Dynamic context bindings : infrastructural support for context-aware applications


Broens, Tom Henri Ferdinand (2008) Dynamic context bindings : infrastructural support for context-aware applications. thesis.

Abstract:The world is increasingly equipped with high-capacity, interconnected,
mobile and embedded computing devices. Context-awareness provides an
attractive approach to personalize applications such that they better suit the
user’s needs in this rich computing environment.
Context-aware applications use context information, offered by context
sources, to adapt their behavior to the situation at hand. The exchange of
context information requires an association between a context consuming
context-aware application and suitable context producing context sources.
We call these associations ‘context bindings’.
Developing context-aware applications is complex due to some intrinsic
characteristics of context sources. Firstly, context sources are distributed.
Consequently, creating a context binding requires some form of discovery
and selection of context sources. Secondly, context sources are arbitrary
available during the life-span of the application. This makes a binding hard
to maintain. Finally, context sources offer context information with a
fluctuating quality. This makes a binding possibly unsuitable for the
application. Currently, developers need to spend considerable effort to
develop application code to create and maintain required context bindings,
which can deal with these complexities.
This thesis provides insights in the generic characteristics of contextaware
applications and their development process. We propose an
abstraction, called the Context Binding Transparency. This transparency has
as goal to mask the complexities of creating and maintaining context
bindings for the application developer. In this way, we facilitate the
development process of context-aware applications. The responsibility for
creating and maintaining context bindings is relieved from the application
developer and is shifted to a context binding infrastructure. This enables
application developers to focus on the development of primary application
logic rather than the logic needed to create and maintain context bindings. The application developer interacts with the context binding
infrastructure using context retrieval and publishing services, and a context
requirement specification language. This language enables application
developers to specify their requirement at a high level of abstraction rather
than in programming code. In this thesis, we propose a realization of such a
context requirement specification language, coined the Context Binding
Description Language (CBDL). This language is developed to be generic for
a broad range of context-aware applications.
Additionally, we propose a realization of a context binding infrastructure
called the Context-Aware Component Infrastructure (CACI). This
infrastructure realizes a context binding transparency and is composed of a
context binding mechanism and a context discovery interoperability
The context binding mechanism uses CBDL documents, specified by
the application developers, to create and maintain context bindings on
behalf of the application. The process of creating a binding consists of
discovery of context sources at available context discovery mechanisms,
selection of suitable context sources, establishment of a binding of the
application to these context sources, and maintenance of this binding.
Maintenance of a context binding includes re-binding to other suitable
context sources in case of lost or (re-)appearing context sources and
fluctuating quality of context. This thesis gives an example of a possible rebinding
The context discovery interoperability mechanism enables contextaware
applications to interoperate transparently with different context
discovery mechanisms available in the application environment. The goal of
the interoperability mechanism is to hide the heterogeneity and fluctuating
availability of context discovery mechanisms for context-aware applications.
The context discovery interoperability mechanism is a supporting
mechanism for the context binding mechanism. It can also be used
independently by context-aware applications that do not leverage from the
context binding mechanism.
We have created a proof-of-concept prototype of CACI, using the OSGi
component framework. The prototype includes implementations of the
context binding mechanism and the context discovery interoperability
Evaluation of the proposed context binding transparency and
infrastructure consists of a user survey and a comparison on the
development effort and software quality of a Telemedicine case
implementation with and without CACI. The survey indicated a general
interest of possible users in the features of the context binding
transparency. The case implementations indicated a possible improvement in the development process of higher quality context-aware applications
when using a context binding infrastructure.
This research stresses that the availability of context information and the
quality of this information highly influences the development of contextaware
applications. By using a middleware infrastructure to support the
creation and maintenance of context bindings, the development of higher
quality context-aware applications can be simplified.
Item Type:Thesis
Research Chair:
Research Group:
Link to this item:http://purl.utwente.nl/publications/60131
Official URL:http://dx.doi.org/10.3990/1.9789075176476
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