System message objects for communicating between an application and a database management system

[0002] This application is related to the following co-pending and commonly-assigned patent applications:

[0003] U.S. patent application Ser. No. 09/435,150, entitled “COMMUNICATION AND INTERACTION OBJECTS FOR CONNECTING AN APPLICATION TO A DATABASE MANAGEMENT SYSTEM”, filed on same date herewith, by Kyle J. Charlet, Haley Fung, Judith E. Hill, Gerald D. Hughes, Steve T. Kuo, Doris Wai-Yee Ling, H. Moncrief Rowe-Anderson, and Jack C. Yuan, attorneys' docket number ST9-99-068;

[0004] U.S. patent application Ser. No. 09/342,010, entitled “APPLICATION PROGRAMMING INTERFACE FOR CREATING AUTHORIZED CONNECTIONS TO A DATABASE MANAGEMENT SYSTEM', filed by Gerald L. Carpenter, Richard D. Housh, Steve T. Kuo, Bruce E. Naylor, Richard L. Stone, and Jack C. Yuan, on Jun. 28, 1999, attorneys' docket number ST9-99-014, now U.S. Pat. No. 6,381,606, issued Apr. 30, 2002;

[0005] which applications are incorporated by reference here.

[0006] 1. Field of the Invention

[0007] The present invention relates generally to computerized methods for accessing databases, and in particular, to system message objects for communicating between an application and a database management system.

[0008] 2. Description of Related Art

[0009] It is well known in the art to use database management systems, such as IBM's IMS (Information Management System) database management system DBMS), to manage computerized databases. Indeed, IMS has been used for decades and remains in use today. Currently, there is a need to access such “legacy” databases using. application programs. However, such tasks are complex and there are few tools available to assist application program developers.

[0010] IMS Open Transaction Manager Access (OTMA) is a high performance client/server protocol that allows application programs to access an IMS DBMS. However, the application program must include an interface to the IMS OTMA, which can be difficult to develop. To interface with an IMS DBMS requires rather extensive knowledge of the architecture of the IMS DBMS, as well as the architecture of the MVS operating system. Moreover, because of security considerations with regard to accessing an IMS DBMS, a great deal of skill is involved in establishing a connection between an application program and the IMS DBMS, since it must interface with the operating system as a secure and trusted “user”.

[0011] In order to more fully provide access to an IMS DBMS, it would be advantageous to have an easier mechanism to connect to the IMS DBMS and run transactions thereby. Thus, there is a need in the art for improved techniques for accessing a hierarchical database management system.

[0012] To overcome the limitations in the prior art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention discloses a method, apparatus, and article of manufacture for accessing a database management system. A database management system (DBMS), executed by a server computer, manages one or more datastores stored on the computer. The DBMS includes an Open Transaction Manager Access (OTMA) that provides a high level application programming interface (API) for an application program to access the DBMS and its datastores, wherein the OTMA allows the application program to create an authorized connection with the DBMS. The server computer also executes a TCP/IP OTMA Connection (TOC) that accepts and manages connections between the DBMS and the application program. In the preferred embodiment, the application comprises a JAVA servlet or applet executed by a JAVA Virtual Machine UVM). A TOC Connector for JAVA interfaces the JVM to the TOC, wherein the TOC Connector for JAVA includes one or more objects for establishing a connection between the servlet or applet executed by the JVM and the OTMA of the DBMS, so that transactions can be transmitted from the application program to the DBMS over the established connection and results of the transmitted transactions can be received at the application from the DBMS.

[0013] Various advantages and features-of novelty, which characterize the invention, are pointed out with particularity in the claims annexed hereto and form a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to accompanying descriptive matter, in which there is illustrated and described specific examples of an apparatus in accordance with the invention.

[0014] Referring now to the drawings in which like reference numbers represent corresponding parts throughout:

[0015] FIG. 1 is a block diagram illustrating an exemplary hardware and software environment used to implement the preferred embodiment of the present invention;

[0016] FIG. 2 is a block diagram illustrating an exemplary logical structure of the preferred embodiment of the present invention; and

[0017] FIG. 3 is a flowchart illustrating the logic performed according to the preferred embodiment of the present invention.

