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