10. Instrumentation Functions

10 Instrumentation Functions

A user-defined instrumentation function for each object attaches the managed objects to real resources. This function is called by the agent on a get or set operation. The function could read some hardware register, perform a calculation, or whatever is necessary to implement the semantics associated with the conceptual variable. These functions must be written both for scalar variables and for tables. They are specified in the association file, which is a text file. In this file, the OBJECT IDENTIFIER, or symbolic name for each managed object, is associated with an Erlang tuple {Module,Function, ListOfExtraArguments}.

When a managed object is referenced in an SNMP operation, the associated {Module, Function, ListOfExtraArguments} is called. Th