This is the basic class that implements a behaviour of JADE that allows
  to embed a Jess engine inside the agent code.
  <p>
  <a href="http://herzberg.ca.sandia.gov/jess">Jess</a>
  supports the development of rule-based expert systems.
  <p>
  This JADE implementation has been tested with version 6.0 of JESS.
  <p>
  The programmer can override this class.
  In particular, its methods <code>ACL2JessString</code> and
  <code>JessFact2ACL</code> to convert between ACLMessage JADE structure and
  Jess facts. Also the method <code>ACLJessTemplate</code> might need to
  be overide in order to change the deftemplate of the ACLMessage in Jess.
  <p>
  When this behaviour is added to the list of agent behaviours,
  it creates a Jess engine and initializes the engine by:
  <ul>
  <li> defining the template of an ACLMessage,
  <li> defining the userfuntion "send" to send ACLMessages,
  <li> asserting the fact <code>(MyAgent (name nameofthisagent))</code>,
  <li> parsing the Jess file passed as a parameter to the constructor.
  </ul>
  Then the behaviour loops infinitely by:
  <ul>
  <li> waiting that a message arrives,
  <li> calling the <code>ACL2JessString</code> method that returns the fact to be
  asserted in Jess,
  <li> asserting the fact in Jess,
  <li> running Jess.
  </ul>
  <p>
  Notice for programmers of the Jess .clp file:
  <ul>
  <li> the template of the ACLMessage contains the following slots:
 <pre><code>(deftemplate ACLMessage 
	(slot communicative-act) (slot sender) (multislot receiver) 
	(slot reply-with) (slot in-reply-to) (slot envelope) 
	(slot conversation-id) (slot protocol) (slot language) 
	(slot ontology) (slot content) (slot encoding) 
	(multislot reply-to) (slot reply-by) )
</code></pre>
  <li> match the fact <code>(MyAgent (name nameofthisagent))</code> to know the name of your agent;
  <li> use the userfunction <code>send</code> to send ACLMessages.
  The parameter of <code>send</code> must be a fact-id of type ACLMessage or
  an ACLMessage itself; There are two styles of usage:
  <p> <code>  ?m <- (ACLMessage (communicative-act cfp) (sender ?s))
  <br>
  (send ?m) </code>
  <p> or, in alternative,
  <p> <code>(send (assert (ACLMessage (communicative-act cfp)
  (sender ?s))))</code>
  <li> remember to load all the Jess Packages you need because, by default,
  Jess just loads the built-in functions
  </ul>
  <p>
  Look at the sample file JadeAgent.clp that is shipped with this example.
  <p>
  WARNING:
  FIPA2000 standard has specified an AgentIdentifier to have a
  template
  composed of several slots, where the only mandatory one is the agent name,
  i.e. the globally unique identifier of the agent (GUID).
  In order to reduce the porting of the JESS user code, this basic
  behaviour automatically
  takes care of replacing the GUIDs with full-fledged AgentIdentifiers.