/*
* JBoss, Home of Professional Open Source
* Copyright 2005, JBoss Inc., and individual contributors as indicated
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package javax.security.jacc;

/** JACC interface which defines the methods that must be implemented by
 * handlers that are to be registered and activated by PolicyContexts
 * 
 * @see http://java.sun.com/j2ee/1.4/docs/api/
 * 
 * @author Scott.Stark@jboss.org
 * @author Ron Monzillo, Gary Ellison (javadoc)
 * @version $Revision$
 */
public interface PolicyContextHandler
{
   /** Used by the PolicyContext class to activate the handler and obtain from
    * it the context object identified by the given key. In addition
    * to the key, the handler will be activated with the handler data value
    * associated within the PolicyContext class with the thread on which the
    * call to this method is made.
    *
    * @param key - a non-null key indicating which context to return.
    * @param data - the possiblye null handler data Object associated with the
    * thread on which the call to this method has been made.
    * @return The container and handler specific Object  containing the desired
    * context. A null value may be returned if the value of the corresponding
    * context is null.
    * @throws PolicyContextException
    */ 
   public Object getContext(String key, Object data)
      throws PolicyContextException;

   /** Get the keys identifying the context objects supported by this handlers
    * getContext(String, Object) method.
    * The value of each key supported by a handler must be a non-null String
    * value.
    * 
    * @return the list of supported context object keys.
    * @throws PolicyContextException
    */ 
   public String[] getKeys()
      throws PolicyContextException;

   /** Query the handler to see if its getContext(String, Object) method
    * supports the given key.
    * 
    * @param key - the context object key to check.
    * @return true if the key is supported, false otherwise
    * @throws PolicyContextException
    */ 
   public boolean supports(String key)
      throws PolicyContextException;
}
