Executing rules with an embedded rule engine

You can run the rules locally for test purposes using an embedded engine.

When you execute rules in an embedded environment, you deploy and execute a ruleset archive on a single Java™ Virtual Machine (JVM).

The following figure shows an embedded environment and the necessary parts to execute rules by a rule engine:

You must include the rule engine in the class path of the application.

In the application, you use the Rule Designer API to do the following tasks:

• Load a ruleset.

• Instantiate a rule engine.

• Execute the rule engine against objects passed as parameters.

The Java Virtual Machine in which you execute the ruleset must be able to locate the application, the XOM, the rule engine , and the JDK. The following figure shows the necessary components to execute a ruleset.

The rule engine uses a ruleset and a group of objects to evaluate which rules must be fired. Firing a rule means executing the action part of the rule in the context of the objects that have satisfied its conditions.

 Step 1  of this graphic shows that the rule engine is based on pattern matching: it matches rule conditions with a group of objects that are defined by the ruleset parameters.

In  Step 2 , the rule engine creates a rule instance for each match between a rule and an object or group of objects. The execution mode determines the way in which the rule instance is executed.