Having looked at the key elements of a business application, and how CICS addresses these elements, it’s time to consider the process for developing the components of a business application. The stages of the process are:
Design
Programming
Test and debug
Deployment
It’s important to ensure that there is agreement on what each component is required to do. Make sure you document the design of your component thoroughly, and share it with people who are designing other components. Document your component’s interface, if it has one that other components use. Include assumptions about performance and capacity.
If your component has a user interface, test it out on paper first by drawing all of the proposed screens, and asking some of the intended users to check your design by attempting to “use” the screens. Put yourself in the position of the computer, in order to check what happens when it makes a functional request.
Finding problems at the design stage is essential; it is much cheaper and quicker to fix them earlier rather than later.
For each component in our sample application, you will find that there is a chapter describing the design. In these chapters we consider the factors influencing the design of the component, which lead to the decisions made by the component designer.
Read the design document! The main job of the programmer is to implement the design, as documented. At the same time, the programmer should follow:
Good practice for the language in which the component will be written.
Good practice for the environment in which the component will be running.
Local conventions with regard to file naming, and so on.
For each component in our sample application, we show how to convert the design into a working program.
Testing is an integral part of any software development, and must be as carefully prepared and implemented as the development of the product itself. There are many different methods for testing and several standards have been developed. It is outside the scope of this book to describe testing standards in detail; however, here are a few useful guidelines:
Test each component in isolation.
Test the application as a whole, that is, from end-to-end. This book covers:
Visual Basic to COBOL
MQSeries to COBOL
Web to Java to COBOL
IBM 3270 green screen using CICS BMS (Basic Mapping Support) to COBOL
Load/Stress the application:
Concurrent users
Running in a system with a high workload
Your testing will inevitably uncover errors in the component’s logic or programming. These then need to be removed, a process known as debugging. Chapter 16, describes some of the debug tools available in CICS, and shows some sample debug screens.
Once each component has been designed, programmed, tested, and debugged, it must be deployed correctly. At the same time, the configuration files for the various runtime products must be updated to recognize the components.
Appendix A describes the deployment of our sample application.