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
015package org.apache.tapestry.engine;
016
017import java.io.IOException;
018
019import 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
030public 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}