/*
 * Copyright (C) 1998-2002 <a href="mailto:mandarax@jbdietrich.com">Jens Dietrich</a>
 *
 * This library 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 of the License, or (at your option) any later version.
 *
 * This library 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 library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package org.mandarax.kernel;

import java.util.Map;
/**
 * Object representing a session. A session is initiated when the query is issued and terminated when the 
 * inference engine returns the result set.
 * @author <A HREF="mailto:mandarax@jbdietrich.com">Jens Dietrich</A>
 * @version 3.3.1 <9 August 2004>
 * @since 3.2
 */
public interface Session {

	
	/**
	 * Get a unique session id.
	 * @return a session id
	 */
	public Object getId();
	/**
	 * Set (bind) a session attribute.
	 * @param attrName the attribute name
	 * @param attrValue an attribute value
	 */
	public void setAttribute(Object attrName,Object attrValue);
	/**
	 * Get (lookup) a session attribute.
	 * @param attrName the attribute name
	 * @return the attribute value (null indicates that there was no registered value.
	 */
	public Object getAttribute(Object attrName);
	/**
	 * Get the knowledge base used in this session.
	 * @return a knowledge base
	 */
	public KnowledgeBase getKnowledgeBase() ;
	/**
	 * Get the inference engine used in this session.
	 * @return an inference engine
	 */ 
	public InferenceEngine getInferenceEngine();
	/**
	 * Get the query for this session.
	 * @return a query
	 */
	public Query getQuery();
	/**
	 * Get the exception handling strategy used in this session.
	 * @return an integer
	 * @see InferenceEngine.BUBBLE_EXEPTIONS
	 * @see InferenceEngine.TRY_NEXT
	 */
	public int getExceptionHandlingStrategy() ;
	/**
	 * Get the cardinality constraints for this session.
	 * @return an integer
	 * @see InferenceEngine.ALL
	 */
	public int getCardinalityContraint() ;
	/**
	 * Get a map containing the current query variable replacements. 
	 * I.e., the map contains association VariableTerm -> ConstantTerm
	 * @return a map
	 */
	public Map getVariableReplacements();
	
}
