In 4.1 What Is a Process and What Is a Function? the concept of a process and the functions within it were briefly described. Also mentioned was the fact that the functions within a process consist of a series of RDML commands. These commands are the "program" that defines to the IBM i exactly what is to be done by the function.
You may also remember that the RDML commands could come from 2 sources. They could be automatically generated by an Application Template or could be manually input by the user.
These commands cannot be executed by the IBM i until they are "compiled". This means that they are converted into a form that can be executed by the IBM i.
Most programming languages that run on the IBM i require that programs be compiled. If you have written RPG, COBOL or PL/I programs you will be familiar with the concept of compiling a program.
LANSA is no different. The RDML commands that make up each function in a process must be compiled into an IBM i executable form.
However, within LANSA the process is a little different. The following steps are performed:
1. The RDML commands associated with each function in the process are read and checked for errors.
2. If RDML commands are used that display information on a workstation, an IBM i "display file" will be designed and created. A "display file" is a special type of IBM i file that is used to read from and write to a workstation.
3. The RDML commands are then converted into an RPG program which is compiled just like any other RPG program.
Note: Any process (or more correctly, function within a process) must be "compiled" before it can be used. A function must be compiled when it is first created and must be re-compiled after it has been changed.