Each technology adapter is an IF-Prolog module with a common external interface used by the Gate framework. The module concept for the technology adapters is similar to the concept of class used in object oriented programming. A specialized or extended technology adapter module inherits methods from the derived base technology adapter, much in the way of virtual methods in C++.
The Basic technology adapter is what can be considered as the root of this hierarchy of modules. It exports "callback predicates" for cyclic polling, poll responses and traps to be called by the "callback" module of Gate. The callback predicates in turn call control, optional and mandatory methods. Methods are predicates used like virtual C++ methods that are inherited to extended agent handlers.
The Fore technology adapter presented in this paper extends the MIB-II module, which in turn extends the Basic SNMP module. In the sample code presented below, the Prolog fact extends('MIB-II') is used to indicate this inheritance relationship.
% NAME: 'Fore' - GateNM Customized Agent Handler 'Fore'
% DESCRIPTION:
% Frame generated by createAgentHandlerTemplate('Fore', 'MIB-II').
:- module 'Fore'.
:- begin_module 'Fore'.
:- import(framework).
:- import('Basic').
extends('MIB-II').