Guidelines for writing a web application

Web Direct 2.0 allows bringing GUI COBOL programs into the web without specific modification.

Each COBOL program with a Screen Section containing graphical controls can run as web application with Web Direct 2.0.

However, not all GUI features are supported by Web Direct. If you plan to bring an existing COBOL application into the web It is strongly suggested to compile all sources with the -wd2 option. In this case the isCOBOL Compiler will alert you with warning messages if an unsupported feature is being used. For example, the following Frame definition

03 fr frame               line 2, col 2               lines 10 size 30               height-in-cells               width-in-cells               fill-color 2, fill-percent 50

Will produce the following warnings at compile time:

--W: #179 WD2: Unsupported FILL-COLOR in FRAME control; --W: #179 WD2: Unsupported FILL-PERCENT in FRAME control;

More details about the unsupported features are provided in Known limitations and differences between Swing and Web Direct 2.0.

In order to produce a fast web application, It is strongly suggested to:

•	Reduce the number of controls in the screen

•	Avoid using embedded and event procedures if not necessary

It's very important to avoid using STOP RUN statement if you plan to run your programs as web application. STOP RUN causes the whole JVM to exit and it would result in the shutdown of the whole servlet container. Use GOBACK instead.