/// <summary>
/// Contains the query logic in form of a query template.
/// </summary>
/// <param name="application">Application to host the query template.</param>
/// <returns>The new query template object.</returns>
private static QueryTemplate CreateQueryTemplate(Application application)
{
// Create stream objects as basis for query template
// specification. The specified names will be used when binding
// the query template's inputs to event producers.
CepStream <SensorReading> sensorStream = CepStream <SensorReading> .Create("sensorInput");
CepStream <LocationData> locationStream = CepStream <LocationData> .Create("locationInput");
// Extend duration of each sensor reading, so that they fall in
// a one-minute sliding window. Group by sensor ID and calculate the
// average vehicular count per group within each window.
// Include the grouping key in the aggregation result.
var avgCount = from oneMinReading in sensorStream.AlterEventDuration(e => TimeSpan.FromMinutes(1))
group oneMinReading by oneMinReading.SensorId into oneGroup
from eventWindow in oneGroup.SnapshotWindow(SnapshotWindowOutputPolicy.Clip)
select new { avgCount = eventWindow.Avg(e => e.VehicularCount), SensorId = oneGroup.Key };
// Join sensors and locations. Moreover, filter the count
// result by a threshold, which is looked up based on the
// sensor location through a user-defined function.
var joined = from averageEvent in avgCount
join locationData in locationStream
on averageEvent.SensorId equals locationData.SensorId
where averageEvent.avgCount > UserFunctions.LocationCountThreshold(locationData.LocationId)
select new
{
SensorId = locationData.SensorId,
LocationID = locationData.LocationId,
VehicularCount = averageEvent.avgCount
};
return(application.CreateQueryTemplate("SampleQueryTemplate", string.Empty, joined));
}