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<appendix id="Java-Broker-Appendix-Queue-Alerts">
  <title>Queue Alerts</title>
  <para>The Broker supports a variety of queue alerting thresholds. Once configured on a queue,
    these limits will be periodically written to the log if these limits are breached, until the
    condition is rectified.</para>
  <para>For example, if queue <literal>myqueue</literal> is configured with a message count alert of
    1000, and then owing to a failure of a downstream system messages begin to accumulate on the
    queue, the following alerts will be written periodically to the log. </para>
  <screen>
INFO [default:VirtualHostHouseKeepingTask] (queue.NotificationCheck) - MESSAGE_COUNT_ALERT
           On Queue myqueue - 1272: Maximum count on queue threshold (1000) breached.
  </screen>
  <para>Note that queue alerts are <emphasis>soft</emphasis> in nature; breaching the limit will
    merely cause the alerts to be generated but messages will still be accepted to the queue.</para>
  <table pgwide="1" id="Java-Broker-Appendix-Queue-Alerts-Alerting-Messages">
    <title>Queue Alerts</title>
    <tgroup cols="2">
      <thead>
        <row>
          <entry>Alert Name</entry>
          <entry>Alert Format and Purpose</entry>
        </row>
      </thead>
      <tbody>
        <row>
          <entry morerows="1">MESSAGE_COUNT_ALERT</entry>
          <entry> MESSAGE_COUNT_ALERT On Queue <replaceable>queuename</replaceable> -
              <replaceable>number of messages</replaceable>: Maximum count on queue threshold
              (<replaceable>limit</replaceable>) breached. </entry>
        </row>
        <row>
          <entry>
            <para>The number of messages on the given queue has breached its configured
              limit.</para>
          </entry>
        </row>
        <row>
          <entry morerows="1">MESSAGE_SIZE_ALERT</entry>
          <entry> MESSAGE_SIZE_ALERT On Queue <replaceable>queuename</replaceable>
              -<replaceable>message size</replaceable> : Maximum message size threshold
              (<replaceable>limit</replaceable>) breached. [Message ID=<replaceable>message
              id</replaceable>]</entry>
        </row>
        <row>
          <entry>
            <para>The size of an individual messages has breached its configured limit.</para>
          </entry>
        </row>
        <row>
          <entry morerows="1">QUEUE_DEPTH_ALERT</entry>
          <entry> QUEUE_DEPTH_ALERT On Queue <replaceable>queuename</replaceable> -
              <replaceable>total size of all messages on queue</replaceable> : Maximum queue depth
            threshold (<replaceable>limit</replaceable>) breached.</entry>
        </row>
        <row>
          <entry>
            <para>The total size of all messages on the queue has breached its configured
              limit.</para>
          </entry>
        </row>
        <row>
          <entry morerows="1">MESSAGE_AGE_ALERT</entry>
          <entry>MESSAGE_AGE_ALERT On Queue <replaceable>queuename</replaceable> - <replaceable>age
              of message</replaceable> : Maximum age on queue threshold
              (<replaceable>limit</replaceable>) breached. </entry>
        </row>
        <row>
          <entry>
            <para>The age of a message on the given queue has breached its configured limit.</para>
          </entry>
        </row>
      </tbody>
    </tgroup>
  </table>
</appendix>
