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 org.apache.hivemind.Location;
018    import org.apache.hivemind.Resource;
019    import org.apache.tapestry.IAsset;
020    import org.apache.tapestry.spec.IComponentSpecification;
021    
022    import java.util.Locale;
023    
024    /**
025     * Used to create an {@link org.apache.tapestry.IAsset} instance for a particular asset path. The
026     * path may have a prefix that indicates its type, or it may be relative to some existing resource.
027     * 
028     * @author Howard M. Lewis Ship
029     * @since 4.0
030     */
031    public interface AssetSource
032    {
033        /**
034         * Finds an asset relative to some existing resource (typically, a page, component or library
035         * specification).
036         * 
037         * @param base
038         *            The base resource used for resolving the asset
039         * @param path
040         *            the path relative to the base resource; alternately, the path may include a prefix
041         *            that defines a domain (such as "classpath:" or "context:") in which case the base
042         *            resource is ignored and the resource resolved within that domain
043         * @param locale
044         *            used to find a localized version of the asset, may be null to indicate no
045         *            localization
046         * @param location
047         *            used to report errors (such as missing resources)
048         *            
049         * @return the asset, possibly localized
050         * 
051         * @throws org.apache.hivemind.ApplicationRuntimeException
052         *             if the asset does not exist
053         */
054        IAsset findAsset(Resource base, String path, Locale locale, Location location);
055    
056        /**
057         * Finds an asset relative to the specified <code>base</code> resources OR {@link IComponentSpecification} passed in.
058         *
059         * @param base
060         *            The base resource used for resolving the asset
061         * @param spec
062         *            The specification the resource may be relative to if not found relative to base.
063         * @param path
064         *            the path relative to the base resource; alternately, the path may include a prefix
065         *            that defines a domain (such as "classpath:" or "context:") in which case the base
066         *            resource is ignored and the resource resolved within that domain
067         * @param locale
068         *            used to find a localized version of the asset, may be null to indicate no
069         *            localization
070         * @param location
071         *            used to report errors (such as missing resources)
072         *
073         * @return the asset, possibly localized
074         */
075        IAsset findAsset(Resource base, IComponentSpecification spec, String path, Locale locale, Location location);
076    }