001// Copyright 2004, 2005 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.tapestry;
016
017import java.io.InputStream;
018
019import org.apache.hivemind.Locatable;
020import org.apache.hivemind.Resource;
021
022/**
023 * Representation of a asset (GIF, JPEG, etc.) that may be owned by a {@link IComponent}.
024 * <p>
025 * Assets may be completely external (i.e., on some other web site), contained by the
026 * {@link javax.servlet.ServletContext}, or stored somewhere in the classpath.
027 * <p>
028 * In the latter two cases, the resource may be localized.
029 * 
030 * @author Howard Lewis Ship
031 */
032
033public interface IAsset extends Locatable
034{
035    /**
036     * Returns a URL for the asset, ready to be inserted into the output HTML. If the asset can be
037     * localized, the localized version (matching the {@link java.util.Locale}of the current
038     * {@link IPage page}) is returned.
039     * 
040     * @throws ApplicationRuntimeException
041     *             if the asset does not exist.
042     */
043
044    public String buildURL();
045
046    /**
047     * Accesses the localized version of the resource (if possible) and returns it as an input
048     * stream. A version of the resource localized to the current {@link IPage page}is returned.
049     * 
050     * @throws ApplicationRuntimeException
051     *             if the asset does not exist, or can't be read.
052     */
053
054    public InputStream getResourceAsStream();
055
056    /**
057     * Returns the underlying location of the asset.
058     */
059
060    public Resource getResourceLocation();
061}