    001// Licensed under the Apache License, Version 2.0 (the "License");
    002// you may not use this file except in compliance with the License.
    003// You may obtain a copy of the License at
    004//
    005// http://www.apache.org/licenses/LICENSE-2.0
    006//
    007// Unless required by applicable law or agreed to in writing, software
    008// distributed under the License is distributed on an "AS IS" BASIS,
    009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    010// See the License for the specific language governing permissions and
    011// limitations under the License.
    012
    013package org.apache.tapestry5.services;
    014
    015import org.apache.tapestry5.commons.Resource;
    016import org.apache.tapestry5.internal.services.assets.ClasspathAssetRequestHandler;
    017import org.apache.tapestry5.ioc.annotations.IncompatibleChange;
    018import org.apache.tapestry5.ioc.annotations.UsesMappedConfiguration;
    019
    020import java.util.Map;
    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.commons.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 *
    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 *
    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 *
    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 *
    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 * @deprecated Deprecated in 5.4, with no replacement. This will no longer be used in Tapestry 5.5, as all classpath assets
    044 *             will need to be under the {@code META-INF/assets} folder (but may be maintained for compatibility reasons until 5.6).
    045 */
    046@UsesMappedConfiguration(String.class)
    047public interface ClasspathAssetAliasManager
    048{
    049    /**
    050     * Takes a classpath resource and determines the proper alias for it based on the mappings contributed to the service.
    051     *
    052     * @param resource
    053     *         classpath resource
    054     * @return URL ready to send to the client
    055     */
    056    @IncompatibleChange(release = "5.4", details = "parameter changed from String to Resource, renamed from toClientURL() to better identify purpose")
    057    AssetAlias extractAssetAlias(Resource resource);
    058
    059    /**
    060     * Returns the mappings used by the service: the keys are the folder aliases (i.e, "corelib")
    061     * and the values are the corresponding paths (i.e., "org/apache/tapestry5/corelib"). This
    062     * exists primarily so that {@link ClasspathAssetRequestHandler}s can be created automatically
    063     * for each mapping.
    064     *
    065     * @since 5.2.0
    066     */
    067    Map<String, String> getMappings();
    068}