1520-9202/06/$20.00 © 2006 IEEE
Published by the IEEE Computer Society
38 IT Pro July ❘ August 2006
Context-Aware
Composition of
Mobile Services
Spyros Panagiotakis and
Athanassia Alonistioti
N
ext-generation mobile networks will
need to provide flexible, customized,
context-aware, and ubiquitous multi-
media services to mobile users.
Assume, for example, a mobile user is at home
receiving real-time news video from an applica-
tion provider through a large-screen monitor.As
the mobile user leaves the house for his office,
moving from the large-screen terminal to a
portable phone, a location information server in
the service support layer notifies the application
of the location update. The application success-
fully recognizes, by scanning the user’s profile or
interacting with the user,the user’s wish to change
content (media) from video to text, and a media
converter executes the conversion.
To provide such flexible and context-aware
services, a system must be able to know at any
given time the network status, user location, pro-
files of the various entities (users, terminals, net-
work equipment, and services) involved, and
system policies. That is, it must be able to cope
with a large amount of context information.
Because developing separate application versions
for different execution contexts isn’t feasible,
applications should be largely agnostic of their
environment.We need intelligent mechanisms for
identifying the context and mapping it to appro-
priate adaptation operations on services
(Athanassia Alonistioti, Nikos Houssos, and
Spyridon Panagiotakis, “A Framework for
Reconfigurable Provisioning of Services in
Mobile Networks,” Proc. Int’l Symp. Comm.
Theory and Applications, HW Communications
Ltd., 2001, pp. 21-26).
We’ve developed an intelligent distributed
framework that enables the dynamic composition
of mobile services and applications based on exist-
ing services and technologies,while enriching them
with high-level and up-to-date contextual infor-
mation. The framework makes the service imple-
mentation totally platform-unaware, thus in-
creasing the number of potentially available serv-
ices and shortening application time-to-market.
WHAT IS CONTEXT?
Context is the combination of information rele-
vant to a user’s nearest environment, such as user
location,network,and terminal device. Contextual
information is encoded in the user profile, which
consists of user preferences, terminal, ambient, net-
work, and service profiles (3GPP, “3GPP Generic
User Profile Architecture: Stage 2,” technical spec-
ification 23.240). Because applications exchange
profiling information across different administra-
tive boundaries, to assure interoperability, it’s best
to describe these profiles using XML (http://
www.w3c.org/XML) or XML-based languages—
Web Services Description Language 1.1 (WSDL,
http://www.w3.org/TR/wsdl), Synchronized Multi-
An intelligent distributed framework
for context-aware mobile services
lets applications dynamically adapt
to changing conditions and contexts
over a large variety of
infrastructures and configurations.
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