Sun Java System Message Queue 4.2 Developer's Guide for Java Clients

A Destination Metrics Example

The source file for this code example is DestMetrics.java. This client application monitors a specific destination on a broker. It accepts the destination type and name as parameters, and it constructs a metrics topic name of the form mq.metrics.destination.queue.monitored_destination_name or mq.metrics.destination.topic.monitored_destination_name .

Example 4–6 shows how to subscribe to the metrics topic for monitoring a specified destination.


Example 4–6 Example of Subscribing to a Destination Metrics Topic

com.sun.messaging.TopicConnectionFactory metricConnectionFactory;
TopicConnection             metricConnection;
TopicSession                metricSession;
TopicSubscriber             metricSubscriber;
Topic                       metricTopic;
String                      metricTopicName = null;
String                      destName = null,
                            destType = null;

for (int i = 0; i < args.length; ++i)  {
    ...
    } else if (args[i].equals("-n"))  {
            destName = args[i+1];
    } else if (args[i].equals("-t"))  {
            destType = args[i+1];
    }
}

metricConnectionFactory = new com.sun.messaging.TopicConnectionFactory();

metricConnection = metricConnectionFactory.createTopicConnection();
metricConnection.start();

metricSession = metricConnection.createTopicSession(false,
                   Session.AUTO_ACKNOWLEDGE);

if (destType.equals("q"))  {
    metricTopicName = "mq.metrics.destination.queue." + destName;
} else  {
    metricTopicName = "mq.metrics.destination.topic." + destName;
}

metricTopic = metricSession.createTopic(metricTopicName);

metricSubscriber = metricSession.createSubscriber(metricTopic);
metricSubscriber.setMessageListener(this);

The incoming message is processed in the onMessage() method, as shown in Example 4–7:


Example 4–7 Example of Processing a Destination Metrics Message

public void onMessage(Message m)  {
   try {
        MapMessage mapMsg = (MapMessage)m;
        String type = mapMsg.getStringProperty("type");

        if (type.equals(metricTopicName))  {
            String oneRow[] = new String[ 11 ];
            int i = 0;

            /*
            * Extract destination metrics
            */
            oneRow[i++] = Long.toString(mapMsg.getLong("numMsgsIn"));
            oneRow[i++] = Long.toString(mapMsg.getLong("numMsgsOut"));
            oneRow[i++] = Long.toString(mapMsg.getLong("msgBytesIn"));
            oneRow[i++] = Long.toString(mapMsg.getLong("msgBytesOut"));

            oneRow[i++] = Long.toString(mapMsg.getLong("numMsgs"));
            oneRow[i++] = Long.toString(mapMsg.getLong("peakNumMsgs"));
            oneRow[i++] = Long.toString(mapMsg.getLong("avgNumMsgs"));

            oneRow[i++] = Long.toString(mapMsg.getLong("totalMsgBytes")/1024);
            oneRow[i++] = Long.toString
                                   (mapMsg.getLong("peakTotalMsgBytes")/1024);
            oneRow[i++] = Long.toString
                                   (mapMsg.getLong("avgTotalMsgBytes")/1024);

            oneRow[i++] = Long.toString(mapMsg.getLong("peakMsgBytes")/1024);

            mp.add(oneRow);
            ...
            }
    } catch (Exception e)  {
            System.err.println("onMessage: Exception caught: " + e);
    }
}               

Notice how the metrics type is extracted, using the getStringProperty() method as in the previous examples, and is checked. Also notice how various destination data are extracted, using the getLong() method of mapMsg.

You can run this example monitoring client with one of the following commands:

java DestMetrics -t t -n topic_name
java DestMetrics -t q -n queue_name

Using a queue named SimpleQueue as an example, the command would be:

java DestMetrics -t q -n SimpleQueue

The output looks like the following:


------------------------------------------------------------------------------
Msgs       Msg   Bytes  Msg Count        Tot Msg Bytes(k)    Largest Msg
In   Out   In    Out    Curr  Peak  Avg  Curr  Peak  Avg     (k)
------------------------------------------------------------------------------
500   0   318000  0     500   500   250  310   310   155      0