130. Access management component 1
12v has a client check timer 376 for measuring the timing of checking the operation of the client,
Further prepare.

The RPC driver 102 according to the eighth embodiment.
In addition, the first and / or second selection means of the second embodiment may be provided. Further, each information processing device may be provided with an external storage device, and the storage areas provided in the main storage device 1001 described above may be provided in this external storage device.

A. Flow of SQL_RPC Processing FIG. 27 shows the processing of SQL_RPC in the eighth embodiment. R of the client information processing apparatus 110 according to the eighth embodiment
Upon receiving the SQL_RPC issued from the application software 111, the PC driver 102 first determines whether or not the SQL_RPC is a connection statement to the DBMS (step 2751), and if it is a connection statement, steps 2752-. After executing 2754, control is transferred to step 2790, and if it is not a connection statement, control is directly transferred to step 2790.

At step 2752, the RPC driver 1
02 acquires the physical location of the access management component 112v, as in the seventh embodiment. In step 2753, the RPC driver 102 uses the SQ described in the seventh embodiment.
In addition to the L timeout time, the server check RPC timeout time previously held in the storage area 371 and the server check RPC interval time previously held in the storage area 372 are notified to the access management component 112v. Next, the client RPC driver 102 activates the server checking thread (step 2754).

The access management component 112v which has received the notification in step 2753 sets the SQL timeout time, the server check RPC timeout time, and the server check RPC interval time, respectively.
The data is stored in the storage areas 251, 273, 274 (step 2701). Also, the access management component 112
v activates the client check thread (step 2702).

On the other hand, the RPC driver 102 of the client information processing apparatus 110, after initializing the interval timer 375 (step 2790), checks whether the SQL statement is a disconnect statement for disconnecting the connection to the database (step 2760). If it is a disconnection statement, the server checking thread started in step 2754 is terminated (step 2761).

Next, the RPC driver 102 activates the RPC execution thread as in the seventh embodiment (step 2).
762). The RPC execution thread started here issues an RPC to the access management component 112v and requests its processing (step 2780), and waits for a processing end notification of the access management component 112v. R on the side of the access management component 112v requested to process
The PC server initializes the client check timer 376 (step 2703) and analyzes the SQL statement (step 2502).

It should be noted that the continuation of the processing described above (step 2
554 to 2560, step 2585, step 250
2 to 2504) are the same as the processing illustrated in FIG. 25 in the above-described seventh embodiment.

B. Processing of Server Check Thread FIG. 28 shows processing of the server check thread that is started in step 2754 and ends in step 2761 described above.

When the server check thread is activated, first, the interval timer 375 is initialized (step 2801), the interval timer 375 counts up (step 2802), and the value held by the interval timer 375 is stored. By repeating the check (step 2803) as to whether or not the server check RPC interval time stored in the area 372 has been reached, the process waits until the value of the interval timer 375 reaches the predetermined server check RPC interval time.

When the server check RPC interval time is reached, the server check thread is returned to SQL_
It is checked whether or not the RPC processing is being executed (that is, whether or not the RPC execution thread is terminated in this embodiment) (step 2890). If it is being executed, the processing is returned to step 2801. . If it is not running, the server check thread activates the server check RPC execution thread (step 280).
4).

The activated server check RPC execution thread issues a server check RPC to the access management component 112v and waits for a response (step 2850). In addition, this server check RPC is
Access management component 112, which is an RPC server
It is an RPC of a simple predetermined instruction for checking whether v has no fault. RP for server check
When the processing by the access management component 112v of C is completed, the RPC execution thread for server check is
The server check RPC end message is set and the thread is ended (step 2851).

On the other hand, the parent thread which started the server check RPC execution thread in step 2804 initializes the timeout counter 252 (step 280).
5), timeout counter count-up in step 2806, timeout check in step 2807,
The end check of the server check RPC execution thread in step 2808 is performed for a predetermined time (server check RP
It is repeatedly executed until (C timeout time) elapses or the server check RPC execution thread ends. The timeout check in step 2807 is determined by whether or not the value of the timeout counter 252 has reached the server check RPC timeout time held in the storage area 371. Also, the RPC end check in step 2808 is performed in step 285.
It is determined whether the end message set in 1 is already set.

