// Copyright 2009 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.tapestry5.services;

 /**

  * Converts the {@linkplain org.apache.tapestry5.Asset#toClientURL() path (or URI) of an asset} into a new format. This

  * is the <em>hook</em> needed to make use of a <a href="http://en.wikipedia.org/wiki/Content_Delivery_Network">Content

  * Delivery Network</a>.

  * <p/>

  * The default implementation of this is <em>identity</em>, the URI is passed through unchanged. Using a contribution to

  * the {@link org.apache.tapestry5.ioc.services.ServiceOverride} service, you may override the default implementation.

  *

  * @since 5.1.0.0

  */

 public interface AssetPathConverter

 {

     /**

      * Returns true if the converter returns that same converted path for any specific asset path (in which case, the

      * converted asset path may be cached in component instance variables more aggresively). This value should be false

      * if the converted path can vary for the same input path ... that is, if external factors (such as the identity of

      * the user, or information obtained from the request) is involved in generating the final client URI.

      *

      * @return true if invariant (and therefore cachable)

      */

     boolean isInvariant();

     /**

      * Converts the default asset client URI to its final form, ready to be sent to the client. The default asset path

      * is an absolute path (it starts with a leading slash) and incorporates the context path if any.

      *

      * @param assetPath default asset path

      * @return a URI that can be sent to the client

      */

     String convertAssetPath(String assetPath);

 }