[0018] In the following description of the preferred embodiment, reference is made to the accompanying drawings, which form a part hereof, and in which is shown byway of illustration a specific embodiment in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.

[0019] The IMS Open Transaction Manager Access (OTMA) provides a high level application programming interface (API) for application programs to access an IMS database management system (DBMS) and its datastores. The IMS OTMA also provides easy access to an IMS datastore by creating an “authorized” path to or connection with the IMS database. As a result, application programs accessing the data in the IMS DBMS can be more readily written by programmers having less familiarity with the internals of the IMS DBMS and operating system.

[0020] With this simple and easy to use interface, an application program can submit a transaction or command to the IMS DBMS and receive the results therefrom without the necessity of understanding protocols of the IMS OTMA. Thus, the present invention offers improved IMS application programming productivity

[0021] FIG. 1 is a block diagram illustrating an exemplary hardware and software environment used to implement the preferred embodiment of the invention. The environment includes one or more server computers 100 and, optionally, one or more client computers 102. Both the server computers 100 and client computers 102 typically are comprised of one or more processors, random access memory (RAM), read-only memory (ROM), and other components such as data storage devices and data communications devices.

[0022] The server computer 100 executes a database management system (DBMS) 104, which in the preferred embodiment comprises the Information Management System (IMS) DBMS sold by IBM Corporation, the assignee of the present invention. The IMS DBMS 104 manages one or more datastores 106 stored on one or more data storage devices 108. The datastore 106 comprises a hierarchic collection of data, wherein information is organized in a pyramid fashion with data at each level of the hierarchy related to, and in some way dependent upon, data at the higher level of the hierarchy.

[0023] According to the preferred embodiment of the present invention, applets are executed by a JAVA Virtual Machine (JVM) 110 executed by the client computer 102 and/or servlets are executed by a JVM 112 executed by the server computer 100. The JVM 110, 112 interfaces to the IMS DBMS 104 via an IMS TCP/IP OTMA Connection (TOC) 114, which connects to a Cross-Coupling Facility (XCF) 116, that in turn interfaces to an IMS Online Transaction Manager Access (OTMA) 118, which comprises an application programming interface (API) to the IMS DBMS 104. These various components perform these various steps in order to establish a connection between the JVM 110, 112 and the IMS DBMS 104, send transactions from the JVM 110, 112 to the IMS DBMS 104 over the established connection, and receive results of the transactions from the IMS DBMS 104 at the JVM 110, 112 over the established connection.

[0024] Generally, these components 104, 106, 110, 112, 114, 116, and 118 all comprise logic and/or data that is embodied in or accessible from a device, medium, or carrier, e.g., a data storage device, a data communications device, a remote computer or device coupled to the computer via a data communications device, etc. Moreover, this logic and/or data, when read, executed, and/or interpreted by a computer, causes the computer to perform the steps necessary to implement and/or use the present invention.

[0025] Thus, the present invention may be implemented as a method, apparatus, or article of manufacture using standard programming and/or engineering techniques to produce software, firmware, hardware, or any combination thereof. The term “article of manufacture” (or alternatively, “computer program product”) as used herein is intended to encompass logic and/or data accessible from any computer-readable device, carrier, or media.

[0026] Those skilled in the art will recognize that any combination of the above components, or any number of different components, including different logic, data, different computers, devices, or peripherals, may be used to implement the present invention, so long as similar functions are performed thereby. Specifically, those skilled in the art will recognize that the present invention may be applied to any database and associated database management system.

[0027] FIG. 2 is a block diagram that illustrates the components and structure of the components executed by the JVM 110, 112 according to the preferred embodiment of the present invention. The JVM 110, 112 executes one or more Java applications 200 (either applets or servlets), which interface to an IMS TOC Connector for Java 202 executed by the JVM 110, 112. In essence, the IMS TOC Connector for JAVA 202 allows the application program 200 to act as a TCP/IP client to the IMS TOC 114 executed by the server computer 100.

[0028] The IMS TOC Connector for JAVA 202 includes the following classes (which are instantiated as JAVA Beans):

[0029] An IMS Communication bean 204 representing the communications session established between the application program 200 and the IMS TOC 114, as well as the target IMS DBMS 104 and IMS datastore 106.

