High Level Definition of Event-Based Applications for Pervasive Systems - Advanced Design Approaches to Emerging Software Systems - page 171

be requested from EDTs at other nodes. Sensor
nodes are enabled to maintain several EDTs at
the same time. Using EDTs, every node in the
network can execute the complete evaluation
process without a SPoF.
EDTs address the following design criteria: Ro-
bustness , Autonomy , Transparency , Convenience
Communication-efficient means to maintain
EDTs in case of missing or failing sensing devices.
The EDTs are enabled to continue event-based
detection with a high accuracy even in case of
missing resources or failed sensing devices. For
those cases, EDTs provide efficient collabora-
tive event detection between neighboring nodes
using a lease-based publish/subscribe approach.
Appropriate on-node processing of sensed data
allows to efficiently share values of EDT nodes
by a few bytes only. The simulations clearly an-
nounced that the communication-efficiency of the
lease-based approach is very high in contrast to the
ACK-based variant. By choosing a proper leasing
time, the lease-based approach closely meets the
detection results of ACK-based collaboration but
reduces the number of collaboration messages
by a factor of at least 10. As learnt from simula-
tions, the detection performance highly depends
on the chosen leasing time as well as on the size
of the collaboration region. Both parameters are
customized in the event specification. To ease the
configuration for non-professional users, the user
assistant limits these parameters with respect to the
configuration guidelines learnt from simulations.
The lease-based publish/subscribe approach
addresses the following design criteria: Robust-
ness , Autonomy , Transparency , Energy efficiency ,
Convenience
To summarize, this chapter presented and
evaluated means that allow a user-centric design
flow for pervasive applications. Besides straight-
forward definition means, it provides a robust and
reliable concept for autonomous configuration
of event-based applications in WSNs. Criteria
for proper ease of use of application definition
were deduced from the simulation results. These

criteria support the configuration of an adequate
collaboration region and leasing time by defini-
tion of lower and upper bounds. We expect these
criteria to further ease the design of applications
based on pervasive WSNs.

REFERENCES

Aboelaze, M., & Aloul, F. (2005). Current and
future trends in sensor networks: A survey. In
Proceedings of the Second IFIP International
Conference on Wireless and Optical Communi-
cations Networks WOCN 2005 , (pp. 551-555).

Akyildiz, I. F., Su, W., Sankarasubramaniam, Y.,
& Cayirci, E. (2002). Wireless sensor networks:
A survey. Computer Networks , 38 , 393-422.
doi:10.1016/S1389-1286(01)00302-4

Brouwers, N., Corke, P., & Langendoen, K. (2008).
Darjeeling, a Java compatible virtual machine for
microcontrollers. In Companion '08: Proceed-
ings of the ACM/IFIP/USENIX Middleware '08
Conference Companion , (pp. 18-23). New York,
NY: ACM.

Buonadonna, P., Gay, D., Hellerstein, J. M., Hong,
W., & Madden, S. (2005). Task: Sensor network in
a box. In Proceedings of European Workshop on
Sensor Networks , (pp. 133-144). Istanbul, Turkey.

Cardei, M., Yang, S., & Wu, J. (2008). Algorithms
for fault-tolerant topology in heterogeneous
wireless sensor networks. IEEE Transactions on
Parallel and Distributed Systems , 19 (3).

Heinzelman, W. B., Murphy, A. L., Carvalho, H.
S., & Perillo, M. A. (2004). Middleware to support
sensor network applications. IEEE Network , 18 ,
6-14. doi:10.1109/MNET.2004.1265828

Kamiya, H., Mineno, H., Ishikawa, N., Osano, T.,
& Mizuno, T. (2008). Composite event detection
in heterogeneous sensor networks . IEEE/IPSJ
International Symposium on Applications and
the Internet, (pp. 413-416).