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Subject svn commit: r441258 - /incubator/activemq/site/retroactive-consumer.html
Date Thu, 07 Sep 2006 22:23:11 GMT
Author: chirino
Date: Thu Sep  7 15:23:10 2006
New Revision: 441258

Latest export from confluence


Modified: incubator/activemq/site/retroactive-consumer.html
--- incubator/activemq/site/retroactive-consumer.html (original)
+++ incubator/activemq/site/retroactive-consumer.html Thu Sep  7 15:23:10 2006
@@ -277,8 +277,7 @@
             <div class="pagetitle">Retroactive Consumer</div>
-            <DIV class="wiki-content">
-<H2><A name="RetroactiveConsumer-Background"></A>Background</H2>
+            <DIV class="wiki-content"><H2><A name="RetroactiveConsumer-Background"></A>Background</H2>
 <P>A retroactive consumer is just a regular JMS consumer who indicates that at the
start of a subscription every attempt should be used to go back in time and send any old messages
(or the last message sent on that topic) that the consumer may have missed.</P>
@@ -291,7 +290,15 @@
 <DIV class="code"><DIV class="codeContent">
 <PRE class="code-java">queue = <SPAN class="code-keyword">new</SPAN> ActiveMQQueue(<SPAN
class="code-quote">&quot;TEST.QUEUE?consumer.retroactive=<SPAN class="code-keyword">true</SPAN>&quot;</SPAN>);
 consumer = session.createConsumer(queue);</PRE>
+<H2><A name="RetroactiveConsumer-Limitations"></A>Limitations</H2>
+<P>Retroactive consumer will not consistently work when used across a network of brokers.</P>
+<P>In the case of topics, when we connect broker A to broker B, broker B will send
broker A all the subscriptions that it has received. Since Broker A replicates messages to
each subscription, and we want to avoid receiving duplicates at broker B, we can&apos;t
send broker A more than 1 subscription for the same topic. To solve this So our network bridges
keep track of the subscriptions sent across and only send the first subscription to a topic.
Subsequent subscriptions increment the reference count of the subscription, but the subscription
is not actually sent.</P>
+<P>This in essence is the problem. If the first subscription to a topic is not retroactive,
it is sent B to A, and the B broker will not get the retroactive messages. Then subsequent
subscriptions could be (retroactive), but it will not cause retroactive message to sent from
broker A to broker B since the subsequent subscription will not be sent to broker A.</P></DIV>
@@ -301,8 +308,8 @@
     <DIV id="site-footer">
           Added by     <A href="">James
-    last edited by     <A href="">James
Strachan</A> on May 12, 2006
-                  &nbsp;(<A href="">view
+    last edited by     <A href="">Hiram
Chirino</A> on Sep 07, 2006
+                  &nbsp;(<A href="">view
       (<A href="">edit

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