/*
 * Copyright 1999,2004 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 org.apache.catalina;

import java.io.IOException;
import java.net.URL;
/**
 * A <b>Cluster</b> works as a Cluster client/server for the local host
 * Different Cluster implementations can be used to support different
 * ways to communicate within the Cluster. A Cluster implementation is
 * responsible for setting up a way to communicate within the Cluster
 * and also supply "ClientApplications" with <code>ClusterSender</code>
 * used when sending information in the Cluster and
 * <code>ClusterInfo</code> used for receiving information in the Cluster.
 *
 * @author Bip Thelin
 * @author Remy Maucherat
 * @author Filip Hanik
 * @version $Revision$, $Date$
 */

public interface Cluster {

    // ------------------------------------------------------------- Properties

    /**
     * Return descriptive information about this Cluster implementation and
     * the corresponding version number, in the format
     * <code>&lt;description&gt;/&lt;version&gt;</code>.
     */
    public String getInfo();

    /**
     * Return the name of the cluster that this Server is currently
     * configured to operate within.
     *
     * @return The name of the cluster associated with this server
     */
    public String getClusterName();

    /**
     * Set the name of the cluster to join, if no cluster with
     * this name is present create one.
     *
     * @param clusterName The clustername to join
     */
    public void setClusterName(String clusterName);

    /**
     * Set the Container associated with our Cluster
     *
     * @param container The Container to use
     */
    public void setContainer(Container container);

    /**
     * Get the Container associated with our Cluster
     *
     * @return The Container associated with our Cluster
     */
    public Container getContainer();

    /**
     * Set the protocol parameters.
     *
     * @param protocol The protocol used by the cluster
     * @deprecated
     */
    public void setProtocol(String protocol);

    /**
     * Get the protocol used by the cluster.
     *
     * @return The protocol
     * @deprecated
     */
    public String getProtocol();

    // --------------------------------------------------------- Public Methods

    /**
     * Create a new manager which will use this cluster to replicate its
     * sessions.
     *
     * @param name Name (key) of the application with which the manager is
     * associated
     */
    public Manager createManager(String name);

    // --------------------------------------------------------- Cluster Wide Deployments
    
    
    /**
     * Execute a periodic task, such as reloading, etc. This method will be
     * invoked inside the classloading context of this container. Unexpected
     * throwables will be caught and logged.
     */
    public void backgroundProcess();


    /**
     * Start an existing web application, attached to the specified context
     * path in all the other nodes in the cluster.
     * Only starts a web application if it is not running.
     *
     * @param contextPath The context path of the application to be started
     *
     * @exception IllegalArgumentException if the specified context path
     *  is malformed (it must be "" or start with a slash)
     * @exception IllegalArgumentException if the specified context path does
     *  not identify a currently installed web application
     * @exception IOException if an input/output error occurs during
     *  startup
     * @deprecated
     */
    public void startContext(String contextPath) throws IOException;


    /**
     * Install a new web application, whose web application archive is at the
     * specified URL, into this container with the specified context path.
     * A context path of "" (the empty string) should be used for the root
     * application for this container.  Otherwise, the context path must
     * start with a slash.
     * <p>
     * If this application is successfully installed, a ContainerEvent of type
     * <code>PRE_INSTALL_EVENT</code> will be sent to registered listeners
     * before the associated Context is started, and a ContainerEvent of type
     * <code>INSTALL_EVENT</code> will be sent to all registered listeners
     * after the associated Context is started, with the newly created
     * <code>Context</code> as an argument.
     *
     * @param contextPath The context path to which this application should
     *  be installed (must be unique)
     * @param war A URL of type "jar:" that points to a WAR file, or type
     *  "file:" that points to an unpacked directory structure containing
     *  the web application to be installed
     *
     * @exception IllegalArgumentException if the specified context path
     *  is malformed (it must be "" or start with a slash)
     * @exception IllegalStateException if the specified context path
     *  is already attached to an existing web application
     * @deprecated
     */
    public void installContext(String contextPath, URL war);

    /**
     * Stop an existing web application, attached to the specified context
     * path.  Only stops a web application if it is running.
     *
     * @param contextPath The context path of the application to be stopped
     *
     * @exception IllegalArgumentException if the specified context path
     *  is malformed (it must be "" or start with a slash)
     * @exception IllegalArgumentException if the specified context path does
     *  not identify a currently installed web application
     * @exception IOException if an input/output error occurs while stopping
     *  the web application
     * @deprecated
     */
    public void stop(String contextPath) throws IOException;


}