[0030] An IMS Connection Spec bean 206 representing the connection between the application program 200 and the IMS TOC 114, as well as the target IMS DBMS 104 and IMS datastore 106.

[0031] An IMS Interaction Spec bean 208 representing the type of interaction that the application program 200 has with the IMS TOC 114, as well as the target IMS DBMS 104 and IMS datastore 106.

[0032] An IMS Logon Info bean 210 representing Logon information for the duration of a session.

[0033] A DFSMO1A bean 212 and a DFSMO1B bean 214 to process potential error messages returned from the IMS DBMS 104. These messages begin with the three characters ¢DFS.”

[0034] The application program 200 is developed using a programming development tool (such as IBM's VISUAL AGE FOR JAVA). In addition to interfacing with the above beans, the application is usually a composite “bean” that includes the following:

[0035] A Record Selector bean 216 that discriminates between normal input/output messages and error messages.

[0036] An Input Message bean 218 representing the input to the IMS transaction.

[0037] An Output Message bean 220 representing the output from the IMS transaction;

[0038] Generally, these components 200, 202, 204, 206, 208, 210, 212, 214, 216, 218, and 220 all comprise logic and/or data that is embodied in or accessible from a device, medium, or carrier, e.g., a data storage device, a data communications device, a remote computer or device coupled to the computer via a data communications device, etc. Moreover, this logic and/or data, when read, executed, and/or interpreted by a computer, causes the computer to perform the steps necessary to implement and/or use the present invention.

[0039] Thus, the present invention may be implemented as a method, apparatus, or article of manufacture using standard programming and/or engineering techniques to produce software, firmware, hardware, or any combination thereof. The term “article of manufacture” (or alternatively, “computer program product”) as used herein is intended to encompass logic and/or data accessible from any computer-readable device, carrier, or media.

[0040] Those skilled in the art will recognize that any combination of the above components, or any number of different components, including different logic, data, different computers, devices, or peripherals, may be used to implement the present invention, so long as similar functions are performed thereby. Specifically, those skilled in the art will recognize that the present invention may be applied to any database and associated database management system.

[0041] FIG. 3 is a flowchart that illustrates the logic performed according to the preferred embodiment of the present invention. Essentially, this logic provides a high-level overview of how to build and operate a JAVA application program 200 that accesses an IMS transaction.

[0042] Block 300 represents the creation of an IMS Connection Spec bean 206 to be used for the connection to IMS TOC 114. The IMS Connection Spec bean 206 provides information about the TCP/IP connection between the application program 200 and the IMS TOC 114, as well as information about connection management.

[0043] The following information is provided to the IMS Connection Spec object 206:

[0044] TCP/IP hostname of the server computer 100 running IMS TOC 114 that will be used by the application program 200, and

[0045] Port number associated with IMS TOC 114 that will be used by the application program 200.

[0046] Block 302 represents the creation of an IMS Interaction Spec bean 208 to be used for the interaction between the JAVA application program 200 and the IMS DBMS 104. The IMS Interaction Spec bean 208 provides information about the interaction between the application program 200 and the IMS DBMS 104.

[0047] The following information is provided to the IMS Interaction Spec bean 208:

[0048] Datastore Name—The name of the target IMS datastore 106.

[0049] LTerm Name—The LTERM (Logical Terminal) name used to override the LTERM name associated with the application program 200 in the IMS DBMS 104.

[0050] Map Name—The map name is provided by the application program 200 to identify the output of a transaction.

[0051] Mode—The Mode identifies the type of interaction to be carried out between the application program 200 and the IMS DBMS 104. The default mode is MODE_SEND_RECEIVE.

[0052] Sync Level—The Sync Level specifies the transaction synchronization level that the application program 200 is to have with IMS OTMA 118.

[0053] Block 304 represents the creation of Input/Output Message beans 218, 220 to represent the input and the output to the IMS transaction. In a preferred embodiment, COBOL source files that contain definitions of the IMS transaction input and output messages are parsed in order to generate these corresponding beans 218, 220.

