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Java > Open Source Codes > nextapp > echo2 > webrender > Service


1 /*
2  * This file is part of the Echo Web Application Framework (hereinafter "Echo").
3  * Copyright (C) 2002-2005 NextApp, Inc.
4  *
5  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
6  *
7  * The contents of this file are subject to the Mozilla Public License Version
8  * 1.1 (the "License"); you may not use this file except in compliance with
9  * the License. You may obtain a copy of the License at
10  * http://www.mozilla.org/MPL/
11  *
12  * Software distributed under the License is distributed on an "AS IS" basis,
13  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
14  * for the specific language governing rights and limitations under the
15  * License.
16  *
17  * Alternatively, the contents of this file may be used under the terms of
18  * either the GNU General Public License Version 2 or later (the "GPL"), or
19  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
20  * in which case the provisions of the GPL or the LGPL are applicable instead
21  * of those above. If you wish to allow use of your version of this file only
22  * under the terms of either the GPL or the LGPL, and not to allow others to
23  * use your version of this file under the terms of the MPL, indicate your
24  * decision by deleting the provisions above and replace them with the notice
25  * and other provisions required by the GPL or the LGPL. If you do not delete
26  * the provisions above, a recipient may use your version of this file under
27  * the terms of any one of the MPL, the GPL or the LGPL.
28  */
29
30 package nextapp.echo2.webrender;
31
32 import java.io.IOException JavaDoc;
33
34
35 /**
36  * An interface for objects that process <code>Connection</code>s, parsing an
37  * HTTP request and producing an HTTP response. <br>
38  * <br>
39  * Every service is identified by a unique identifier. When the client
40  * browser makes a request of the server and provides the identifier of this
41  * service, its <code>service()</code> method will be invoked. Every request
42  * to an Echo application from a client browser will invoke a service.
43  */
44 public interface Service {
45     
46     /**
47      * A value returned by <code>getVersion()</code> to indicate that a
48      * service should not be cached.
49      */
50     public static final int DO_NOT_CACHE = -1;
51     
52     /**
53      * Returns the unique identifier of this service.
54      *
55      * @return The unique identifier of this service.
56      */
57     public String JavaDoc getId();
58
59     /**
60      * Returns the version of the service to be retrieved. When a service is
61      * requested with an updated version number, a non-cached copy will be used.
62      * <code>getVersion()</code> should return distinct values whenever the
63      * service's content may have changed.
64      *
65      * @return The current version number of the service.
66      */
67     public int getVersion();
68     
69     /**
70      * Services an HTTP request. Information about the HTTP request as well
71      * as methods for issuing a response are available from the provided
72      * Connection object.
73      *
74      * @param conn A <code>Connection</code> object which wraps
75      * <code>HttpServletRequest</code> and
76      * <code>HttpServletResponse</code> objects and provides
77      * access to the facilities of the Echo application container.
78      * @throws IOException in the event of errors related to processing the
79      * HTTP request or producing a response.
80      */
81     public void service(Connection conn)
82     throws IOException JavaDoc;
83 }
84
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