Designing and Managing Behavior Models - Using Trap Masks - Writing a Trigger Function -
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Writing a Trigger Function

If a mask cannot completely describe the type of trap it is looking for by specifying the contents of the trap's Generic trap, Enterprise, and Specific trap fields, it must contain a trigger function. This function, which you write using Perl, can include additional conditions that the trap must meet, and it can fire different triggers as appropriate.

Most trigger functions are very similar in structure. They follow this pattern:

The conditions, which can be arbitrarily complex, generally test the contents of a trap's variable bindings. However, they can test other information as well; for example, a condition can determine whether a trap came from a particular node. The FireTrigger() function fires a trigger, whose name, subobject, and node you can control.

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Note    The maximum length for trigger names is 255 characters.

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To assist you in writing trigger functions, NerveCenter provides:

• A set of functions that enable you to examine the contents of a trap's variable bindings and to fire triggers, among other things
• A set of predefined variables that give you access to information about the trap you're examining, such as the community string in the trap's SNMP message
• A pop-up help menu in the trigger function editing area that lists all the NerveCenter functions and variables available for use in a trigger function.

For further information about these predefined functions and variables and the pop-up help menu, see the following sections:

• Functions for Use in Trigger Functions
• Variables for Use in Trigger Functions
• Using the Pop-Up Menu for Perl

Also, see the section Examples of Trigger Functions. This section presents several sample trigger functions that show a number of the functions and variables being used in context.