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1   /*
2    * Copyright 2004 Sun Microsystems, Inc.
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *     http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   *
16   */
17  package com.sun.syndication.fetcher;
18  
19  import java.io.IOException;
20  import java.net.URL;
21  
22  import com.sun.syndication.feed.synd.SyndFeed;
23  import com.sun.syndication.io.FeedException;
24  
25  public interface FeedFetcher {
26  	/***
27  	 * <p>The default user agent. It is not marked final so
28  	 * buggy java compiler will not write this string
29  	 * into all classes that reference it.</p>
30  	 * 
31  	 * <p>http://tinyurl.com/64t5n points to https://rome.dev.java.net/
32  	 * Some servers ban user agents with "Java" in the name.</p> 
33  	 * 
34  	 */
35  	public static String DEFAULT_USER_AGENT = "Rome Client (http://tinyurl.com/64t5n)";
36  
37  	/***
38  	 * @return the User-Agent currently being sent to servers
39  	 */
40  	public abstract String getUserAgent();
41  	/***
42  	 * @param string The User-Agent to sent to servers
43  	 */
44  	public abstract void setUserAgent(String string);
45  	/***
46  	 * Retrieve a feed over HTTP
47  	 *
48  	 * @param feedUrl A non-null URL of a RSS/Atom feed to retrieve
49  	 * @return A {@link com.sun.syndication.feed.synd.SyndFeed} object
50  	 * @throws IllegalArgumentException if the URL is null;
51  	 * @throws IOException if a TCP error occurs
52  	 * @throws FeedException if the feed is not valid
53  	 * @throws FetcherException if a HTTP error occurred
54  	 */
55  	public abstract SyndFeed retrieveFeed(URL feedUrl)	throws IllegalArgumentException, IOException, FeedException, FetcherException;
56  
57  	/***
58  	 * <p>Add a FetcherListener.</p>
59  	 *
60  	 * <p>The FetcherListener will receive an FetcherEvent when
61  	 * a Fetcher event (feed polled, retrieved, etc) occurs</p>
62  	 *
63  	 * @param listener The FetcherListener to recieve the event
64  	 */
65  	public abstract void addFetcherEventListener(FetcherListener listener);
66  
67  	/***
68  	 * <p>Remove a FetcherListener</p>
69  	 *
70  	 * @param listener The FetcherListener to remove
71  	 */
72  	public abstract void removeFetcherEventListener(FetcherListener listener);
73  
74  	/***
75  	 * <p>Is this fetcher using rfc3229 delta encoding?</p>
76  	 * 
77  	 * @return
78  	 */
79      public abstract boolean isUsingDeltaEncoding();
80  
81      /***
82       * <p>Turn on or off rfc3229 delta encoding</p>
83       * 
84       * <p>See http://www.ietf.org/rfc/rfc3229.txt and http://bobwyman.pubsub.com/main/2004/09/using_rfc3229_w.html</p>
85       * 
86       * <p>NOTE: This is experimental and feedback is welcome!</p>
87       * 
88       * @param useDeltaEncoding
89       */
90      public abstract void setUsingDeltaEncoding(boolean useDeltaEncoding);
91  	
92  }