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 * 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 org.jboss.ha.framework.interfaces;

import org.jboss.invocation.Invocation;

/**
 * Base interface for load-balancing policies. It is possible to implement many
 * different load-balancing policies by implementing this simple interface and
 * using it in the different clustered services (home interface of SLSB for
 * example)
 *
 * @author <a href="mailto:bill@burkecentral.com">Bill Burke</a>.
 * @author <a href="mailto:sacha.labourey@cogito-info.ch">Sacha Labourey</a>.
 * @version $Revision: 1.3.4.5 $
 */
public interface LoadBalancePolicy extends java.io.Serializable
{
   /** The serialVersionUID
    * @since 1.3.4.2
    */ 
   static final long serialVersionUID = -5071668971774090555L;
   /**
    * Initialize the policy with a reference to its parent stub. the load-balancing policy
    * implementation can use HARMIClient data to take its decision
    * @param father The stub that owns the policy
    */   
   public void init (HARMIClient father);

   /**
    * Called when the stub wishes to know on which node the next invocation must
    * be performed.
    * @param clusterFamily A list of potential target nodes
    * @return The selected target for the next invocation
    */   
   public Object chooseTarget (FamilyClusterInfo clusterFamily);

   /**
    * Called when the stub wishes to know on which node the next invocation must
    * be performed.
    * @param clusterFamily A list of potential target nodes
    * @param routingDecision The actual invocation object if the policy wants
    * to have some kind of invocation-based routing strategy
    * @return The selected target for the next invocation
    */   
   public Object chooseTarget (FamilyClusterInfo clusterFamily, Invocation routingDecision);
}
