001// Copyright 2013 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;
018
019import java.io.IOException;
020
021/**
022 * Generates a checksum of an arbitrary {@link org.apache.tapestry5.ioc.Resource} or {@link StreamableResource} which can be incorporated into
023 * the {@linkplain org.apache.tapestry5.Asset#toClientURL() client URL} of an Asset.
024 *
025 * @since 5.4
026 */
027public interface AssetChecksumGenerator
028{
029    /**
030     * Given a raw resource, generates an MD5 checksum of the resource's contents.
031     *
032     * @param resource
033     * @return checksum of contents
034     * @throws IOException
035     */
036    String generateChecksum(Resource resource) throws IOException;
037
038    /**
039     * Given a streamable resource, generates an MD5 checksum of the resource's contents.
040     *
041     * @param resource
042     * @return checksum of contents
043     * @throws IOException
044     */
045    String generateChecksum(StreamableResource resource) throws IOException;
046}