When the predetermined time has passed as a result of the time-out check in step 2807, the server checking thread sets an error code in step 2820 (step 2820) and terminates the thread (step 2821). Also, as a result of the server check RPC end check in step 2808, the server check RP
If the C execution thread has ended, the server checking thread returns the processing to step 2801.

In this way, from the time when the DBMS is connected to the time when the DBMS is disconnected, at a predetermined fixed time (RPC interval time for server check),
You can check the normal operation of the server.

In the eighth embodiment, the server timer RPC is periodically issued using the interval timer 375. However, in step 2890, SQL_RPC is issued.
If there is a conflict between the execution of the above process and the server check RPC, the issuance of the server check RPC is canceled and the interval timer 375 is initialized again (step 2801).
Then, the timing is re-executed.

Further, the interval timer 375 is SQ
Each time L_RPC is received by the RPC driver 102 of the client, it is initialized in step 2790 (FIG. 27). Therefore, SQL_RPC and server check R
SQL_RPC within the server check RPC interval time from the time when the last one of the PCs was issued.
Is issued, an RPC for server check is issued. This makes it possible to minimize the number of server check RPCs issued.

C. Processing of Client Check Thread Next, the processing contents of the client check thread (client check processing execution means) started in step 2702 (FIG. 27) will be described with reference to FIG.

When the client check thread is activated, it first initializes the client check timer 376 (step 3301) and checks whether SQL_RPC is being processed (step 3302). If not, the client check timer 376 is checked. Count up 376 (step 3303).

Next, the client check thread checks whether the value held by the client check timer 376 has reached the timeout time (step 3
304), if it is determined that it has not reached step 3
The process is returned to 302. Here, the timeout time is a time set based on the value held in the server check RPC interval time storage area 374. Considering the accuracy of the interval timer, the delay in the communication path, and the like, it is appropriate that this time is between 1.2 and 2 times the RPC interval time for server check.

If it is determined in step 3304 that the time-out period has been reached, the client checking thread gives an error notification (step 330).
5) Perform thread termination processing (step 330)
6).

D. Processing on Server Side of Server Checking RPC FIG. 34 shows processing contents on the server side of the server checking RPC. Access management component 1112v
When receiving the server check RPC issued in step 2850, initializes the client check timer 376 (step 3401), gives an end notification, and ends the process (step 3490).

The initialization of the client check timer 376 (step 3401) is also performed when the SQL_RPC is accepted in the SQL_RPC processing as already shown in step 2703 of FIG. Therefore, the timeout check by the client check timer 376 is monitoring whether the client issues either the server check RPC or SQL_RPC within the timeout time.

E. Access management component 112v
And the processing performed when the SQL conversion means 115 mutually perform failure check In the above description, the example in which the RPC driver 102 of the client and the access management component 112v mutually perform failure check has been described. Even when the SQL conversion means 115 and the SQL conversion means 115 mutually perform a failure check, they can be realized in exactly the same manner as shown in FIG. The flow of processing in this case will be described below.

First, the access management component 112
Upon receiving the SQL_RPC notified from the RPC driver 102 of the client, v receives the SQL_RPC.
Is a connection statement to the DBMS (step 3
251), and if it is a connection statement, steps 3252 to 3252.
After executing 3254, control is transferred to step 3290, and if it is not a connection statement, control is directly transferred to step 3290.

At step 3252, the access management component 112v acquires the physical position of the SQL conversion means 115. In step 3253, the access management component 112v causes the SQL timeout time held in the storage area 251, the server check RPC timeout time held in the storage area 373, and the server check RPC interval time held in the storage area 374. And the SQL conversion means 115. Next, the access management component 112v activates the server check thread (step 3254).

SQ notified in step 3253
The L conversion means 115 stores the SQL timeout time, the server check RPC timeout time, and the server check RPC interval time in a storage area (not shown) (step 3201). Also, SQL
The conversion unit 115 activates a client check thread (access management unit check processing execution unit) (step 3202).

On the other hand, the access management component 112
After initializing the interval timer 375 (step 3290), v checks whether the SQL statement is a disconnect statement for disconnecting the connection to the database (step 326).
0), if it is a disconnection statement, the server check thread started in step 3254 is terminated (step 3261).

