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Synchronous
queue consumers consume events by calling pop() on the
Nirvana queue reader object. Each pop call made on the
queue reader will synchronously retrieve the next event
from the queue.
An example of a synchronous queue reader is shown below:
public class mySyncQueueReader {
nQueueSyncReader reader = null;
nQueue myQueue = null;
public mySyncQueueReader() throws Exception
{
// construct
your session
and queue objects
here
// construct the queue
reader
nQueueReaderContext ctx = new
nQueueReaderContext(this, 10);
reader = myQueue.createReader(ctx);
}
public void start() throws Exception {
while (true) {
// pop events from
the queue
nConsumeEvent event = reader.pop();
go(event);
}
}
public void go(nConsumeEvent event) {
System.out.println("Consumed event "+event.getEventID());
}
public static void main(String[] args) {
try {
mySyncQueueReader sqr = new mySyncQueueReader();
sqr.start();
} catch (Exception e) {
e.printStackTrace();
}
}
}
Sychronous queue consumers can also be created using
a selector, which defines a set of event
properties and their values that a consumer is interested
in. For example if events are being published with the
following event properties:
nEventProperteis props =new nEventProperties();
props.put(“BONDNAME”,”bond1”);
If you then provide a message selector string in the
form of:
String selector = "BONDNAME='bond1'";
And pass this string into the constructor for the nQueueReaderContext
object shown in the example code, then your consumer
will only consume messages that contain the correct
value for the event property BONDNAME.
An example of a synchronous queue consumer can be found
here.
For more information on Nirvana message queues, please
see the API documentation.
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