/*
    * Copyright 2000-2002,2004 The Apache Software Foundation.
    * 
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    * 
    *      http://www.apache.org/licenses/LICENSE-2.0
    * 
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  // package
  package org.apache.jetspeed.services.statemanager;
  
  // imports
  import javax.servlet.http.HttpSession;
  
  /***
  * <p>The StateManagerService is a service that manages SessionState information.
  * Each SessionState is identified by a unique key in this service.  The SessionState
  * is composed of name - value sets of attributes, stored under the key by the service.</p>
  * <p>See the proposal: jakarta-jetspeed/proposals/StateManager.txt for more details.</p>
  * <p>Attribute values placed into SessionStates may be automatically removed, for example when
  * a SessionState expires in some way, or by means of some other automatic service.  These value
  * objects can be notified of their placement into and out of the SessionState.  Objects that wish
  * to receive this notification implement the SessionStateBindingListener interface.  This is based
  * on and similar to the HttpSessionBindingListener mechanism.</p>
  * <p>To support the "current" routines; the ability to get a session state based
  * on the current http session, this service must be installed properly into the
  * procssing of each http request.  At the start of the request, the HttpSession
  * of the request must be passed into the setCurrentContext() method.  At the end
  * of the request, clearCurrentContext() is called.  For Jetspeed, this is done in
  * the JetspeedRunDataService, which is always going to be called by Turbine in this
  * way.</p>
  * @version $Revision: 1.5 $
  * @see org.apache.jetspeed.services.statemanager.SessionState
  * @see org.apache.jetspeed.services.statemanager.SessionStateBindingListener
  * @author <a href="mailto:ggolden@apache.org">Glenn R. Golden</a>
  */
  public interface StateManagerService
  {
      /*** The name used to find the service in the service manager. */
      public String SERVICE_NAME = "StateManagerService";
  
      /***
      * Access the named attribute of the keyed state.
      * @param key The state key.
      * @param name The attribute name.
      * @return The named attribute value of the keyed state.
      */
      public Object getAttribute ( String key, String name );
  
      /***
      * Set the named state attribute of the keyed state with the provided object.
      * @param key The state key.
      * @param name The attribute name.
      * @param value The new value of the attribute (any object type).
      */
      public void setAttribute( String key, String name, Object value );
  
      /***
      * Remove the named state attribute of the keyed state, if it exists.
      * @param key The state key.
      * @param name The attribute name.
      */
      public void removeAttribute( String key, String name );
  
      /***
      * Remove all state attribute of the keyed state.
      * @param key The state key.
      */
      public void clear( String key );
  
      /***
      * Access an array of all names of attributes stored in the keyed state.
      * @param key The state key.
      * @return An array of all names of attributes stored in the keyed state.
      */
      public String[] getAttributeNames( String key );
  
      /***
      * Access an SessionState object with the given key.
      * @param key The SessionState key.
      * @return an SessionState object with the given key.
      */
      public SessionState getSessionState( String key );
  
      /***
      * Access the SessionState object associated with the current request's http session.
  	* The session id is used as the key.
      * @return an SessionState object associated with the current request's http session.
      */
      public SessionState getCurrentSessionState();
  
     /***
     * Access the SessionState object associated with the current request's http session with the given key.
 	* @param key The string to add to the session id to form the SessionState key.
     * @return an SessionState object associated with the current request's http session with the given key.
     */
     public SessionState getCurrentSessionState( String key );
 
     /***
     * Retire, forget about and clean up all states that start with the given key.
     * @param keyStart The beginning of the key of the states to clean up.
     */
     public void retireState( String keyStart );
 
     /***
     * Set the "current" context for this thread -
     * Call this at the start of each request, and call %%% at the end.
     * getCurrentSession() uses this for the session state key.
     * @param session the HttpSession of the current request.
     */
     public void setCurrentContext( HttpSession session );
 
     /***
     * Clear the "current context for this thread -
     * Call at the end of each request, balanced with calls to setCurrentContext()
     */
     public void clearCurrentContext();
 
 }   // interface StateManagerService
 
 /***********************************************************************************
 *
 * $Header: /home/cvs/jakarta-jetspeed/src/java/org/apache/jetspeed/services/statemanager/StateManagerService.java,v 1.5 2004/02/23 03:38:28 jford Exp $
 *
 **********************************************************************************/