001// Copyright 2006, 2008, 2010, 2011, 2013 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;
016
017import org.apache.tapestry5.internal.services.assets.ClasspathAssetRequestHandler;
018import org.apache.tapestry5.ioc.Resource;
019import org.apache.tapestry5.ioc.annotations.IncompatibleChange;
020import org.apache.tapestry5.ioc.annotations.UsesMappedConfiguration;
021
022import java.util.Map;
023
024/**
025 * Used as part of the support for classpath {@link org.apache.tapestry5.Asset}s, to convert the Asset's
026 * {@link org.apache.tapestry5.ioc.Resource} to a URL that can be accessed by the client. The asset path, within the
027 * classpath, is converted into a shorter virtual path. The term "alias" here is generally referred to as
028 * "virtual folder" elsewhere.
029 * <p/>
030 * Service configuration is a map from folder aliases (short names) to complete paths. Names should not start or end end
031 * with a slash. Generally, an alias should be a single name (not contain a slash). Paths should also not start or end
032 * with a slash. An example mapping would be <code>mylib</code> to <code>com/example/mylib</code>.
033 * <p/>
034 * As originally envisioned, this service would simply <em>optimize</em> classpath assets, allowing the URL path for
035 * such assets to be shortened (and have a version number added, important for caching); thus the word "alias" makes
036 * sense ... it was responsible for creating an "alias" URL shorter than the default "classpath" URL.
037 * <p/>
038 * Starting in Tapestry 5.2, this changed; all classpath assets <strong>must</strong> be "aliased" to a shorter URL
039 * path. Any URL that can not be shortened is now rejected. This simplifies creating new libraries, but also helps with
040 * security concerns, as it limits which portions of the classpath can <em>ever</em> be exposed to the user agent.
041 * <p/>
042 * Tapestry automatically contributes a number of mappings: for the application root package itself (as alias "app") and
043 * for each library (via {@link ComponentClassResolver#getFolderToPackageMapping()});
044 *
045 * @deprecated Deprecated in 5.4, with no replacement. This will no longer be used in Tapestry 5.5, as all classpath assets
046 *             will need to be under the {@code META-INF/assets} folder (but may be maintained for compatibility reasons until 5.6).
047 */
048@UsesMappedConfiguration(String.class)
049public interface ClasspathAssetAliasManager
050{
051    /**
052     * Takes a classpath resource and determines the proper alias for it based on the mappings contributed to the service.
053     *
054     * @param resource
055     *         classpath resource
056     * @return URL ready to send to the client
057     */
058    @IncompatibleChange(release = "5.4", details = "parameter changed from String to Resource, renamed from toClientURL() to better identify purpose")
059    AssetAlias extractAssetAlias(Resource resource);
060
061    /**
062     * Returns the mappings used by the service: the keys are the folder aliases (i.e, "corelib")
063     * and the values are the corresponding paths (i.e., "org/apache/tapestry5/corelib"). This
064     * exists primarily so that {@link ClasspathAssetRequestHandler}s can be created automatically
065     * for each mapping.
066     *
067     * @since 5.2.0
068     */
069    Map<String, String> getMappings();
070}