09-10-2012, 01:37 PM
Hermes: a Context-Aware Application Development Framework for the Mobile Environment
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INTRODUCTION
This paper describes a next generation software toolkit which
provides a framework, including security and intelligibility
support, for developing more powerful context-aware applications
for the modern mobile environment.
Modern mobile computing environments, with reasonable
connectivity, processing power and sensing capabilities on
portable devices provide a means of achieving truly ubiquitous
context-aware computing. To application developers, the mobile
environment also presents a new and unique set of challenges:
1) Limited resources: Restrictions on communication, data
storage, power, etc. that vary for each device in the ecosystem.
2) Large number of information sources: Fusing, filtering and
regulating the flow of context information from various
sources (sensors, online information sources, etc) bring further
overheads to the context-aware application developer’s task.
3) Increased security risk: Components/information sources of
applications are spread out on physically separated devices,
some of which may not be secure.
4) Usability issues: Context-aware applications are becoming
extremely complex where the reasons and logic behind
proactive application actions may not be intelligible to users
causing users to mistrust applications and hinder adoption.
5) Component and information reuse: Context-aware
applications should leverage the information derived by other
applications which requires a uniform method of describing
context information to allow dynamic application integration.
ARCHITECTURE
The Hermes framework is designed around a concept of using
context widgets as the basic building block. We define the
widgets as light-weight program modules that are responsible for
a single type of context information (e.g. location, activity)
belonging to a single entity (any place, person or object). Widgets
can exist on devices or in the cloud or on the telecommunication
infrastructure. To reduce the overall weight of the widgets,
functionality common across all widgets on a device are extracted
into a common lower layer (Figure 1), i.e., the Shared Hermes
Service Infrastructure (SHSI). A common SHSI layer also reduces
communication costs and possibly provides efficient storage.
Widgets connect to other widgets forming an ad-hoc widget
network, which in most scenarios would have a tree like topology
(Figure 1).
PROGRESS & FUTURE WORK
We have completed the design for the overall architecture,
implemented prototype widgets and SHSI layers, and developed
the security protocols. In parallel, we use the toolkit to build a
variety of mobile context-aware applications. The field experience
allows us to further refine the toolkit APIs.
We plan to investigate the possibility of designing a uniform and
extendable model for representing context allowing widgets
developed by various parties to connect and exchange context
information without manual intervention or prior knowledge of
other widgets. Development has just begun on intelligibility
support, involving methods to allow developers to describe a
widget’s internal logic and techniques to concatenate explanations
from various widgets.