    001// Copyright 2011, 2012 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.assets;
    016
    017import org.apache.tapestry5.ContentType;
    018import org.apache.tapestry5.ioc.Resource;
    019import org.apache.tapestry5.ioc.annotations.UsesMappedConfiguration;
    020
    021import java.io.IOException;
    022import java.util.Set;
    023
    024/**
    025 * Converts {@link Resource}s into {@link StreamableResource}s, and may be responsible for
    026 * {@linkplain ResourceTransformer transforming} resources based on file extension. Contributions map a file extension
    027 * (such as "coffee") to a transformer for that file extension.
    028 * Service decorators added to this service may provide additional processing (compression, minimization, and caching).
    029 *
    030 * @since 5.3
    031 */
    032@UsesMappedConfiguration(ResourceTransformer.class)
    033public interface StreamableResourceSource
    034{
    035    /**
    036     * Given a desired content type, identify which file extensions can be mapped to that extension based on
    037     * contributed {@link ResourceTransformer}s that can
    038     * {@linkplain org.apache.tapestry5.services.assets.ResourceTransformer#getTransformedContentType() produce the content type}
    039     * based for a file with that extension.
    040     *
    041     * @param contentType
    042     *         to search for (just a MIME type, such as "text/javascript")
    043     * @return set of file extension, possibly empty, in no particular order. These are the bare extensions, e.g.,
    044     * "js", "coffee".
    045     * @since 5.4
    046     */
    047    Set<String> fileExtensionsForContentType(ContentType contentType);
    048
    049    /**
    050     * Converts a Resource (which must be non-null and exist) into a streamable resource, along with
    051     * some additional optional behaviors.
    052     *
    053     * @param baseResource
    054     *         the resource to convert
    055     * @param processing
    056     *         defines additional processing after the resource has been read and possibly transformed
    057     * @param dependencies
    058     *         Passed to any {@link ResourceTransformer} to track additional dependencies of the base resource
    059     * @return the contents of the Resource, possibly transformed, in a streamable format.
    060     * @throws IOException
    061     *         if the resource does not exist or a URL for the content is not available
    062     */
    063    StreamableResource getStreamableResource(Resource baseResource, StreamableResourceProcessing processing, ResourceDependencies dependencies)
    064            throws IOException;
    065}