<div class="wiki-content maincontent"><p>Discovery refers to either a client (producer or consumer) establishing a 'transport connector' to the broker or a broker establishing 'network connector' to another broker without explicit static configuration of broker (IP or hostname).</p>

<p>The scheme 'multicast' refers to either listening for or advertising discovery events on a multicast address. zeroconf is similar to multicast, except for protocol specific to Apple's Rendezvous (bonjour).</p>

<h3 id="Whatisthedifferencebetweendiscovery,multicastandzeroconf-Broker">Broker</h3>

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   &lt;networkConnectors&gt;
     &lt;networkConnector name="default" uri="multicast://default"/&gt;
   &lt;/networkConnectors&gt;
</pre>
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<p>The above configuration in the broker xml file will make it automatically establish network connectors to other brokers that advertise themselves on the multicast address: when this broker gets a discovery event from another broker, the event has information that enables it to establish network connector to that broker.</p>

<p>Self-advertisement is facilitated by the following config:</p>


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  &lt;transportConnectors&gt;
      &lt;transportConnector name="default" uri="tcp://localhost:61616" discoveryUri="multicast://default"/&gt;
   &lt;/transportConnectors&gt;
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<h3 id="Whatisthedifferencebetweendiscovery,multicastandzeroconf-Client">Client</h3>

<p>An example usage of discovery on the client side (using the transport 'discovery' that uses discovery agent) ...</p>


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 &lt;transportConnectors&gt;
      &lt;transportConnector name="default" uri="discovery:(multicast://default)"/&gt;
   &lt;/transportConnectors&gt;
</pre>
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<p>ps: discovery (which is a confusing name) is just like a 'reliable' transport such as <a shape="rect" href="failover-transport-reference.html">failover</a>. If it is unable to connect to a broker, it will try another broker (assuming it<br clear="none">
heard its advertisement over multicast).</p></div>