When a user runs an application, an Open event is triggered in the Application object. The script you write for the Open event initiates the activity in the application. Typically it sets up the environment and opens the initial window. For a server component, there may be no application-level scripts.
When a user ends an application, a Close event is triggered in the Application object. The script you write for the Close event usually does all the cleanup required, such as closing a database or writing a preferences file.
If there are serious errors during execution, a SystemError event is triggered in the Application object.
Batch applications
If your application performs only batch processing, all processing
takes place in the script for the application Open event.
Table 5-1 lists all events that can occur in the Application object. The only event that requires a script is Open.
Event |
Occurs when |
|---|---|
Open |
The user starts the application. |
Close |
The user closes the application. Typically, you write a script for this event that shuts everything down (such as closing the database connection). |
SystemError |
A serious error occurs at runtime (such as trying to open a nonexistent window). If there is no script for this event, PowerBuilder displays a message box with the PowerBuilder error number and message text. If there is a script, PowerBuilder executes the script. For more about error handling, see “Handling errors at runtime”. |
Idle |
The Idle PowerScript function has been called and the specified number of seconds has elapsed with no mouse or keyboard activity. |
