001    // Copyright 2004, 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry;
016    
017    /**
018     *  Interface that defines classes that may be messaged by the direct
019     *  service.
020     *
021     *  @author Howard Lewis Ship
022     **/
023    
024    public interface IDirect extends IComponent
025    {
026        /**
027         *  Invoked by the direct service to have the component peform
028         *  the appropriate action.  The {@link org.apache.tapestry.link.DirectLink} component will
029         *  notify its listener.
030         *
031         **/
032    
033        public void trigger(IRequestCycle cycle);
034    
035        /**
036         *  Invoked by the direct service to query the component as to
037         *  whether it is stateful.  If stateful and no 
038         *  {@link javax.servlet.http.HttpSession} is active, then a
039         *  {@link org.apache.tapestry.StaleSessionException} is
040         *  thrown by the service.
041         * 
042         *  @since 2.3
043         * 
044         **/
045    
046        public boolean isStateful();
047    
048    }