QPID-4498: HA module should only initialize if requested

This commit provides better control over loading the HA module. In particular it
is not loaded if no ha options are set. This will prevent clashes with the old
cluster plugin in configurations where the HA module is not explicitly used.
HA documentation has been updated to state that HA and old cluster cannot be used
together.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk/qpid@1419850 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 40 insertions, 1 deletions

diff --git a/doc/book/src/cpp-broker/Active-Passive-Cluster.xml b/doc/book/src/cpp-broker/Active-Passive-Cluster.xml
index 65ce108aef..be5cb14a61 100644
--- a/doc/book/src/cpp-broker/Active-Passive-Cluster.xml
+++ b/doc/book/src/cpp-broker/Active-Passive-Cluster.xml
@@ -173,6 +173,13 @@ under the License.
 	  </listitem>
 	</itemizedlist>
       </para>
+      <para>
+	You should not enable the old and new cluster modules at the same time
+	in a broker, as they may interfere with each other. In other words you
+	should not set <literal>cluster-name</literal> at the same time as
+	either <literal>ha-cluster</literal> or
+	<literal>ha-queue-replication</literal>
+      </para>
     </section>
     <section>
       <title>Limitations</title>
@@ -254,6 +261,14 @@ under the License.
 	  </row>
 	  <row>
 	    <entry>
+	      <literal>ha-queue-replication <replaceable>yes|no</replaceable></literal>
+	    </entry>
+	    <entry>
+	      Enable replication of specific queues without joining a cluster, see <xref linkend="ha-queue-replication"/>.
+	    </entry>
+	  </row>
+	  <row>
+	    <entry>
 	      <literal>ha-brokers-url <replaceable>URL</replaceable></literal>
 	    </entry>
 	    <entry>
@@ -548,7 +563,7 @@ NOTE: fencing is not shown, you must configure fencing appropriately for your cl
   </section>
 
   <section id="ha-creating-replicated">
-    <title>Creating replicated queues and exchanges</title>
+    <title>Controlling replication of queues and exchanges</title>
     <para>
       By default, queues and exchanges are not replicated automatically. You can change
       the default behavior by setting the <literal>ha-replicate</literal> configuration
@@ -849,6 +864,30 @@ NOTE: fencing is not shown, you must configure fencing appropriately for your cl
       or to simulate a cluster on a single node. For deployment, a resource manager is required.
     </para>
   </section>
+  <section id="ha-queue-replication">
+    <title>Replicating specific queues</title>
+    <para>
+      In addition to the automatic replication performed in a cluster, you can
+      set up replication for specific queues between arbitrary brokers, even if
+      the brokers are not members of a cluster. The command:
+    </para>
+    <programlisting>
+      qpid-ha replicate <replaceable>QUEUE</replaceable> <replaceable>REMOTE-BROKER</replaceable>
+    </programlisting>
+    <para>
+    sets up replication of <replaceable>QUEUE</replaceable> on <replaceable>REMOTE-BROKER</replaceable> to <replaceable>QUEUE</replaceable> on the current broker.
+    </para>
+    <para>
+      Set the configuration option
+      <literal>ha-queue-replication=yes</literal> on both brokers to enable this
+      feature on non-cluster brokers. It is automatically enabled for brokers
+      that are part of a cluster.
+    </para>
+    <para>
+      Note that this feature does not provide automatic fail-over, for that you
+      need to run a cluster.
+    </para>
+  </section>
 </section>
 
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