/* * @(#)DeliveryMode.java	1.9 02/04/09 * * Copyright 1997-2002 Sun Microsystems, Inc. All Rights Reserved. * *  SUN PROPRIETARY/CONFIDENTIAL. * This software is the proprietary information of Sun Microsystems, Inc.   * Use is subject to license terms. *  */package javax.jms;/** The delivery modes supported by the JMS API are <CODE>PERSISTENT</CODE> and  * <CODE>NON_PERSISTENT</CODE>.  *  * <P>A client marks a message as persistent if it feels that the   * application will have problems if the message is lost in transit.  * A client marks a message as non-persistent if an occasional  * lost message is tolerable. Clients use delivery mode to tell a  * JMS provider how to balance message transport reliability with throughput.  *  * <P>Delivery mode covers only the transport of the message to its   * destination. Retention of a message at the destination until  * its receipt is acknowledged is not guaranteed by a <CODE>PERSISTENT</CODE>   * delivery mode. Clients should assume that message retention   * policies are set administratively. Message retention policy  * governs the reliability of message delivery from destination  * to message consumer. For example, if a client's message storage   * space is exhausted, some messages may be dropped in accordance with   * a site-specific message retention policy.  *  * <P>A message is guaranteed to be delivered once and only once  * by a JMS provider if the delivery mode of the message is   * <CODE>PERSISTENT</CODE>   * and if the destination has a sufficient message retention policy.  *  *  *  * @version     1.0 - 7 August 1998  * @author      Mark Hapner  * @author      Rich Burridge  */public interface DeliveryMode {    /** This is the lowest-overhead delivery mode because it does not require       * that the message be logged to stable storage. The level of JMS provider      * failure that causes a <CODE>NON_PERSISTENT</CODE> message to be lost is       * not defined.      *      * <P>A JMS provider must deliver a <CODE>NON_PERSISTENT</CODE> message       * with an       * at-most-once guarantee. This means that it may lose the message, but it       * must not deliver it twice.      */    static final int NON_PERSISTENT = 1;    /** This delivery mode instructs the JMS provider to log the message to stable       * storage as part of the client's send operation. Only a hard media       * failure should cause a <CODE>PERSISTENT</CODE> message to be lost.      */    static final int PERSISTENT = 2;}