4.1 What Is a Process and What Is a Function?
A process is a group of related functions.
When used in an interactive environment a process appears to be a menu of associated functions.
When used in a batch environment a process usually consists of only one function or a group of closely related functions (such as related reports).
A function is an executable IBM i "program" that was defined by a user and created by LANSA.
A function usually manipulates the IBM i database in some way.
For instance an interactive process named ORDERS which has 4 functions associated with it can be visualized like this:
_____________________________________________
| |
| PROCESS : ORDERS |
| |
| Enter number or place cursor on same line : |
| |
| _ 1. Input details of a new order |
| 2. Change an existing order |
| 3. Browse customer master file |
| 4. Browse product master file |
| |
|______________________________________________|
|
_____________________|______________________
| | | |
_____|_____ ______|_____ ______|_____ _____|______
| | | | | | | |
|Function 1 | | Function 2 | | Function 3 | | Function 4 |
| | | | | | | |
|Input new | | Change | | Browse | | Browse |
| order | | existing | | Customer | | Product |
| | | order | | Master | | Master |
|___________| |____________| |____________| |____________|
Some of the characteristics of processes and functions are:
- A function must "belong to" or be "owned by" a process
- Both processes and functions must have names. A process name must be unique within the entire LANSA partition. A function name must be unique within the process to which it belongs.
- Functions can be created automatically using an "Application Template". An application template asks the user a series of questions and then generates the function automatically.
- Functions can also be created manually. In this case the user must manually specify the commands that are to executed within the function.
- All functions contain a series of commands that define the "program" that is to be created. If the function was created automatically then the commands were created automatically, if the function was created manually then the commands must be entered manually.
- The ability to manually define and change the commands associated with a function is what gives LANSA its power, flexibility and speed in creating IBM i application programs.
- The commands within a function are called RDML commands where RDML is an acronym for "Rapid Development & Maintenance Language". RDML commands work at very high level. One LANSA RDML command may perform the same work as 100 or more commands in programming languages such as RPG, COBOL or PL/1.
The topics in this chapter describe how processes and functions are created and changed using the LANSA system.