Next, the access management component 11
2v starts the RPC execution thread (step 32).
62). The RPC execution thread started here is SQ
It issues an RPC to the L conversion means 115, requests its processing (step 3280), and waits for a processing end notification. The SQL conversion means 115, which has been requested to process, initializes the client check timer 376 (step 3203), and SQ
The L sentence is analyzed (step 2502).

The continuation of the processing described above (step 2
554 to 2560, step 2585, step 250
2 to 2504) are the same as the processing illustrated in FIG. 25 in the seventh embodiment.

F. Setting Example of Each Time FIG. 31 shows a setting example of the SQL timeout time, the server check RPC timeout time, and the server check RPC interval time in the above embodiment. In the eighth embodiment, as shown in FIG. 31, the SQL timeout time is SQL_TIMEOUT, R for server check.
PC timeout time is SERV_TIMEOUT, server check RPC interval time is SERV_C
It is stored and defined in an environment variable storage area named HKINT. Although these set values are environment variables in the eighth embodiment, the set values are not limited to these and may be anything as long as they can be stored. In the example shown in FIG. 31, the unit of each time is all seconds.

The set value group 3101 is an application
Software execution means 111 and client RPC
It is an environment variable of the process of the driver 102, and is a user or application software execution means 11
Set by 1. In this setting 3101, the SQL timeout time is 3600 seconds, the server check RPC timeout time is 10 seconds, and the server check RPC interval time is 600 seconds.

The set value group 3102 is an environment variable of the process of the access management component 112v and is used when connecting to the database.
v sets the value of the set value group 3101 described above to the RP of the client.
It is received from the C driver 102 and set. With this setting 3102, the SQL timeout time is 350.
0 seconds, server check RPC timeout time is 10
Seconds, server check RPC interval time is 600
Seconds. Here, the SQL timeout time is a value obtained by subtracting 100 from the received value.

The set value group 3103 is the SQL conversion means 11
These are environment variables of the process No. 5 and are set by the SQL conversion means 115 upon receiving a value from the access management component 112v from the access management component 112v when the database is connected. In this setting 3103, the SQL timeout time is 3400 seconds, the server check RPC timeout time is 10 seconds, and the server check RPC interval time is 600 seconds. Here again, the SQL timeout time is the value obtained by subtracting 100 from the received value.

As described above, in the eighth embodiment, the server check RPC is used and the server failure is detected periodically at the set interval time.
A server failure can be recognized before executing RPC for database access. Further, the server side monitors whether or not the server check RPC is issued periodically, so that the failure can be detected on the client side.

In the eighth embodiment, the processing termination time at the time of database access can be set for each process of the application software executing means, so that the processing termination time can be set appropriately according to the application. Furthermore, according to the eighth embodiment, it is possible to detect a failure of a component on the gateway information processing device or a DBMS before the SQL statement is issued, and useless SQL statement issuance or
It is possible to prevent the occurrence of a failure detection waiting time. Further, according to the present embodiment, the failure of the component on the side requesting access, that is, the failure of the component on the client side (in the case of the access management component 112v) or the failure of the access management component 112v (SQ
(In the case of the L conversion means 115) can be detected. As a result, the process corresponding to the failed component can be abnormally terminated, and the resources of the gateway information processing device, such as the CPU 1000 and the main storage device 1001, can be effectively used by other processes.

(Effects of the First to Eighth Embodiments) In the first to eighth embodiments described above, two kinds of DBs having different SQL specifications are used.
I explained the case of mixed MS, but how many kinds of DB
MSs may be mixed, and not only SQL specifications but also communication protocols may be different. Also, an example in which the information processing apparatuses are connected by a LAN has been shown.
WAN (Wide Area N) such as telephone lines
The present invention can also be applied to a connection based on the network or a connection environment using both LAN and WAN. Further, the RPC in the above-described embodiment is an interface mechanism capable of requesting processing and receiving the processing result regardless of between programs in the same information processing apparatus or between programs on another information processing apparatus. Anything can be used if it exists. In addition, selection of the gateway information processing device, timeout monitoring, etc. are not limited to the database access system,
It can also be applied to other distributed processing systems using a PC. The above Examples 1 to 8 can be arbitrarily combined.

