<div class="docbook"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">10.3. Creating a group</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="Java-Broker-High-Availability-OverviewOfHA.html">Prev</a> </td><th width="60%" align="center">Chapter 10. High Availability</th><td width="20%" align="right"> <a accesskey="n" href="Java-Broker-High-Availability-Behaviour.html">Next</a></td></tr></table><hr /></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="Java-Broker-High-Availability-CreatingGroup"></a>10.3. Creating a group</h2></div></div></div><p>This section describes how to create a group. At a high level, creating a group involves
      first creating the first node standalone, then creating subsequent nodes referencing the first
      node so the nodes can introduce themselves and gradually the group is built up.</p><p>A group is created through either <a class="link" href="Java-Broker-Management-Channel-Web-Console.html" title="6.2. Web Management Console">Web Management</a>
      or the <a class="link" href="Java-Broker-Management-Channel-REST-API.html" title="6.3. REST API">REST API</a>
      or the initial configuration (<a class="xref" href="Java-Broker-Appendix-BDB-HA-initial-configuration.html" title="Appendix H. BDB HA initial configuration">Appendix H, <em>BDB HA initial configuration</em></a>
      illustrates how to use initial configuration for BDB HA group creation).
      These instructions presume you are using Web Management. To illustrate the example it builds the group
      illustrated in figure <a class="xref" href="Java-Broker-High-Availability-OverviewOfHA.html#Java-Broker-High-Availability-OverviewOfHA-Figure" title="Figure 10.1. 3-node group deployed across three Brokers.">Figure 10.1, “3-node group deployed across three Brokers.”</a></p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Install a Broker on each machine that will be used to host the group. As messaging
            clients will need to be able to connect to and authentication to all Brokers, it usually
            makes sense to choose a common authentication mechanism e.g. Simple LDAP Authentication,
            External with SSL client authentication or Kerberos.</p></li><li class="listitem"><p>Select one Broker instance to host the first node instance. This choice is an
            arbitrary one. The node is special only whilst creating group. Once creation is
            complete, all nodes will be considered equal.</p></li><li class="listitem"><p>Click the <code class="literal">Add</code> button on the Virtualhost Panel on the Broker
            tab.</p><p>
            </p><div class="orderedlist"><ol class="orderedlist" type="a"><li class="listitem"><p>Give the Virtualhost node a unique name e.g. <code class="literal">weather1</code>. The
                  name must be unique within the group and unique to that Broker. It is best if the
                  node names are chosen from a different nomenclature than the machine names
                  themselves.</p></li><li class="listitem"><p>Choose <code class="literal">BDB_HA</code> and select <code class="literal">New group</code>
                </p></li><li class="listitem"><p>Give the group a name e.g. <code class="literal">weather</code>. The group name must be
                  unique and will be the name also given to the virtualhost, so this is the name the
                  messaging clients will use in their connection url.</p></li><li class="listitem"><p>Give the address of this node. This is an address on this node's host that
                  will be used for replication purposes. The hostname <span class="emphasis"><em>must</em></span> be
                  resolvable by all the other nodes in the group. This is separate from the address
                  used by messaging clients to connect to the Broker. It is usually best to choose a
                  symbolic name, rather than an IP address.</p></li><li class="listitem"><p>Now add the node addresses of all the other nodes that will form the group. In
                  our example we are building a three node group so we give the node addresses of
                    <code class="literal">chaac:5000</code> and <code class="literal">indra:5000</code>.</p></li><li class="listitem"><p>Click Add to create the node. The virtualhost node will be created with the
                  virtualhost. As there is only one node at this stage, the role will be
                  master.</p></li></ol></div><p>
            </p><div class="figure"><a id="d0e9872"></a><p class="title"><strong>Figure 10.2. Creating 1st node in a group</strong></p><div class="figure-contents"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="100%"><tr><td><img src="images/HA-Create-1.png" height="360" alt="Creating 1st node in a group" /></td></tr></table></div></div></div><p><br class="figure-break" />
          </p></li><li class="listitem"><p>Now move to the second Broker to be the group. Click the <code class="literal">Add</code>
            button on the Virtualhost Panel on the Broker tab of the second Broker.</p><p>
            </p><div class="orderedlist"><ol class="orderedlist" type="a"><li class="listitem"><p>Give the Virtualhost node a unique name e.g.
                  <code class="literal">weather2</code>.</p></li><li class="listitem"><p>Choose <code class="literal">BDB_HA</code> and choose <code class="literal">Existing group</code>
                </p></li><li class="listitem"><p>Give the details of the <span class="emphasis"><em>existing node</em></span>. Following our
                  example, specify <code class="literal">weather</code>, <code class="literal">weather1</code> and
                    <code class="literal">thor:5000</code></p></li><li class="listitem"><p>Give the address of this node.</p></li><li class="listitem"><p>Click Add to create the node. The node will use the existing details to
                  contact it and introduce itself into the group. At this stage, the group will have
                  two nodes, with the second node in the replica role.</p></li><li class="listitem"><p>Repeat these steps until you have added all the nodes to the group.</p></li></ol></div><p>
            </p><div class="figure"><a id="d0e9930"></a><p class="title"><strong>Figure 10.3. Adding subsequent nodes to the group</strong></p><div class="figure-contents"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="100%"><tr><td><img src="images/HA-Create-2.png" height="360" alt="Adding subsequent nodes to the group" /></td></tr></table></div></div></div><p><br class="figure-break" />
          </p></li></ol></div><p>The group is now formed and is ready for us. Looking at the virtualhost node of any of the
      nodes shows a complete view of the whole group. </p><div class="figure"><a id="d0e9942"></a><p class="title"><strong>Figure 10.4. View of group from one node</strong></p><div class="figure-contents"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="100%"><tr><td><img src="images/HA-Create-3.png" height="360" alt="View of group from one node" /></td></tr></table></div></div></div><p><br class="figure-break" /></p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="Java-Broker-High-Availability-OverviewOfHA.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="Java-Broker-High-Availability.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="Java-Broker-High-Availability-Behaviour.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">10.2. High Availability Overview </td><td width="20%" align="center"><a accesskey="h" href="Apache-Qpid-Broker-J-Book.html">Home</a></td><td width="40%" align="right" valign="top"> 10.4. Behaviour of the Group</td></tr></table></div></div>