Abstract:
A method, apparatus and program storage device for enabling SQL statement access to remote system specific data and functions is provided. A method is developed to utilize wrapper stored procedures and the table formatted output of native commands in order to access the output via direct SQL statements. The output of native commands is generated by wrapper stored procedures and then directed to a temporary file by the method. The client may then access the contents of the file with direct SQL queries. This procedure allows the transformed access procedure to perform more efficiently than conventional procedures, while providing same results.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates in general to database management systems performed by computers, and in particular to a remote data access technique utilizing a stored procedure wrapper, wherein system specific data and subroutines may be accessed using SQL. 
     2. Description of Related Art 
     Databases are computerized information storage and retrieval systems. A Relational Database Management System (RDBMS) is a database management system (DBMS) which uses relational techniques for storing and retrieving data. RDBMS software using a Structured Query Language (SQL) interface is well known in the art. The SQL interface has evolved into a standard language for RDBMS software and has been adopted as such by both the American National Standards Organization (ANSI) and the International Standards Organization (ISO). 
     In RDBMS software all data is externally structured into tables. The SQL interface allows users to formulate relational operations on the tables either interactively, in batch files, or embedded in host language, such as C, COBOL, etc. Operators are provided in SQL that allow the user to manipulate the data, wherein each operator operates on either one or two tables and produces a new table as a result. The power of SQL lies on its ability to link information from multiple tables or views together, to perform complex sets of procedures with a single statement. 
     Although SQL is standard to some degree across a number of platforms, including Windows NT, Windows 95, AIX, OS/390 and AS/400, there remains platform specific information that can not be obtained using SQL. Native commands are commands that run only on a specific platform and that cannot be utilized by SQL in conventional approaches. An example of a native command is “DSPFD FILE,” which displays a file description for obtaining file member information on an AS/400 platform. Other examples include “ps -aux” for processing information running on an AIX machine and “SET” for displaying Windows environment information on a Windows NT system. These native commands obtain platform specific information that cannot be directly obtained with SQL. 
     One conventional approach for utilizing system specific routines utilizing SQL is Remote Procedure Call (RPC). RPC is generally a mechanism for allowing subroutines to execute on a remote system across a network. FIG. 1 depicts the difference between a traditional direct procedure call  101  and a remote procedure call  103 . 
     The code that enables RPC to access remote systems is broken into four components, shown in FIG.  2 . The client stub  201  and server stub  203  are compiled C language source files specific to the procedures being sent across the network. The client runtime  205  and server mainline  207  are generic. The user of the RPC describes the interface between the main program  209  and the subroutines  211  using an Interface Definition Language (IDL). The RPC compiler then generates the client stub  201  and the server stub  203  based on the IDL description. Common interface definition languages are Sun&#39;s NIDL and the DCE IDL. 
     Once compiled, the client stub  201  is linked with the client runtime  205  to provide access to the remote procedures that otherwise could not have been accessed with SQL. Similarly, the server stub  203 , once compiled, is linked with the server mainline  207  to format commands prior to calling the actual user&#39;s subroutines. The RPC code must correctly translate data from the format used by the client to the format used by the server and vice versa. This requirement, in turn, yields the constraint that the client stub  201  must be compatible with the server stub  201 . Although RPC is functional in its approach for accessing system specific subroutines, it is limiting in that it requires installation of additional code on both the client and the server systems. 
     A different conventional approach for accessing system specific information is an SQL stored procedure. With this approach, as detailed in FIG. 3, specific procedure programs  301  are stored on a server  303 . The client  305  can then use an SQL statement to invoke the stored procedure on the server side. The process is cumbersome, however. For example, a procedure program  301  must be created and registered using an SQL statement create procedure. The program  301  must then be installed in the server. If, for example, the program  301  is stored on the server  303  at location MYSCH.STRPROC, the client  305  will use the SQL statement: EXEC SQL EXECUTE IMMEDIATE CALL MYSCH.STRPROC to invoke the stored procedure  301  on the server side  303 . The stored procedure  301  then executes native commands to obtain system specific data and the results are passed back. The client SQL call statement  305  must match the signature of the stored procedure  301 . This approach, much like the previously described conventional approach, requires installation of additional code on the server side every time a new client function is required. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a method and system for accessing system specific data without the installation of additional server side code. It is a further object of the invention to provide a method that does not require installation of additional client side code in cases that involve separate requests for the same system specific information. The method of the invention is less complex than conventional methods and results in lower software maintenance costs. 
     One embodiment of the present invention includes a method of using SQL to access system specific information and functions in a computer system. The method utilizes table formatted native command output files as well as “wrapper” stored procedures for running native commands and accessing system specific information through SQL. The method does not require installation of additional code on the server time for each new client function request. 
     Another preferred embodiment of the present invention is a computer system for optimizing an SQL query to system specific information, utilizing the above-described method embodiment of the present invention. 
     Yet another preferred embodiment of the present invention is a program storage device readable by a computer tangibly embodying a program of instructions executable by the computer to perform the above-mentioned method embodiment of the present invention. 
    
    
     The foregoing and other objects, features, and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments, which makes reference to several drawing figures. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring now to the drawings in which like reference numbers represent corresponding parts throughout: 
     FIG. 1 illustrates the traditional procedure call and the Remote Procedure Call (RPC), according to the prior art; 
     FIG. 2 illustrates further details of the RPC, according to the prior art; 
     FIG. 3 illustrates an SQL stored procedure, according to the prior art; 
     FIG. 4 illustrates a computer database hardware and software environment usable in the present invention; and 
     FIG. 5 illustrates a method exemplary of the method of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following description of the preferred embodiments reference is made to the accompanying drawings which form the part thereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural and functional changes may be made without departing from the scope of the present invention. 
