001    // Copyright 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    
015    package org.apache.tapestry.asset;
016    
017    import java.util.Locale;
018    
019    import org.apache.hivemind.Location;
020    import org.apache.hivemind.Resource;
021    import org.apache.tapestry.IAsset;
022    
023    /**
024     * Used to create an {@link org.apache.tapestry.IAsset} instance for a particular asset path. The
025     * path may have a prefix that indicates its type, or it may be relative to some existing resource.
026     * 
027     * @author Howard M. Lewis Ship
028     * @since 4.0
029     */
030    public interface AssetSource
031    {
032        /**
033         * Finds an asset relative to some existing resource (typically, a page, component or library
034         * specification).
035         * 
036         * @param base
037         *            the base resource used for resolving the asset
038         * @param path
039         *            the path relative to the base resource; alternately, the path may include a prefix
040         *            that defines a domain (such as "classpath:" or "context:") in which case the base
041         *            resource is ignored and the resource resolved within that domain
042         * @param locale
043         *            used to find a localized version of the asset, may be null to indicate no
044         *            localization
045         * @param location
046         *            used to report errors (such as missing resources)
047         * @return the asset, possibly localized
048         * @throws org.apache.hivemind.ApplicationRuntimeException
049         *             if the asset does not exist
050         */
051        public IAsset findAsset(Resource base, String path, Locale locale, Location location);
052    }