Maintain a Custom Function Handler

A Custom Function Handler is a Java or .NET class that implements the com.oracle.determinations.engine.CustomFunctionHandler interface (in Java) or the Oracle.Determinations.Engine.CustomFunctionHandler interface (in .NET). A single method evaluate (or Evaluate in .NET) is implemented to evaluate the function and return the result.

The CustomFunctionDeclaration parameter supplies a definition for the custom function, the most useful property of which is the name of the custom function (in case more than one custom function is required). Parameters to the function are supplied as an object array, although these objects will all be string objects in practice.

In a rulebase, a custom function handler is called by using the CallCustomFunction function:

The first parameter is the name of the function which will come through the CustomFunctionDeclaration. The second parameter is a comma-separated list of identifiers, which will be passed to the custom function handler via the object array. Installation of a custom function handler can be accomplished in one of two ways:

The custom function handler can be installed manually in an application that uses the engine directly (by calling Session.setCustomFunctionHandler).
The handler can be packaged in the compiled rulebase zip file. To do this the compiled .NET assembly DLL or Java JAR file must be copied into the include folder of the rulebase project along with a rulebase configuration file that specifies which class implements the custom function handler.

Maintain a Custom Function Handler

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