Dr Dobb's article on WSN

[Robin Cover <robin@oasis-open.org>]

FYI:  The  April 2005 issue of Dr Dobb's carries an
article (pages 48-51) on WS-Notification.

"Exploring WS-Notification: Building a Scalable
Domotic Infrastructure"

Marco Aiello, Manuel Zanoni, Alessandro Zolet
WS-Notification is a web-service protocol that defines
a standard approach to notification.

http://www.ddj.com/articles/2005/0504/

Marco is assistant professor and head of the Distributed
Systems and Service-Oriented Computing research program at
DIT, University of Trento, Italy. He can be reached at
aiellom@ieee.org. Manuel and Alessandro are undergraduate
students in the Informatics curricula and can be reached
at jofix@inwind.it, and alessandro .zolet@virgilio.it,
respectively.

Excerpt:

Home appliances are evolving at a pace well beyond the
capabilities designers of X10 -- a standard that uses
powerlines to remotely control home devices -- ever expected.
Equipping home devices with processors and wireless connectivity
has become affordable and painless, thanks in part to wireless
connectivity Standards such as GSM, GPRS, Wi-Fi (IEEE 802.11),
Bluetooth (IEEE 802.15.1), and ZigBee (IEEE 802.15.4).

Still, one of the challenges users face is having devices
that make proper use of this communication infrastructure.
What are appropriate messaging schemes for these loosely
coupled autonomous devices? How can these devices discover
each other and interact? Interestingly, XML-based web services
offer an answer to this question.

In this article, we will examine WS- Notification, a web-
service publish/subscribe protocol that we apply to a "domotic"
living environment for elderly adults. In particular, we use
WS-Notification to integrate different sensors and actuators
in a home environment, with the goal of detecting life-
threatening situations, such as when elderly inhabitants of
the home fall.

WS-Notification is a web-service protocol that defines a
standard approach to notification via a topic-based
publish/subscribe mechanism...

We have deployed the WS-Notification server in a home with
the goal of monitoring elderly citizens and detecting if they
fall. Indeed, one of the most common accidents in the aging
population is the accidental fall that, especially if undetected,
may have dangerous effects. In Great Britain, accidental falls
constitute about 30 percent of the home accidents of people over
65. A number of sensors can be used to detect this hazardous
situation; for instance, one can place an array of infrared
sensors at the floor level, one can equip the person with an
accelerometer, or one can use fixed cameras. With the notification
server, we can actually combine more sensors to reduce the amount
of false positives. In particular, we use a custom-made
accelerometer built by ITC-irst (http://www.itc.it/irst/) and
standard fixed video cameras. State-of-the-art posture-recognition
software built by CNR-IMAG lecce (http://www.imm.cnr.it/)
analyzes the images and classifies postures into three main
categories: standing, sitting, and laying. The rule engine fuses
the data from the accelerometer and image-analysis software, and
identifies potentially dangerous situations. The information of
each sensor taken alone is not enough to detect a fall with an
acceptable reliability...

Home networking in general and domotics in particular are
applications where WS-Notification can be successfully applied.
While not all home appliances will implement a web-service
stack that goes from SOAP messages up to WSDL or even BPEL
descriptions, many will aggregate home functional units and
offer interfaces for the external world (and vice versa). Home
sensor networks will have different forms of computationally
less-expensive communication and will use web-service-ready
devices as gateways for higher level communication...

[copyright CMP]

-rcc