/*
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				  RETSINA(tm)
    Reusable Environment for Task Structured Intelligent Network Agents(tm)

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*/
/* Copyright (c) 1998, Dirk Kalp, Katia Sycara, RETSINA Project,
                       Carnegie Mellon University
   All rights reserved
*/

/*----------------------------------------------------------------------------
  HISTORY:
    Spring/Summer 1998 Dirk Kalp (kalp@cs.cmu.edu)
    Created the module.

    Dec 03 1998 Dirk Kalp (kalp@cs.cmu.edu)
    Added this HISTORY log. 
----------------------------------------------------------------------------*/
package EDU.cmu.softagents.retsina.Communicator;



/** Keeping a log of the msgs an agent sends to or receives from
    other agents is a service the Communicator can provide. To do
    this, the Communicator expects that a logging facility exists
    outside the Communicator to handle the actual details of msg
    logging. The Communicator defines a standard interface, the
    MsgLogInterface given here, by which it will provide to a
    logging facility the msgs to be logged. The logging facility
    must implement this interface. When the Communicator is
    instantiated, a reference to the logging facility is passed to
    it. In fact, the Commuincator receives a list of logging
    facilities since there may be a desire to support different
    kinds of logging (eg., to a file, to a graphical display, to a
    logging agent, etc.).

    MsgLogInterface provides a set of methods for establishing
    and invoking standard facilities for logging agent to agent
    msg traffic into and/or out of an agent. A logging facility
    will implement this interface. If the logging facility has an
    associated external logging agent to which the log msgs are sent,
    then the constructor of the logging facility that implements this
    MsgLogInterface should provide for access to the Communicator so
    that the logs can be transmitted to the logging agent. Furthermore,
    if the logging facility wishes to provide control of logging (eg.,
    ^Q, ^S) to the logging agent, then the constructor of the logging
    facility should also create a thread to receive and handle these
    control msgs from the logging agent. One way to receive such
    control msgs is to establish a queue for them to be routed to
    using the Communicator's routeInputMsgs() method. This establishes
    a special reply-with ID that the logging agent uses in its control
    msgs. The Communicator will recognize this reply-with ID and use
    it to route the msgs to the queue from which thsy are processed
    by the log facility's thread.
*/    

public interface MsgLogInterface {

  /** This method will be called by the Communicator at startup to
      initialize the logging facility. The Communicator passes a
      reference to itself to provide the means for the logging
      facility to communicate with an associated logging agent, if
      one exists. The logging agent would receive all the msgs to
      be logged and could also send cmds to the logging facility to
      control the logging. The name of the agent whose msgs are being
      logged is also passed in as an arg by the Communicator. Returns
      true if the logging facility was successfully initialized, false
      otherwise.
  */
  public boolean logInit(String agentName, String agentInfo, Communicator comm);


  /** This method is used to record a msg that the agent has sent
      to another agent. The method may write the msg to a file, send
      it to some msg logging agent, etc. It may also perform no logging
      directly if the instantiated logging facility creates its own
      thread and has an associated external logging agent to which it
      sends msgs for logging. With this arrangement, the logging agent
      can send cmds to the logging facility's thread to control logging
      activity with its own agreed upon set of cmds such as suspend/resume
      logging of msgs. Return true on success, false otherwise.
  */
  public boolean logMsgSentByAgent(InternalMsg msg);


  /** This method is used to record a msg that the agent has received
      from another agent. The method may write the msg to a file, send
      it to some msg logging agent, etc. It may also perform no logging
      directly if the instantiated logging facility creates its own
      thread and has an associated external logging agent to which it
      sends msgs for logging. With this arrangement, the logging agent
      can send cmds to the logging facility's thread to control logging
      activity with its own agreed upon set of cmds such as suspend/resume
      logging of msgs. Return true on success, false otherwise.
  */
  public boolean logMsgRcvdByAgent(InternalMsg msg);

	
  /** This method will be called by the Communicator when the agent
      comes up and announces the agent birth to the logging facility
      to mark the beginning of the msg log. Return true on success, false
      otherwise.
  */
  public boolean logAgentBirth();

	
  /** This method will be called through the Communicator by the agent or
      application using the Communicator to log transitions in the state
      of the agent or application. In an agent, especially a multithreaded
      one, it allows for the activities of the various components of the
      agent to record their activities. This is usefule in tracing or in
      displaying the type and patterns of activities that the agent performs.
  */
  public boolean logAgentState(String component, String state);


  /** This method will be called by the Communicator when the agent
      terminates and announces the agent death to the logging facility
      to mark the ending of the msg log. Return true on success, false
      otherwise.
  */
  public boolean logAgentDeath();


  /** This method returns the name of the logging facility.
  */
  public String getLogFacilityName();


  /** This method returns the name of the external logging agent to
      which the log msgs are sent. If there is no associated logging
      agent, null is returned. This method is used by the Communicator
      to discover the names of all logging agents so it can avoid the
      viscious cycle of performing logging of msgs sent to logging agents.
      The Communicator will not log msgs to/from any logging agent.
  */
  public String getLoggingAgentName();



}