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.engine;
016    
017    import java.io.IOException;
018    
019    import org.apache.tapestry.IRequestCycle;
020    
021    /**
022     * A service, provided by the {@link org.apache.tapestry.IEngine}, for its pages and/or components.
023     * Services are responsible for constructing {@link EngineServiceLink}s (an encoding of URLs) to
024     * represent dynamic application behavior, and for parsing those URLs when a subsequent request
025     * involves them.
026     * 
027     * @author Howard Lewis Ship
028     */
029    
030    public interface IEngineService
031    {
032        /**
033         * Builds a URL for a service. This is performed during the rendering phase of one request cycle
034         * and bulds URLs that will invoke activity in a subsequent request cycle.
035         * <p>
036         * <b>This method changed incompatibly between release 3.0 and release 4.0. </b>
037         * </p>
038         * @param post
039         *            if true, then the link will be used for a post (not a get, i.e., for a HTML form);
040         *            this may affect what information is encoded into the link
041         * @param parameter
042         *            An object that provide any additional information needed by the service. Each
043         *            service implementation will expect that an object of the proper type be passed in.
044         *            In some cases, a simple String will do; in others, a specific object (possibly
045         *            implementing an interface) will be required.
046         * 
047         * @return The URL for the service. The URL will have to be encoded via
048         *         {@link javax.servlet.http.HttpServletResponse#encodeURL(java.lang.String)}.
049         */
050    
051        public ILink getLink(boolean post, Object parameter);
052    
053        /**
054         * Perform the service, interpreting the URL (from the
055         * {@link javax.servlet.http.HttpServletRequest}) responding appropriately, and rendering a
056         * result page.
057         * 
058         * @param cycle
059         *            the incoming request
060         * @see org.apache.tapestry.IEngine#service(org.apache.tapestry.request.RequestContext)
061         */
062    
063        public void service(IRequestCycle cycle) throws IOException;
064    
065        /**
066         * Returns the name of the service.
067         * 
068         * @since 1.0.1
069         */
070    
071        public String getName();
072    }