Author: timfox Date: 2009-09-09 09:42:27 -0400 (Wed, 09 Sep 2009) New Revision: 7945 Modified: trunk/docs/user-manual/en/pre-acknowledge.xml Log: https://jira.jboss.org/jira/browse/HORNETQ-116 Modified: trunk/docs/user-manual/en/pre-acknowledge.xml =================================================================== --- trunk/docs/user-manual/en/pre-acknowledge.xml 2009-09-09 13:06:55 UTC (rev 7944) +++ trunk/docs/user-manual/en/pre-acknowledge.xml 2009-09-09 13:42:27 UTC (rev 7945) @@ -1,5 +1,4 @@ <?xml version="1.0" encoding="UTF-8"?> - <!-- ============================================================================= --> <!-- Copyright © 2009 Red Hat, Inc. and others. --> <!-- --> @@ -17,7 +16,6 @@ <!-- and agrees not to assert, Section 4d of CC-BY-SA to the fullest extent --> <!-- permitted by applicable law. --> <!-- ============================================================================= --> - <chapter id="pre-acknowledge"> <title>Pre-Acknowledge Mode</title> <para>JMS specifies 3 acknowledgement modes:</para> @@ -36,6 +34,12 @@ server. However, in the case where you can afford to lose messages in event of failure, it would make sense to acknowledge the message on the server <emphasis>before</emphasis> delivering it to the client.</para> + <note> + <para>Please note, that if you use pre-acknowledge mode, then you will lose transactional + semantics for messages being consumed, since clearly they are being acknowledged first on + the server, not when you commit the transaction. This may be stating the obvious but we + like to be clear on these things to avoid confusion!</para> + </note> <para>The disadvantage of acknowledging on the server before delivery is that the message will be lost if the system crashes <emphasis>after</emphasis> acknowledging the message on the server but <emphasis>before</emphasis> it is delivered to the client. In that case, the message is @@ -62,14 +66,14 @@ // messages will be acknowledge on the server *before* being delivered to the client Session session = connection.createSession(false, HornetQSession.PRE_ACKNOWLEDGE); </programlisting> - <para>Or you can set pre-acknowledge directly on the <literal>HornetQConnectionFactory</literal> - instance using the setter method.</para> + <para>Or you can set pre-acknowledge directly on the <literal + >HornetQConnectionFactory</literal> instance using the setter method.</para> <para>To use pre-acknowledgement mode using the core API you can set it directly on the <literal>ClientSessionFactory</literal> instance using the setter method.</para> </section> <section> <title>Example</title> - <para>See <xref linkend="examples.pre-acknowledge" /> for an example which - shows how to use pre-acknowledgement mode with with JMS.</para> + <para>See <xref linkend="examples.pre-acknowledge"/> for an example which shows how to use + pre-acknowledgement mode with with JMS.</para> </section> </chapter>