Towards a Solution for the Public Web-Based GIS Monitoring and Alerting System - Geoinformatics for Intelligent Transportation - page 130

stabilization of API and testing with SES speci cation, it will be integrated directly

into WEDA API. In the scope of this paper we will only highlight some of the
components that build together the practical implementation of SOA 2.0 architecture.

For example the Noti cation manager component reacts on rule actions from the

CEP server and parses the list of subscriber

￿

s topics to make the correct push of
an event to appropriate event sink. Events are de

'

ned by the end application. An

example of event-type (SASAlert) follows:

—

￿ Event generator integration point EventReceiver metadata service is the main

integration point for monitoring systems, network sensors and other event
generators (event sources) which send an event into the CEP server for further
processing.

Statement manager metadata service is an integration point for any adminis-
tration tool that allows de

￿

nition of topics. Thanks to the StatementManager
service, experts can provide a set of rules that may change over time, due to the
dynamic nature of the domain. Client application behaviour can be changed
only by changing the set of rules, nothing has to be programmed. An example
rule provided as EPL statement follows. This example statement

res as soon as

a LocationSensor of a certain device does not fire events for 10 s. Every user can

then subscribe for this topic.

SELECT count(*), Identi er FROM LocationSensor.win:
time(10 s)
GROUP BY LocationSensor.Identi er HAVING count(*) = 0

6 Conclusions

In this work, the author presents the application (experimental system) of the
WEDA architectural style for developing solutions. The paper

also shows performance results measured on the system. It shows that RT is stable

“ GIS on the web ”