    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}