event.java

来自「jetspeed源代码」· Java 代码 · 共 123 行

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 *       "This product includes software developed by the
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 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

package org.apache.jetspeed.portlet.event;

import org.apache.jetspeed.portlet.Portlet;
import org.apache.jetspeed.portlet.PortletRequest;
import org.apache.jetspeed.portlet.PortletConfig;

/**
 * The <CODE>Event</CODE> is the base interface for all events
 * that can occur whithin the portlet container. To be informed
 * of events, a listener has to be registered with the respective
 * event source.
 * 
 * <P>
 * The portlet container delivers all events to the respective
 * event listeners (and thereby the portlets) before the content
 * generation is started. Should a listener, while processing the
 * event, find that another event needs to be generated, that
 * event will be queued by the portlet container and delivered
 * at a point of time that is at the discretion of the portlet
 * container. It is only guarantued that it will be deliverd
 * and that it will happen before the content generation phase.
 * </P>
 * <P>
 * This also means, that no further events will be delivered
 * once the content generation phase has started. For example,
 * message cannot be sent from within the service() methods.
 * The resulting message event will not be delivered and
 * essentially discarded.
 * </P>
 * <P>
 * Intelligent portlet containers should provide a cyclic event
 * detection mechanism, so that the portlet container does not
 * come to a screaming halt, if two or more portlets happen
 * to send each other events that are triggered by each other.
 * </P>
 * 
 * @author <A HREF="mailto:[e-mail]">Thomas F. Boehme</A>
 */
public interface Event
{
    /**
     ** Returns the portlet request that has caused this event.
     ** If this event is not triggered by a request,
     ** this methods returns <CODE>null</CODE>.
     **
     ** @return   the portlet request
     **/

    public PortletRequest getRequest ();

    /**
     ** Returns the virtual instance of the portlet
     ** that receives this event.
     **
     ** @return   the virtual instance of the portlet
     **/

    public Portlet getPortlet ();

    /**
     ** Returns the portlet config of the virtual instance
     ** that receives this event.
     **
     ** @return   the portlet config
     **/

    public PortletConfig getConfig ();

}