Event Points

APPX event points provide opportunities to insert procedural code, or statements, from the Integrated Language Facility (ILF) into the execution sequence of a process. They are entered through a specialized editor that validates syntax at entry time. Refer to Chapters 4-1 thru 4-7 of this manual for definitive information on APPX’s integrated procedural language.

Event points permit you to respond effectively to unusual or unique application requirements that are not addressed by APPX specifications. Each event point can contain a sequence of statements that execute at a specific, predetermined point within an APPX process. Commonly used groups of statements can be defined once in a subroutine process, and then accessed in an event point or executed as an automatic or optional child.

As indicated in Chapter 3-1, event points operate at four levels: process, frame, image, and child invocation. In addition, each type of process varies slightly in the specific event points it includes at each level. Table 3-1-3 summarizes the event points that execute for each process type.

The following sections define each event point, including the chronology according to which it executes, in general terms. You should note, however, that event point execution can be affected by a number of factors, including the process type, the mode and interactive phase, the existence of ancestor and descendent processes, and potential interdependencies between statements in other event points.

Because of the variety of ways you can use event points, it is important to step through the execution sequence of your process using the ILF debugger, verifying the placement of ILF routines. Indications that you may have used the wrong event point to perform a desired action include actions that are never performed, conditional actions that are performed in every instance, and an action performed at any time other than that intended.