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    public interface IDirect extends IComponent, IDynamicInvoker
023    {
024        /**
025         *  Invoked by the direct service to have the component perform
026         *  the appropriate action.  The {@link org.apache.tapestry.link.DirectLink} component will
027         *  notify its listener.
028         *
029         * @param cycle
030         *          The current request.
031         */
032        void trigger(IRequestCycle cycle);
033    
034        /**
035         *  Invoked by the direct service to query the component as to
036         *  whether it is stateful.  If stateful and no 
037         *  {@link javax.servlet.http.HttpSession} is active, then a
038         *  {@link org.apache.tapestry.StaleSessionException} is
039         *  thrown by the service.
040         *
041         * @return Whether or not invocation should include state information and validate
042         *          that a valid session exists when triggered.
043         * @since 2.3
044         */
045        boolean isStateful();
046    }