Listening for events with particular content
The sample monitor is very simple. It just logs all
StockTick events. The content of the
StockTick event is not relevant when matching. See
Example
of a simple monitor. However, you can filter events according to their content. To alter the example so that the monitor logs only
StockTick events for a given stock, you must specify a filter on the first field in the event template. For example, suppose you want to log only
ACME stock ticks. You need to change the following line:
on all StockTick(*,*):newTick processTick();
to this:
on all StockTick("ACME",*):newTick processTick();
Now the event listener triggers on only StockTick events whose name field matches ACME.
To filter StockTick events based on their price, you might specify the event template shown below. This event template specifies that you are interested in all StockTick events whose price is 50.5 or greater.
on all StockTick(*, >=50.5):newTick processTick();