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    
015    package org.apache.tapestry5.services.assets;
016    
017    import org.apache.tapestry5.ioc.Resource;
018    import org.apache.tapestry5.ioc.annotations.UsesMappedConfiguration;
019    
020    import 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)
030    public 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    }