     The present invention discloses a method, apparatus and program storage device for optimizing the performance of remote system specific data and functions using SQL statements. The optimized data query technique utilizes a new method that takes advantage of table formatted native command outputs as well as wrapper stored procedures in order to access system specific data using SQL without the need for installation of additional server side code. 
     FIG. 4 illustrates an exemplary computer hardware environment, including a computer system  402 , comprising one or more processors executing instructions stored in its associated computer memory, that could be used with the present invention. The operating memory can be loaded with the instructions received through an optional storage drive or through an interface with the network. In one exemplary environment, the access technique of the present invention is utilized on the same processor site that the system specific data is stored on. However, the technique is especially advantageous when used in a network environment, having at least a database server site with a database processor networked to a client site with a client processor. 
     Each processor is connected to one or more electronic storage devices, such as user and system files  404 , log  406 , and disk drives, that store one or more databases. These drives may comprise, for example, optical disk drives, magnetic tapes and/or semiconductor memory. The storage drive permits receipt of a program storage device, such as a magnetic media diskette, magnetic tape, optical disk, semiconductor memory and other machine-readable storage device, and for program steps recorded on the program storage device to be read and transferred into the computer memory. The recorded program instructions may include the code for the optimized access technique of the present invention. Alternatively, the program steps can be received into the operating memory or over the network. 
     Operators of the computer system  402  use a standard operator terminal interface  408 , such as IMS/DB/DC, CICS, TSO, OS/2 or other similar interface, to transmit electrical signals to and from the computer system  402 , that represent commands for performing various search and retrieval functions, termed queries, against the databases. In the present invention, these queries conform to the Structured Query Language (SQL) standard, and invoke functions performed by Relational DataBase Management System (RDBMS) software. In certain preferred embodiment of the present invention, the RDBMS software comprises the DB2 product offered by IBM. Those skilled in the art will recognize, however, that the present invention has application to any RDBMS software that uses SQL, and may similarly be applied to non-SQL queries. 
     As illustrated in FIG. 4 the DB2 architecture includes three major components: the Resource Lock Manager (IRLM)  410 , the Systems Services module  412 , and the Database Services module  414 . The IRLM  410  handles locking services, because DB2 treats data as a shared resource, thereby allowing any number of users to access the same data simultaneously, and thus concurrency control is required to isolate users and to maintain data integrity. The Systems Services module  412  controls the overall DB2 execution environment, including managing log data sets on the electronic storage device  406 , gathering statistics, handling startup and shutdown, and providing management support. 
     At the center of the DB2 architecture is the Database Services module  414 . The Database Services module  414  contains several submodules, including the Relational Database System (RDS)  416 , the Data Manager  418 , the Buffer Manager  420  and other components  422 , such as an SQL compiler/interpreter. These submodules support the functions of the SQL language, i.e., definition, access control, retrieval, and update of user and system data. The Database Services module  414  preferably comprises one or more processors that execute a series of computer-executable programming instructions to respond to a user query or access call to system specific data or operations. 
     The access technique of the preferred embodiments of the present invention may be utilized on the same processor site where the application table is stored. However, the technique is especially advantageous when used in a network environment. In a network environment the client site calls a “wrapper” stored procedure from the database server site. Output from the execution of the procedure is directed to a temporary file, readable by SQL, which the client can then directly access using SQL. This method, which provides system specific data in an SQL readable format, eliminates the need for additional code to be placed on either the client or the server side for individual queries and access attempts. The present invention ideally works with any heterogeneous sources supported by IBM, such as AS/400, that inherently provide SQL readable native procedure outputs as well as wrapper stored procedures. 
     An embodiment of the present invention may be a method, as illustrated in FIG.  5 . The method, comprising  4  steps, directs the exchange between a client  501  and a server  503  wherein the client  501  uses SQL to access system specific data or functions on a server  503 . In client step  1   505  the client calls a wrapper stored procedure, with the native command passed as the parameter, on the database server  503 . The wrapper stored procedure to run any native commands  515  is an SQL stored procedure registered at a particular location on the database server  503  that may be accessed by SQL. The wrapper stored procedure to run any native commands  515  is then run, in server step  2   507  on the server system  503  as a native procedure in the method schematic. In server step  3   509  the results of the native procedure are directed to a temporary file  517 . The file is formatted such that it is readable by SQL. This enables the utility of client step  4   511  in which the client  501  may directly access the temporary file  517  which contains the system specific information. 
     The present invention, which in a preferred embodiment is implemented on an AS/400 platform, provides several important and significant advantages over the prior art. For example, there is no need to install additional code, including server stubs and stored procedures, on the server/database side. This is possible because the AS/400 system provides wrapper stored procedures as well as SQL readable output formats for native procedures. 
     Other advantages provided by the present invention include reduced complexity in the form of eliminating the need for a conventional client stub in the event that additional clients are required to obtain the same information. Further, the need to keep client/server pairs updated and compatible at all times is eliminated. This directly translates to lower software maintenance costs. Furthermore, upgrade of native commands is independent of the clients. Thus, the native commands can be changed or altered to produce different output fields without affecting the clients, for example, by requiring additional client-side code installation or upgrade. The invention yields a greater degree of separation than that which exists with conventional methods, substantially simplifying software version control between clients and servers. For example, a client does not need to have an exclusive association with a server, and either one may be upgraded or altered without affecting the other. 
     It will be appreciated by those skilled in the art that the present invention may take the form of various embodiments, including methods that work on a variety of platforms. For example, server platforms other than the AS/400 may be considered to be within the scope of the invention should they include wrapper stored procedures and the ability to output the result of native commands into an SQL readable file. Similarly, the invention may utilize any DB2 platform as its client platform. 
     The foregoing description of the preferred embodiment of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.