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    /**
019     *  Interface that defines classes that may be messaged by the direct
020     *  service.
021     *
022     *  @author Howard Lewis Ship
023     **/
024    
025    public interface IDirect extends IComponent, IDynamicInvoker
026    {
027        /**
028         *  Invoked by the direct service to have the component peform
029         *  the appropriate action.  The {@link org.apache.tapestry.link.DirectLink} component will
030         *  notify its listener.
031         *
032         */
033    
034        void trigger(IRequestCycle cycle);
035    
036        /**
037         *  Invoked by the direct service to query the component as to
038         *  whether it is stateful.  If stateful and no 
039         *  {@link javax.servlet.http.HttpSession} is active, then a
040         *  {@link org.apache.tapestry.StaleSessionException} is
041         *  thrown by the service.
042         * 
043         *  @since 2.3
044         * 
045         */
046    
047        boolean isStateful();
048    }