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    
015    package org.apache.tapestry5.services.linktransform;
016    
017    import org.apache.tapestry5.Link;
018    import org.apache.tapestry5.internal.services.ComponentEventDispatcher;
019    import org.apache.tapestry5.ioc.annotations.UsesOrderedConfiguration;
020    import org.apache.tapestry5.services.ComponentEventRequestParameters;
021    import org.apache.tapestry5.services.LocalizationSetter;
022    import org.apache.tapestry5.services.Request;
023    
024    /**
025     * Allows for selective replacement of the default {@link Link} used to represent a component event request.
026     * This is a service, but also the contribution to the service, as a chain of command.
027     * <p>
028     * This transformer follows the same pattern as {@link PageRenderLinkTransformer}.
029     * 
030     * @since 5.2.0
031     */
032    @UsesOrderedConfiguration(ComponentEventLinkTransformer.class)
033    public interface ComponentEventLinkTransformer
034    {
035        /**
036         * Allows the default Link created for the component event request to be replaced.
037         * 
038         * @param defaultLink
039         *            the default Link generated for a component event request
040         * @param parameters
041         *            used to create the default Link
042         * @return a replacement Link, or null
043         */
044        Link transformComponentEventLink(Link defaultLink, ComponentEventRequestParameters parameters);
045    
046        /**
047         * Attempts to decode the page render request, to perform the opposite action for
048         * {@link #transformComponentEventLink(Link, ComponentEventRequestParameters)}. The transformer
049         * is also responsible for identifying the locale in the request (as part of the path, or as a
050         * query parameter or cookie) and setting the locale for the request.
051         * <p>
052         * This method will be invoked from the {@link ComponentEventDispatcher} and a non-null value returned from this
053         * method will prevent the default
054         * {@link org.apache.tapestry5.services.ComponentEventLinkEncoder#decodeComponentEventRequest(Request)} method
055         * from being invoked.
056         * 
057         * @return decoded parameters, or null to proceed normally
058         * @see LocalizationSetter#setLocaleFromLocaleName(String)
059         */
060        ComponentEventRequestParameters decodeComponentEventRequest(Request request);
061    }