01: /*
02: * @(#)DeliveryMode.java 1.9 02/04/09
03: *
04: * Copyright 1997-2002 Sun Microsystems, Inc. All Rights Reserved.
05: *
06: * SUN PROPRIETARY/CONFIDENTIAL.
07: * This software is the proprietary information of Sun Microsystems, Inc.
08: * Use is subject to license terms.
09: *
10: */
11:
12: package javax.jms;
13:
14: /** The delivery modes supported by the JMS API are <CODE>PERSISTENT</CODE> and
15: * <CODE>NON_PERSISTENT</CODE>.
16: *
17: * <P>A client marks a message as persistent if it feels that the
18: * application will have problems if the message is lost in transit.
19: * A client marks a message as non-persistent if an occasional
20: * lost message is tolerable. Clients use delivery mode to tell a
21: * JMS provider how to balance message transport reliability with throughput.
22: *
23: * <P>Delivery mode covers only the transport of the message to its
24: * destination. Retention of a message at the destination until
25: * its receipt is acknowledged is not guaranteed by a <CODE>PERSISTENT</CODE>
26: * delivery mode. Clients should assume that message retention
27: * policies are set administratively. Message retention policy
28: * governs the reliability of message delivery from destination
29: * to message consumer. For example, if a client's message storage
30: * space is exhausted, some messages may be dropped in accordance with
31: * a site-specific message retention policy.
32: *
33: * <P>A message is guaranteed to be delivered once and only once
34: * by a JMS provider if the delivery mode of the message is
35: * <CODE>PERSISTENT</CODE>
36: * and if the destination has a sufficient message retention policy.
37: *
38: *
39: *
40: * @version 1.0 - 7 August 1998
41: * @author Mark Hapner
42: * @author Rich Burridge
43: */
44:
45: public interface DeliveryMode {
46:
47: /** This is the lowest-overhead delivery mode because it does not require
48: * that the message be logged to stable storage. The level of JMS provider
49: * failure that causes a <CODE>NON_PERSISTENT</CODE> message to be lost is
50: * not defined.
51: *
52: * <P>A JMS provider must deliver a <CODE>NON_PERSISTENT</CODE> message
53: * with an
54: * at-most-once guarantee. This means that it may lose the message, but it
55: * must not deliver it twice.
56: */
57:
58: static final int NON_PERSISTENT = 1;
59:
60: /** This delivery mode instructs the JMS provider to log the message to stable
61: * storage as part of the client's send operation. Only a hard media
62: * failure should cause a <CODE>PERSISTENT</CODE> message to be lost.
63: */
64:
65: static final int PERSISTENT = 2;
66: }
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