Information management system

Information Management System ( IMS ) is an information system from IBM that can be operated on IBM z Systems servers under z / OS . It consists of the components IMS DB ( hierarchical database system ) and IMS TM ( transaction monitor - former designation: IMS DC). The IMS TM can also be used without the IMS DB. It offers interfaces via APPC , MQSeries , TCP / IP and Java .

IMS is mainly used by banks and insurance companies for applications that require high transaction rates and high system availability.

history

IMS was in 1966 to 1968 (under the name ICS - I nformation C ontrol S ystem) from IBM , North American Rockwell and Caterpillar Tractors for BOM Management of the Apollo moon program developed. The original name for it was BOMP, B ill O f M aterials P rocessor, i.e. parts list processing (was further developed to VBOMP and then abandoned) and the control of the CICS macro level programming was similar. On August 14, 1968, the first version ran at Rockwell Space Division in Downey, California. In 1969, ICS was renamed IMS ( I nformation M anagement S ystem) and constantly further developed by IBM today.

Structure and features

Data is accessed from application programs using DL / I (Data Language Interface, also called Data Language One). This programming interface, a DML , is supported by the Assembler , C , C ++ , COBOL , FORTRAN and PL / I programming languages . IMS contains extensive mechanisms for ensuring data integrity ( locking , logging ).

IMS consists of the components IMS DB ( hierarchical database system ) and IMS TM (formerly known as IMS DC). IMS DB provides here to access databases while IMS TM a transaction monitor is that it allows to process (interactive) under IMS dialogue programs that normally with the user via a 3270 - Terminal communicate / emulation. The IMS DB programming interface is also used here, with communication with the user taking place within the system via a so-called message queue .

Application programs

The following types of application programs exist under IMS :

DL / I

Applications that access IMS databases in pure batch mode . The databases processed by these applications are only available for online operation during program execution if Database Recovery Control (DBRC) and the Internal Resource Locking Manager (IRLM) are activated for this DL / I application. Without DBRC and without IRLM, the following applies: If these databases are to be available online during the day, then such processing can only take place after IMS TM has been terminated.

BMP (Batch Message Processing)

These are programs that are started from a job, but are able to access databases within online operations. These programs are able to access the message queue.

MPP (Message Processing Programs)

These are online applications launched by a user on the 3270 terminal. To do this, the user first fills out a screen mask . After pressing the RELEASE button, a message is generated to the relevant program and inserted in the message queue. IMS TM then starts the program and sends the corresponding message to the program. MPPs are able to process several messages generated by different users. This is why such programs must be programmed in such a way that no session-related data is saved in the program between the dialog steps .

It is possible to use MPP programs via middleware , such as B. Call IMS Connect . Communication takes place via the message queue, so that the application does not notice any difference whether the message was generated by a terminal or a middleware. The advantage of this procedure is the integration of so-called legacy applications into web applications without the application having to be adapted.

Access to IMS databases

There are different approaches to accessing IMS databases from PC applications. For example B. the product IMS Connect , which enables a PC application to send a message to an IMS transaction. The IMS transaction then processes this message without knowing that it was generated by a PC application. The result of this processing is then sent back as a message to the PC application.

Another solution is to use the Shadow Direct product . This solution enables the development of so-called RPCs that are started on the host under the control of Shadow Direct. These RPCs can access IMS databases, among other things. As a result, a relational table can be generated which is sent to the PC application via an ODBC interface.

IMS has supported JDBC since version 7 . This enables direct access to the IMS TM from a Java program. The zAAP Assist processor can be used for this.

The XML-Toolkit for z / OS can be used since version 9 . This supports web applications that require data in XML format. XML data can be stored directly in the IMS DB.

Since version 10, XQuery and XPath can also be used to search stored XML data.

Web links

• Official IBM IMS website

Individual evidence

1. ^ IBM z / VSE Products and Components . IBM . Retrieved June 27, 2009.