// Copyright 2006 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package org.apache.tapestry.internal.services;
import org.apache.tapestry.internal.event.InvalidationEventHub;
import org.apache.tapestry.ioc.Resource;
import org.apache.tapestry.services.ResourceDigestGenerator;
/**
* Caches information about resources on the classpath. In addition, acts as an invalidation hub for
* any resources for which information is obtained (when any of the resources are changed,
* invalidation listeners are notified so they can clear their caches).
*/
public interface ResourceCache extends InvalidationEventHub
{
/**
* Returns true if the path requires that the client URL for the resource include a digest to
* validate that the client is authorized to access the resource.
*
* @param resource
* @return true if digest is required for the resource
* @see ResourceDigestGenerator#requiresDigest(String)
*/
boolean requiresDigest(Resource resource);
/**
* Returns the digest for the given path.
*
* @param resource
* @return the digest, or null if the resource does not exist
*/
String getDigest(Resource resource);
/**
* Returns the time modified for the resource.
*
* @param resource
* @return the date time modified for the path, or a negative value if the resource does not
* exist
*/
long getTimeModified(Resource resource);
}
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