    001// Copyright 2010 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.tapestry5.services.linktransform;
    016
    017import org.apache.tapestry5.Link;
    018import org.apache.tapestry5.internal.services.PageRenderDispatcher;
    019import org.apache.tapestry5.ioc.annotations.UsesOrderedConfiguration;
    020import org.apache.tapestry5.services.ComponentEventLinkEncoder;
    021import org.apache.tapestry5.services.LocalizationSetter;
    022import org.apache.tapestry5.services.PageRenderRequestParameters;
    023import org.apache.tapestry5.services.Request;
    024
    025/**
    026 * Allows the default {@link Link} for a page render request to be replaced.
    027 * This is a service, but also the contribution to the service, as a chain of command.
    028 * <p>
    029 * A contributed implementation of this interface is expected to identify which requests it wants to transform. The
    030 * {@link #transformPageRenderLink(Link, PageRenderRequestParameters)} method can return a {@link Link} that is allowed
    031 * to differ from Tapestry normal default. Later, when that request is triggered,
    032 * {@link #decodePageRenderRequest(Request)} is required to reverse the operation, identifying the original parameters
    033 * so that request handling can continue.
    034 *
    035 * @since 5.2.0
    036 */
    037@UsesOrderedConfiguration(PageRenderLinkTransformer.class)
    038public interface PageRenderLinkTransformer
    039{
    040    /**
    041     * Transforms a page render link.
    042     *
    043     * @param defaultLink
    044     *            default Link for this request
    045     * @param parameters
    046     *            that define the request
    047     * @return replacement Link, or null
    048     */
    049    Link transformPageRenderLink(Link defaultLink, PageRenderRequestParameters parameters);
    050
    051    /**
    052     * Attempts to decode the page render request, to perform the opposite action for
    053     * {@link #transformPageRenderLink(Link, PageRenderRequestParameters)}. The transformer
    054     * is also responsible for identifying the locale in the request (as part of the path, or as a
    055     * query parameter or cookie) and setting the locale for the request.
    056     * <p>
    057     * This method will be invoked from the {@link PageRenderDispatcher} and a non-null value returned from this method
    058     * will prevent the default {@link ComponentEventLinkEncoder#decodePageRenderRequest(Request)} method from being
    059     * invoked.
    060     *
    061     * @return decoded parameters, or null to proceed normally
    062     * @see LocalizationSetter#setLocaleFromLocaleName(String)
    063     */
    064    PageRenderRequestParameters decodePageRenderRequest(Request request);
    065}