The application programmer conducts a "unit test" to test the functionality of a particular module being developed. The programmer uses job monitoring and viewing software such as SDSF to track the running compile jobs, view the compiler output, and verify the results of the unit tests. If necessary, the programmer makes the appropriate corrections to source code or other objects.

Sometimes, a program will create a "dump" of memory when a failure occurs. When this happens, a z/OS® application programmer might use tools such as IBM® Debug Tool and IBM Fault Analyzer to interrogate the dump output and to trace through executing code to find the failure or misbehaving code.

Some mainframe application programmers have now switched to the use of Interactive Development Environment (IDE) tools to accelerate the edit/compile/test process. IDE tools such as the WebSphere® Studio Enterprise Developer are used to edit source code on a workstation instead of directly on the host system, to run compiles "off-platform," and to perform remote debugging.

The use of the IDE is particularly useful if hybrid applications are being built that employ host-based programs in COBOL or transaction systems such as CICS® and IMS™, but also contain a Web browser-like user interface. The IDE provides a unified development environment to build both the online transaction processing (OLTP) components in a high-level language and the HTML front-end user interface components. Once the components are developed and tested, they are packaged into the appropriate deployment format and passed to the team that coordinates production code deployments.

Besides new application code, the application programmer is responsible for the maintenance and enhancement of existing mainframe applications. In fact, this is the primary job for many high-level language programmers on the mainframe today. And, while most z/OS customers are still creating new programs with COBOL or PL/I, languages such as Java™ have become popular for building new applications on the mainframe, just as on distributed platforms.

However, for those of us interested in the traditional languages, there is still widespread development of programs on the mainframe in high-level languages such as COBOL and PL/I. There are many thousands of programs in production on mainframe systems around the world, and these programs are critical to the day-to-day business of the corporations that use them. COBOL and other high-level language programmers are needed to maintain existing code and make updates and modifications to those programs.

Also, many corporations continue to build new application logic in COBOL and other traditional languages, and IBM continues to enhance the high-level language compilers to include new functions and features that allow these languages to continue to exploit newer technologies and data formats.