High Level Definition of Event-Based Applications for Pervasive Systems - Advanced Design Approaches to Emerging Software Systems - page 146

ity at the same time. It further enables to detect
different kinds of fire that also reveal different
physical properties, e.g., flaming and smoldering
fires. Thus, a proper fire fighting system should
apply temperature, smoke and carbon monoxide
detectors simultaneously.

Listing 2 displays an event specification that
can be used in fire detection scenarios. To decide
about the existence of fire, each detection method
usually determines a fixed threshold. This example
proposes to apply 100 ppm (parts per million) as
the threshold for carbon monoxide, 1.1 percent

Listing 2. Example of an event specification for fire detection scenarios.

<EVENT id=”fire” version=”1” priority=”high” lease=”6”
reliableMode=”yes”>
<SENSORDATA>
<OR>
<GREATEROREQUAL>
<VARIABLE> carbon monoxide </VARIABLE>
<CONSTANT unit=”partsPerMillion”>100</CONSTANT>
</GREATEROREQUAL>
<AND>
<GREATER>
<VARIABLE> temperature </VARIABLE>
<CONSTANT unit=”Kelvin”>353</CONSTANT>
</GREATER>
<GREATEROREQUAL>
<VARIABLE> smoke </VARIABLE>
<CONSTANT unit=”percentage”>1.1</CONSTANT>
</GREATEROREQUAL>
</AND>
</OR>
</SENSORDATA>
<CONSEQUENCE>
<TRIGGERHANDLER> sendalert </TRIGGERHANDLER>
</CONSEQUENCE>
<EXECUTION>
<TIMEINTERVAL relation=”EqualTo”>
<CONSTANT unit=”seconds”>10</CONSTANT>
</TIMEINTERVAL>
</EXECUTION>
<DIMENSION>
<BALL relation=”LessOrEqualTo”>
<CONSTANT unit=”meters”>2.5</CONSTANT>
</BALL>
</DIMENSION>
</EVENT>