/*
 * $Id: PlugIn.java 54929 2004-10-16 16:38:42Z germuska $ 
 *
 * Copyright 2000-2004 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.struts.action;


import javax.servlet.ServletException;
import org.apache.struts.config.ModuleConfig;


/**
 * <p>A <strong>PlugIn</strong> is a configuration wrapper for a
 * module-specific resource or service that needs to be notified about
 * application startup and application shutdown events (corresponding to when
 * the container calls <code>init</code> and <code>destroy</code> on the
 * corresponding {@link ActionServlet} instance). <code>PlugIn</code> objects can be
 * configured in the <code>struts-config.xml</code> file, without the need
 * to subclass {@link ActionServlet} simply to perform application lifecycle
 * activities.</p>
 *
 * <p>Implementations of this interface must supply a zero-argument constructor
 * for use by {@link ActionServlet}. Configuration can be accomplished by
 * providing standard JavaBeans property setter methods, which will all have
 * been called before the <code>init()</code> method is invoked.</p>
 *
 * <p>This interface can be applied to any class, including an Action subclass</p>
 *
 * @version $Rev: 54929 $ $Date: 2004-10-16 09:38:42 -0700 (Sat, 16 Oct 2004) $
 * @since Struts 1.1
 */

public interface PlugIn {


    /**
     * <p>Receive notification that our owning module is being
     * shut down.</p>
     */
    void destroy();


    /**
     * <p>Receive notification that the specified module is being
     * started up.</p>
     *
     * @param servlet ActionServlet that is managing all the
     *  modules in this web application
     * @param config ModuleConfig for the module with which
     *  this plug-in is associated
     *
     * @exception ServletException if this <code>PlugIn</code> cannot
     *  be successfully initialized
     */
    void init(ActionServlet servlet, ModuleConfig config)
        throws ServletException;


}