Electronic documents are becoming increasingly rich in content and varied in format
and structure. At the same time, user preferences vary towards the contents and their
devices are getting increasingly varied in capabilities. This mismatch between rich
contents and user preferences along with the end device capability presents a challenge
in providing ubiquitous access to these contents. Content adaptation is primarily used to
bridge the mismatch by providing users with contents that is tailored to the given
contexts e.g., device capability, preferences, or network bandwidth. Existing content
adaptation systems employing these approaches such as client-side, server-side or
proxy-side adaptation, operate in isolation, often encounter limited adaptation
functionality, get overload if too many concurrent users and open to single point of
failure, thus limiting the scope and scale of their services. To move beyond these
shortcomings, this thesis establishes the basis for developing content adaptation
solutions that are efficient and scalable. It presents a framework to enable content
adaptation to be consumed as Web services provided by third-party service providers,
which is termed as “service-oriented content adaptation”. Towards this perspective, this
thesis addresses five key issues – how to enable content adaptation as services (serviceoriented
framework);
how
to
locate
services
in
the
network
(service
discovery
protocol);
how
to select best possible services (path determination); how to provide quality
assurance (service level agreement (SLA) framework); and how to negotiate quality of
service (QoS negotiation). Specifically, we have: (i) identified the key research
challenges for service-oriented content adaptation, along with a systematic
understanding of the content adaptation research spectrum, captured in a taxonomy of
content adaptation systems; (ii) developed an architectural framework that provides the
basis for enabling content adaptation as Web services, providing the facilities to serve
clients’ content adaptation requests through the client-side brokering; (iii) developed a
service discovery protocol, by taking into account the searching space, searching time,
match type of the services and physical location of the service providers; (iv) developed
a mechanism to choose the best possible combination of services to serve a given
content adaptation request, considering QoS levels offered; (v) developed an
architectural framework that provides the basis for managing quality through the
conceptualization of service level agreement; and (vi) introduced a strategy for QoS
negotiation between multiple brokers and service providers, by taking into account the
incoming requests and server utilization and, thus requiring the basis of determining
serving priority and negotiating new QoS levels. The performance of the proposed
solutions are compared with other competitive solutions and shown to be substantially
better