In addition, one SQL conversion means 115 is
It can handle database access for multiple DBMSs with the same SQL specification. Therefore, it is not necessary to prepare the SQL conversion means 115 for each operating DBMS, and at least the number of SQL conversion means 115 corresponding to the type of operating DBMS can be introduced. Cost can be reduced.

[0236]

According to the present invention, the load can be distributed to a plurality of gateway information processing devices. Further, according to the present invention, it is possible to reduce the overhead of passing through the gateway information processing device. Further, according to the present invention, application software using non-standard SQL can be used to convert non-standard SQL using D
BMS can be accessed.

Also, according to the present invention, a free character code set can be used for each application software of the client. Furthermore, according to the present invention, the DB from the application software execution means is
A free character code set can be used for the connection unit to the MS.

Further, according to the present invention, at the time of accessing the database, if the time arbitrarily set for each application software of the client elapses, the processing can be terminated. Further according to the invention,
Components and DBM on the gateway information processing device
The failure of S can be detected before the SQL statement is issued, and the failure of the connected client can be detected on the side of the gateway information processing device.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a database access system according to a first embodiment.

FIG. 2 is a configuration diagram showing a configuration example of a conventional database access access system.

FIG. 3 is a configuration diagram showing another configuration example of a conventional database access access system.

FIG. 4 is a flowchart illustrating RPC processing issued from the client information processing apparatus to the access management component according to the first embodiment.

FIG. 5 is a flowchart showing a process of RPC issued from the access management component to the SQL conversion means in the first embodiment.

FIG. 6 is a configuration diagram of a database access system according to a third embodiment.

FIG. 7 is a flowchart showing SQL processing in a client according to the third embodiment.

FIG. 8 is a configuration diagram of a database access system according to a fourth embodiment.

FIG. 9 is a configuration diagram of a database access system according to a second embodiment.

FIG. 10 is an explanatory diagram showing an operation of the gateway information processing device 130 according to the first embodiment.

FIG. 11 is a configuration diagram of a database access system according to a fifth embodiment.

FIG. 12 is a flowchart showing processing when a server component is selected using random numbers in the second embodiment.

FIG. 13 is a diagram showing an example of contents of a priority order table prepared for selecting a server component in the second embodiment.

FIG. 14 is a flowchart showing processing when a server component is selected according to a load state in the second embodiment.

FIG. 15 is a flowchart showing processing when a server component is selected according to response time in the second embodiment.

FIG. 16 is a flowchart showing processing when a server component is selected using broadcast RPC in the second embodiment.

FIG. 17 is an explanatory diagram illustrating an example of a server information table according to the second embodiment.

FIG. 18 is a diagram showing another configuration of the system using the first embodiment.

FIG. 19 is a configuration diagram showing another configuration of the database access system according to the fifth embodiment.

FIG. 20 is a flowchart illustrating processing for delaying a response to a processing request by broadcast according to a load state of an information processing device in which a server component operates in the second embodiment.

FIG. 21 is a flowchart showing RPC processing issued from the client information processing apparatus to the access management component in the sixth embodiment.

FIG. 22 is a flowchart showing a process of RPC issued from the access management component to the SQL conversion means in the sixth embodiment.

FIG. 23 is a diagram showing an example of an SQL statement processed by the access management component 112v in the first embodiment.

FIG. 24 is a diagram showing an example of an SQL sentence converted by the SQL conversion means in the first embodiment.

FIG. 25 is a flowchart showing RPC processing issued from the client information processing device to the access management component in the seventh embodiment.

FIG. 26 is a flowchart showing a process of RPC issued from the access management component to the SQL conversion means in the seventh embodiment.

FIG. 27 is a flowchart showing the RPC processing issued from the client information processing device to the access management component in the eighth embodiment.

FIG. 28 is a flowchart illustrating the processing of a server check thread that performs server failure monitoring processing according to the eighth embodiment.

FIG. 29 is an explanatory diagram showing a sequence of RPCs issued between components according to the seventh embodiment.

