Developing a hello world application from scratch

The next chapter illustrates the steps to create a hello world application from scratch, compile it, deploy it and eventually debug it.

Writing the source

Programs for the web are standard COBOL programs. The following source code produces a screen with a button with "Hello World" inside:

PROGRAM-ID. HELLO.        SCREEN SECTION.        01  SCREEN1.         03 PUSH-BUTTON             LINE  4             COL   4            SIZE 15            HEIGHT-IN-CELLS            WIDTH-IN-CELLS            TITLE "Hello World"            EXCEPTION-VALUE 100          .        PROCEDURE DIVISION.        MAIN.            DISPLAY STANDARD GRAPHICAL WINDOW.            DISPLAY SCREEN1.            ACCEPT  SCREEN1 ON EXCEPTION CONTINUE.

Compiling the source

Since we plan to debug the program after the deployment, we'll use the -d option.

The -wd2 option is also used to be sure that our program is compatible with Web Direct.

iscc -d -wd2 hello.cbl

Creating the configuration file

In order to run with Web Direct 2.0 we must instruct the program to use a specific guifactory class.

In addition, the license codes for the isCOBOL Framework and Web Direct 2.0 must be provided, so our configuration file will look like this:

iscobol.guifactory.class=com.iscobol.gui.client.zk.GuiFactoryImpl iscobol.license.2017=XXXXXXXXXXXXXXXXXXXXXXX iscobol.eis.license.2017=XXXXXXXXXXXXXXXXXXXXXXX

The configuration file will be placed between program classes in the webapp directories. However, the configuration is also loaded from \etc directory and from the user home directory depending on the drive where Tomcat was started and on the user that owns its process.

Deploying in Tomcat

The easiest way to deploy a new web app is to:

•	Deploy the WD2 sample program as explained in Running the sample application chapter

•	Make a copy of the tomcat/webapps/wd2 folder and rename the copy to the name of your choice (i.e. 'test')

Note - the subfolders "pdf" and "upload" are specific for the WD2 sample; you can either delete them or rename them, depending on your needs. The other subfolders instead should be left unchanged.

•	Add your class files to one of the following:

o	one of the folders listed in iscobol.code_prefix configuration property

or, if iscobol.code_prefix is not set,

o	the WEB-INF/classes folder

o	a jar file placed in the WEB-INF/lib folder

•	Add your properties to the WEB-INF/classes/iscobol.properties file

•	Restart Tomcat

Running the application

From Web browser considering our program that is called HELLO, you will use the following URL: http://127.0.0.1:8080/test/zk/IsMainZK?PROGRAM=HELLO to have:

Debugging

In order to debug the web application

•	Programs must be compiled with -d option

•	The following entry must appear in the configuration

iscobol.rundebug=2

•	The Remote Debugger feature is used

When you connect to the page of your application you will see a blank page. It means that the web application is waiting for the Debugger to connect. Launch the following command to use the Debugger:

iscrun -J-Discobol.debug.code_prefix=sourcePath -d -r serverIp

Where:

•	sourcePath is the list of paths were program source code and copyfiles can be found

•	serverIp is the ip (or name) of the web-server where the web application is running, in our case: 127.0.0.1

If everything has been done correctly, you should see the web page show up while you debug the DISPLAY statements.