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Jadex Rules is a small lightweight rule engine, which currently
employs the well-known Rete algorithm for highly efficient rule
matching. Jadex rules is therefore similar to other rule engines
like JESS and Drools. Despite the similarities there are also
important differences between these systems:
* Jadex Rules is very small and
intended to be used as component
of other software. Even though rules can be specified in a Java
dialect as well as (a small variation of) the CLIPS language
its primary usage is on the API level. Jadex Rules is currently
the core component of the Jadex BDI reasoning engine.
* Jadex Rules cleanly separates between state and rule representation.
This allows the state implementation as well as the matcher to be
flexibly exchanged. Some experiments have e.g. been conducted with
a Jena representation. Regarding the matcher, it is planned to
support also the Treat algorithm, which has a lower memory footprint
than Rete.
* Jadex Rules pays close attention to rule debugging. The state as
well as the rete engine can be observed at runtime. The rule debugger
provides functionalities to execute a rule program stepwise and also
use rule breakpoints to stop the execution at those points.
package jadex.rules.rulesystem;
import jadex.commons.ICommand;
import jadex.commons.ISteppable;
import jadex.commons.concurrent.Executor;
import jadex.commons.concurrent.IExecutable;
import jadex.commons.concurrent.IThreadPool;
import jadex.commons.concurrent.ThreadPoolFactory;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
/**
* A rule system executor can execute rule systems on a separate thread.
*/
public class RuleSystemExecutor implements ISteppable
{
//-------- attributes --------
/** The stepmode flag. */
protected boolean stepmode;
/** Flag indicating that a single step should be performed. */
protected boolean dostep;
/** The agenda. */
protected RuleSystem rulesystem;
/** The executor. */
protected Executor executor;
/** The breakpoints (i.e. rules that set the interpreter to step mode, when activated). */
protected Set breakpoints;
/** The breakpoint commands. */
protected ICommand[] breakpointcommands;
//-------- constructors --------
/**
* Executor for rule systems.
*/
public RuleSystemExecutor(final RuleSystem rulesystem, boolean stepmode)
{
this(rulesystem, stepmode, null);
}
/**
* Executor for rule systems.
*/
public RuleSystemExecutor(final RuleSystem rulesystem, boolean stepmode, IThreadPool threadpool)
{
this.rulesystem = rulesystem;
this.executor = new Executor(threadpool!=null? threadpool: ThreadPoolFactory.createThreadPool(),
new IExecutable()
{
public boolean execute()
{
// Check for breakpoints, if any.
if(breakpoints!=null)
{
Iterator it = rulesystem.getAgenda().getActivations().iterator();
while(it.hasNext())
{
IRule rule = ((Activation)it.next()).getRule();
if(breakpoints.contains(rule.getName()))
{
setStepmode(true);
// Notify listeners
if(breakpointcommands!=null)
{
for(int i=0; i