[0054] Message segments that are sent to and received from IMS transactions always begin with a 2-byte length field (called LL), followed by a 2-byte field that contains IMS information (called ZZ). The 2-byte length field represents the length of the entire message segment, including the LL and ZZ fields. The data of the message segment follows the LL and ZZ fields. In the case of the first segment of the transaction's input message, the data portion of the segment also contains the transaction code. The application program 200 must set the fields of a transaction input message segment before sending that segment to the IMS DBMS 104.

[0055] Block 306 represents the creation of DFS beans 214, 216 to represent IMS DFS messages, i.e., the DFSMO1A and DFSMO1B beans 214, 216. The DFSMO1A and DFSMO1B beans 214, 216 together represent IMS error messages that may be returned by the IMS DBMS 104 in response to a command or a transaction. These messages typically begin with the characters DFS, and might or might not indicate an error situation. Because the characters DFS are sometimes preceded by a control character, two output beans (DFSMO1A bean 212 and DFSMO1B bean 214) are used to handle these IMS DFS messages. Both DFS beans 214, 216 provide a getDFSMessage( ) method to access the message, starting with the DFS prefix.

[0056] Block 308 represents the creation of a Record Selector bean 212 that is used by the application program 200 to choose between the output of the IMS transaction or IMS command, and the two forms of IMS DFS messages. The Record Selector bean 212 populates the appropriate bean 214, 216, or 220 based on the message that is returned from the IMS DBMS 104.

[0057] Block 310 represents the creation of an IMS Communication bean 204 and Block 312 represents the connection of the application program 200 to the IMS TOC 114 by invoking a connect method of the IMS Communication bean 204.

[0058] Blocks 314, 316 represent the application program 200 displaying a user interface and accepting input from the user interface, so that a user ID, password, and group name can be provided for the IMS transaction. For example, if the JVM 110 is executed by a Web browser, and the application program 200 is an applet performed by the Web browser, then the input to the IMS transaction is provided by a Web browser in an input HTML page that is then provided to the applet. In an alternative example, if the JVM 112 is executed by a Web server, and the application program 200 is a servlet performed by the Web server, then the input to the IMS transaction is provided by a Web browser in an input HTML page that is transmitted to the Web server and provided to the servlet.

[0059] Blocks 318, 320 represent the application program 200 displaying a user interface and accepting input from the user interface, so that other input data can be provided for the IMS transaction.

[0060] Block 322 represents an IMS transaction being invoked by the application program 200. Generally, the transaction is invoked by an execute method of the application program 200 that uses the IMS TOC Connector 202 to submit a message to the IMS OTMA 118.

[0061] Blocks 324, 326 represent the application program 200 displaying a user interface and then displaying the output to the user interface, so that results data from the IMS transaction can be provided to the user. Usually, the results is translated into an HTML page that is displayed by a Web browser.

[0062] This concludes the description of the preferred embodiment of the invention. The following describes some alternative methods of accomplishing the same objects.

[0063] In alternative embodiments of the present invention, other types and configurations of computers could be used. For example, mainframes, minicomputers, or personal computers, could be used with the present invention.

[0064] In alternative embodiments of the present invention, other types and configurations of computer programs could be used. For example, the invention need not be restricted to client-server configurations.

[0065] In alternative embodiments of the present invention, other database management systems could be used. For example, the invention need not be restricted to IMS™ database management systems and databases.

[0066] In summary, the present invention discloses a method, apparatus, and article of manufacture for accessing a database management system. A database management system (DBMS), executed by a server computer, manages one or more datastores stored on the computer. The DBMS includes an Open Transaction Manager Access (OTMA) that provides a high level application programming interface (API) for an application program to access the DBMS and its datastores, wherein the OTMA allows the application program to create an authorized connection with the DBMS. The server computer also executes a TCP/IP OTMA Connection (TOC) that establishes and manages connections between the DBMS and the application program. In the preferred embodiment, the application comprises a JAVA servlet or applet executed by a JAVA Virtual Machine (JVM). A TOC Connector for JAVA interfaces the JVM to the TOC, wherein the TOC Connector for JAVA includes one or more objects for establishing a connection between an applet or servlet executed by the JVM and the OTMA of the DBMS, so that transactions can be transmitted from the application program to the DBMS over the established connection and results of the transmitted transactions can be received at the application from the DBMS.

[0067] 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.