FIG. 30 is an explanatory diagram of a character code setting example according to the sixth embodiment.

FIG. 31 is an explanatory diagram showing an example of time setting regarding failure detection in the seventh and eighth embodiments.

FIG. 32 is an RP issued from the access management component to the SQL conversion_X component in the eighth embodiment.
It is a flowchart which shows the process of C.

FIG. 33 is a flowchart illustrating processing of a client check thread according to the eighth embodiment.

FIG. 34 is a flowchart showing processing on the server side of the server checking RPC in the eighth embodiment.

FIG. 35 is an explanatory diagram showing an example of a server information table according to the first embodiment.

FIG. 36 is a configuration diagram showing a configuration of a database access system according to a seventh embodiment.

FIG. 37 is a configuration diagram showing a configuration of a database access system according to an eighth embodiment.

FIG. 38 is a configuration diagram showing a configuration of a database access system according to a sixth embodiment.

FIG. 39 is a hardware configuration diagram of the database access system according to the first embodiment.

[Explanation of symbols]

100 ... LAN, 102 ... RPC driver, 110 ... Client information processing device, 111 ... Application
Software execution means, 112 ... Access management component, 115 ... SQL conversion means, 120 ... Server information processing device, 121 ... DBMS, 122 ... Database driver, 123 ... LAN driver, 124 ... External storage device, 130 ... Gateway information processing device, Reference numeral 150 ... Name server information processing device, 151 ... Name server component, 1300 ... Server priority order table, 170
0 ... Server information table.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nao Hashimoto 5030 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Within the software development division of Hitachi, Ltd. (72) Eisaku Nishiyama 5030 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd. Software Development Division

Claims (24)

