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 $Revision: 1.15 $ $Date: 2004/03/14 06:23:42 $
 * @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;
}
