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1   package org.apache.maven.plugin;
2   
3   /*
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *  http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing,
15   * software distributed under the License is distributed on an
16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17   * KIND, either express or implied.  See the License for the
18   * specific language governing permissions and limitations
19   * under the License.
20   */
21  
22  import org.apache.maven.plugin.logging.Log;
23  
24  /**
25   * This interface forms the contract required for <code>Mojos</code> to interact with the <code>Maven</code>
26   * infrastructure.
27   * <br/>
28   * It features an <code>execute()</code> method, which triggers the Mojo's build-process behavior, and can throw
29   * a MojoExecutionException or MojoFailureException if error conditions occur.
30   * <br/>
31   * Also included is the <code>setLog(...)</code> method, which simply allows Maven to inject a logging mechanism which
32   * will allow the Mojo to communicate to the outside world through standard Maven channels.
33   *
34   * @author Jason van Zyl
35   */
36  public interface Mojo
37  {
38      /** The component <code>role</code> hint for Plexus container */
39      String ROLE = Mojo.class.getName();
40  
41      /**
42       * Perform whatever build-process behavior this <code>Mojo</code> implements.
43       * <br/>
44       * This is the main trigger for the <code>Mojo</code> inside the <code>Maven</code> system, and allows
45       * the <code>Mojo</code> to communicate errors.
46       *
47       * @throws MojoExecutionException if an unexpected problem occurs.
48       * Throwing this exception causes a "BUILD ERROR" message to be displayed.
49       * @throws MojoFailureException if an expected problem (such as a compilation failure) occurs.
50       * Throwing this exception causes a "BUILD FAILURE" message to be displayed.
51       */
52      void execute()
53          throws MojoExecutionException, MojoFailureException;
54  
55      /**
56       * Inject a standard <code>Maven</code> logging mechanism to allow this <code>Mojo</code> to communicate events
57       * and feedback to the user.
58       *
59       * @param log a new logger
60       */
61      // TODO: not sure about this here, and may want a getLog on here as well/instead
62      void setLog( Log log );
63  
64      /**
65       * Furnish access to the standard Maven logging mechanism which is managed in this base class.
66       *
67       * @return a log4j-like logger object which allows plugins to create messages at levels of <code>"debug"</code>,
68       * <code>"info"</code>, <code>"warn"</code>, and <code>"error"</code>. This logger is the accepted means to display
69       * information to the user.
70       */
71      Log getLog();
72  }