[Claims] 1. Accessing a plurality of server information processing apparatuses equipped with a database management system that receives an access request to a database in a database access language and returns a response, and the database management system connected to the server information processing apparatuses. A database access system having one or more client information processing devices equipped with application software execution means for issuing the target request, comprising: a gateway information processing device that receives the access request and sends it to the database management system. The gateway information processing device receives the access request, converts it into a request in a different database access language, and sends it to the database management system. The client information processing apparatus includes: an access management unit that receives the access request and sends the access request to the database access language conversion unit; and the client information processing apparatus includes a character code of a character code used by the application software execution unit to issue the request. A means for notifying the set identification information to the access management means is provided, and the access management means, before sending to the database access language conversion means,
Means for converting the received character code of the request into a character code of a predetermined character code set, and means for converting a response notified to the client information processing device into a character code of the notified character code set A database access system comprising: 2. Accessing a plurality of server information processing apparatuses equipped with a database management system which receives an access request to a database in a database access language and returns a response, and the database management system connected to the server information processing apparatuses. A database access system having one or more client information processing devices equipped with application software execution means for issuing the target request, comprising: a gateway information processing device that receives the access request and sends it to the database management system. The gateway information processing device receives the access request, converts it into a request in a different database access language, and sends it to the database management system. Access management means for receiving the access request and sending it to the database access language conversion means, the access management means notifying the database access language conversion means of predetermined character code set identification information. Means for converting the character code of the received request into a predetermined character code, and a response for notifying the access management means of the notified character code. A database access system comprising means for converting a character code of a set. 3. Accessing a plurality of server information processing apparatuses equipped with a database management system which receives an access request to a database in a database access language and returns a response, and the database management system connected to the server information processing apparatuses. A database access system having one or more client information processing devices equipped with application software execution means for issuing the target request, comprising: a gateway information processing device that receives the access request and sends it to the database management system. The gateway information processing device receives the access request, converts it into a request in a different database access language, and sends it to the database management system. The client information processing apparatus secures a connection with the access management unit and issues the request when the client information processing device issues the request and receives the access request and sends it to the database access language conversion unit. Means for sending to the access management means, and no response even if a predetermined time has passed,
Database access characterized by means for disconnecting the connection and causing an error in the processing of the request.
system. 4. Accessing a plurality of server information processing apparatuses equipped with a database management system that receives an access request to a database in a database access language and returns a response, and the database management system connected to the server information processing apparatuses. A database access system having one or more client information processing devices equipped with application software execution means for issuing the target request, comprising: a gateway information processing device that receives the access request and sends it to the database management system. The gateway information processing device receives the access request, converts it into a request in a different database access language, and sends it to the database management system. And an access management unit that receives the access request and sends the access request to the database access language conversion unit. When the access management unit receives the request, the access management unit secures a connection with the database access language conversion unit. Means for sending a request to the database access language conversion means, and no response even if a predetermined time has passed,
A database access system, comprising means for disconnecting the connection and notifying the client information processing device of an error in the processing of the request. 5. Accessing a plurality of server information processing apparatuses equipped with a database management system which receives an access request to a database in a database access language and returns a response, and the database management system connected to the server information processing apparatuses. A database access system having one or more client information processing devices equipped with application software execution means for issuing the target request, comprising: a gateway information processing device that receives the access request and sends it to the database management system. The gateway information processing device receives the access request, converts it into a request in a different database access language, and sends it to the database management system. And an access management unit that receives the access request and sends the access request to the database access language conversion unit. When the database access language conversion unit receives the request, the connection management unit secures a connection with the database management system unit, Means for sending the request to the database management system, and no response even if a predetermined time has passed,
A database access system, comprising: means for disconnecting the connection and notifying an access management means of an error in processing the request. 6. The access management means according to claim 3, upon receiving the request, securing the connection with the database access language conversion means and sending the request to the database access language conversion means. , If there is no response after a predetermined time,
A database access system, comprising means for disconnecting the connection and notifying the client information processing device of an error in the processing of the request. 7. The database access language conversion means according to claim 6, upon receiving the request, securing the connection with the database management system means and sending the request to the database management system. If there is no response even after the stipulated time has passed,
A database access system, comprising: means for disconnecting the connection and notifying an access management means of an error in processing the request. 8. The database access language conversion means according to claim 4, when receiving the request, securing the connection with the database management system means and sending the request to the database management system in advance. If there is no response even after the stipulated time has passed,
A database access system, comprising: means for disconnecting the connection and notifying an access management means of an error in processing the request. 9. The time set in advance in the client information processing device, the time set in the access management unit, and the time set in the database access language conversion unit according to claim 7. , Database access system characterized by being short in this order. 10. The client information processing device according to claim 6, further comprising means for notifying the access management means of a predetermined time of the client information processing device, wherein the access management means comprises: A database access system, wherein the notified time is used as a predetermined time for the access management means. 11. The database access language conversion according to claim 7, further comprising means for notifying the database access language conversion means of a predetermined time of the access management means. The database access system is characterized in that the means uses the notified time as a predetermined time for the database access language conversion means. 12. The database access language conversion according to claim 8, further comprising means for notifying the database access language conversion means of a predetermined time of the access management means. The database access system is characterized in that the means uses the notified time as a predetermined time for the database access language conversion means. 13. The access management means according to claim 10, further comprising means for notifying the database access language conversion means of a predetermined time of the access management means. The database access system is characterized in that the means uses the notified time as a predetermined time for the database access language conversion means. 