001// Copyright 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.assets;
016
017import org.apache.tapestry5.ioc.Resource;
018import org.apache.tapestry5.ioc.annotations.UsesMappedConfiguration;
019
020import java.io.IOException;
021
022/**
023 * Converts {@link Resource}s into {@link StreamableResource}s, and may be responsible for
024 * {@linkplain ResourceTransformer transforming} resources based on file extension. In addition,
025 * service decorators added to the service may provide additional processing (compression, minimization, and caching).
026 *
027 * @since 5.3
028 */
029@UsesMappedConfiguration(ResourceTransformer.class)
030public interface StreamableResourceSource
031{
032    /**
033     * Converts a Resource (which must be non-null and exist) into a streamable resource, along with
034     * some additional optional behaviors.
035     *
036     * @param baseResource the resource to convert
037     * @param processing   defines additional processing after the resource has been read and possibly transformed
038     * @param dependencies Passed to any {@link ResourceTransformer} to track additional dependencies of the base resource
039     * @return the contents of the Resource, possibly transformed, in a streamable format.
040     * @throws IOException if the resource does not exist or a URL for the content is not available
041     */
042    StreamableResource getStreamableResource(Resource baseResource, StreamableResourceProcessing processing, ResourceDependencies dependencies)
043            throws IOException;
044}