Repository


1   /* 
2    * Copyright 2004 Apache Software Foundation
3    * Licensed  under the  Apache License,  Version 2.0  (the "License");
4    * you may not use  this file  except in  compliance with the License.
5    * You may obtain a copy of the License at 
6    * 
7    *   http://www.apache.org/licenses/LICENSE-2.0
8    * 
9    * Unless required by applicable law or agreed to in writing, software
10   * distributed  under the  License is distributed on an "AS IS" BASIS,
11   * WITHOUT  WARRANTIES OR CONDITIONS  OF ANY KIND, either  express  or
12   * implied.
13   * 
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  package org.apache.avalon.repository;
19  
20  import java.net.URL  ;
21  import javax.naming.directory.Attributes   ;
22  
23  /**
24   * A service that provides access to versioned resources.
25   * @author <a HREF="mailto:dev@avalon.apache.org">Avalon Development Team</a>
26   * @version $Revision: 1.4 $ $Date: 2004/03/04 03:26:41 $
27   */
28  public interface Repository
29  {
30      /**
31       * The context resolution key.
32       */
33      String   KEY = "urn:assembly:repository" ;
34  
35      /**
36       * The seperator character between the group and resource name values
37       * in an artifact name.
38       */
39      String   SEPERATOR = ":" ;
40  
41     /**
42      * Return the metadata of an artifact as attributes.
43      * @param artifact the artifact
44      * @return the attributes resolved relative to the artifact address
45      * @exception RepositoryException if an error occurs while resolving
46      *   artifact metadata attributes
47      */
48      Attributes   getAttributes( Artifact artifact ) 
49          throws RepositoryException ;
50      
51      /**
52       * Get a resource url relative to the supplied artifact.
53       * 
54       * @param artifact the artifact describing the resource
55       * @return the resource url
56       */
57      URL   getResource( Artifact artifact ) throws RepositoryException;
58  
59     /**
60      * Return the set of available artifacts capable of providing the  
61      * supplied service class.
62      *
63      * @return the set of candidate factory artifacts
64      */
65      Artifact[] getCandidates( Class   service );
66  
67      /**
68       * Creates a ClassLoader chain returning the lowest ClassLoader containing 
69       * the jar artifact in the loader's path.  The dependencies of the argument 
70       * artifact jar and an api, spi and implementation attribute on the jar and 
71       * its dependencies are used to construct the ClassLoaders.
72       * 
73       * @param artifact the implementation artifact
74       * @return the lowest ClassLoader in a chain
75       * @throws RepositoryException if there is a problem caching and accessing
76       * repository artifacts and reading their attributes.
77       */
78      ClassLoader   getClassLoader( Artifact artifact )
79          throws RepositoryException ;
80  
81      /**
82       * Creates a ClassLoader chain returning the lowest ClassLoader containing 
83       * the jar artifact in the loader's path.  The dependencies of the argument 
84       * artifact jar and an api, spi and implementation attribute on the jar and 
85       * its dependencies are used to construct the ClassLoaders.
86       * 
87       * @param parent the parent classloader
88       * @param artifact the implementation artifact
89       * @return the lowest ClassLoader in a chain
90       * @throws RepositoryException if there is a problem caching and accessing
91       * repository artifacts and reading their attributes.
92       */
93      ClassLoader   getClassLoader( ClassLoader   parent, Artifact artifact )
94          throws RepositoryException ;
95  }
96
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