Handling Exceptions

This chapter explains how ILE RPG exception handling works, and how to use:

• Exception handlers
• ILE RPG-specific handlers
• ILE condition handlers
• Cancel handlers

ILE RPG supports the following types of exception handlers:

• RPG-specific handlers, for example, the use of an error indicator, an 'E' operation code extender, a MONITOR group, or a *PSSR or INFSR error subroutine.
• ILE condition handlers, user-written exception handlers that you register at run time using the ILE condition handler bindable API CEEHDLR.
• ILE cancel handler which can be used when a procedure ends abnormally.

Most programs benefit from some sort of planned exception handling because it can minimize the number of unnecessary abnormal ends (namely, those associated with function checks). ILE condition handlers also allow you to handle exceptions in mixed-language applications in a consistent manner.

You can use the RPG exception handlers to handle most situations that might arise in a RPG application. The minimum level of exception handling which RPG provides is the use of error indicators on certain operations. To learn how to use them, read the following sections in this chapter:

• ILE RPG Exception Handling
• Specifying Error Indicators or the 'E' Operation Code Extender
• Using a File Error (INFSR) Subroutine
• Using a MONITOR Group
• Using a Program Error Subroutine

Additionally, to learn how ILE exception handling works, read:

• Exception Handling Overview (for general concepts)
• Using RPG-Specific Handlers
• The sections on error handling in ILE Concepts.

For information on exception handling and the RPG cycle, see IBM Rational Development Studio for i: ILE RPG Reference.