14. Accessing a plurality of server information processing apparatuses equipped with a database management system which receives an access request to a database in a database access language and returns a response, and the database management system connected to the server information processing apparatuses. A database access system having one or more client information processing devices equipped with application software execution means for issuing the target request, comprising: a gateway information processing device that receives the access request and sends it to the database management system. The gateway information processing device receives the access request, converts it into a request in a different database access language, and sends it to the database management system. The client information processing apparatus includes an access management unit that receives the access request and sends the access request to the database / access language conversion unit, and the client information processing apparatus transmits the predetermined access request for failure check for a predetermined time. The failure check means for issuing each time and sending to the gateway information processing device, and the failure for notifying the application / software execution means of an error if the response to the failure check access request is not within a predetermined time. A database access system having a notification means. 15. Accessing a plurality of server information processing apparatuses equipped with a database management system which receives an access request to a database in a database access language and returns a response, and the database management system connected to the server information processing apparatuses. A database access system having one or more client information processing devices equipped with application software execution means for issuing the target request, comprising: a gateway information processing device that receives the access request and sends it to the database management system. The gateway information processing device receives the access request, converts it into a request in a different database access language, and sends it to the database management system. And an access management unit that receives the access request and sends the access request to the database / access language conversion unit, and the access management unit issues the access request for failure check every predetermined time. A failure check means for sending to the database access language conversion means, and failure notification means for notifying the client information processing device of an error if the response to the failure check access request is not within a predetermined time. A database access system characterized by having. 16. A plurality of server information processing devices, each of which is provided with a database management system that receives an access request to a database in a database access language and returns a response, and accesses the database management system connected to the server information processing device. A database access system having one or more client information processing devices equipped with application software execution means for issuing the target request, comprising: a gateway information processing device that receives the access request and sends it to the database management system. The gateway information processing device receives the access request, converts it into a request in a different database access language, and sends it to the database management system. The database access language conversion means receives the access request and sends it to the database access language conversion means, and the database access language conversion means receives the access request for failure check every predetermined time. A failure check means for issuing and sending to the database management system, and a failure notification means for notifying the access management means of an error if the response to the failure check access request is not within a predetermined time. A database access system characterized by. 17. The issue of the fault check access request of the fault check means of the client information processing apparatus according to claim 14, wherein the connection is disconnected after receiving an access request for instructing a connection to a database management system. A database access system characterized in that it is carried out until an access request for instructing is received. 18. The issue of the fault check access request of the fault check unit of the access management unit according to claim 15, wherein the connection is disconnected after the access request for instructing the connection to the database management system is accepted. A database access system characterized in that it is carried out until an access request to be instructed is received. 19. The access request for failure check of the failure check means of the database access language conversion means according to claim 16, when the access request for instructing connection to the database management system is issued, A database access system, which is performed until an access request for instructing disconnection is issued. 20. Accessing a plurality of server information processing devices equipped with a database management system that receives an access request to a database in a database access language and returns a response, and the database management system connected to the server information processing devices. In a method of controlling a database access system having one or more client information processing devices equipped with application software execution means for issuing the target request, the character used by the client information processing device for issuing the request. The step of notifying the character code set identification information of the code, the step of accepting the access request, the step of converting the character code of the received request into a character code of a predetermined character code set, and the character code The converted access request is converted into a request in a different database access language and sent to the database management system, and a response to notify the client information processing device includes a character code of the notified character code set. The method of controlling a database access system, comprising: 21. Accessing a plurality of server information processing apparatuses equipped with a database management system that receives an access request to a database in a database access language and returns a response, and the database management system connected to the server information processing apparatus. In a method of controlling a database access system having one or more client information processing devices including application software execution means for issuing the target request, in the step of receiving the access request, and when receiving the request, Securing a connection with the database access language conversion means and sending the request to the database access language conversion means; and converting the request into a request in a different database access language and sending it to the database management system. A step, when no response is received after a predetermined time is,
And a step of notifying the client information processing device of an error in the processing of the request, the method of controlling the database access system. 22. Accessing a plurality of server information processing devices equipped with a database management system that receives an access request to a database in a database access language and returns a response, and the database management system connected to the server information processing device. In a method of controlling a database access system having one or more client information processing devices having application software execution means for issuing the target request, a request receiving step for receiving the access request, and the received access request Is converted into a request in a different database access language, and the request processing step for sending to the database management system and the access request for failure check are issued every time a predetermined time has passed, A failure detection step of sending to the database management system, and a failure notification step of notifying an error to the access management means if the response to the failure check access request is not within a predetermined time. How to control the Database Access System. 23. The access management means according to claim 17, wherein the access request to the database in the database access language issued by the client information processing apparatus and the failure check access request are issued. A means for executing client check processing that inspects whether it has been received within a predetermined time,
Provided for each client information processing device to be inspected, if neither the access request to the database in the database access language nor the access request for failure check is accepted within a predetermined time, the client check A database access system characterized by abnormally terminating processing. 24. The database access language conversion means according to claim 18, wherein the access request to the database in the database access language and the failure check access request are issued within a predetermined time. Each access management means to be inspected has an access management means check processing execution means for inspecting whether or not it has been accepted, and both the access request to the database in the database access language and the failure check access request, If the access is not accepted within a predetermined time, the access control means check process is abnormally terminated.
system.