01: /*
02: * This file is part of the Echo Web Application Framework (hereinafter "Echo").
03: * Copyright (C) 2002-2005 NextApp, Inc.
04: *
05: * Version: MPL 1.1/GPL 2.0/LGPL 2.1
06: *
07: * The contents of this file are subject to the Mozilla Public License Version
08: * 1.1 (the "License"); you may not use this file except in compliance with
09: * 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;
33:
34: /**
35: * An interface for objects that process <code>Connection</code>s, parsing an
36: * HTTP request and producing an HTTP response. <br>
37: * <br>
38: * Every service is identified by a unique identifier. When the client
39: * browser makes a request of the server and provides the identifier of this
40: * service, its <code>service()</code> method will be invoked. Every request
41: * to an Echo application from a client browser will invoke a service.
42: */
43: public interface Service {
44:
45: /**
46: * A value returned by <code>getVersion()</code> to indicate that a
47: * service should not be cached.
48: */
49: public static final int DO_NOT_CACHE = -1;
50:
51: /**
52: * Returns the unique identifier of this service.
53: *
54: * @return The unique identifier of this service.
55: */
56: public String getId();
57:
58: /**
59: * Returns the version of the service to be retrieved. When a service is
60: * requested with an updated version number, a non-cached copy will be used.
61: * <code>getVersion()</code> should return distinct values whenever the
62: * service's content may have changed.
63: *
64: * @return The current version number of the service.
65: */
66: public int getVersion();
67:
68: /**
69: * Services an HTTP request. Information about the HTTP request as well
70: * as methods for issuing a response are available from the provided
71: * Connection object.
72: *
73: * @param conn A <code>Connection</code> object which wraps
74: * <code>HttpServletRequest</code> and
75: * <code>HttpServletResponse</code> objects and provides
76: * access to the facilities of the Echo application container.
77: * @throws IOException in the event of errors related to processing the
78: * HTTP request or producing a response.
79: */
80: public void service(Connection conn) throws IOException;
81: }
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