There has been a tremendous rise in the use of Wireless Application Protocol (WAP) services for cellular telephones. Such services include electronic mail, printing, fax delivery, and weather reports. But, current services are limited both in type and nature. Today, mobile telephone users need access to more dynamic, location-based, distributed services that include both hardware resources, like printers and computers, and software services, like application software. Problems due to mobility include clients disconnecting from the network, services leaving the network, and communication problems. This research proposes and demonstrates the feasibility of a framework for a system to meet such a need. More specifically, this work develops and demonstrates a distributed environment where mobile telephone users have access to services dynamically as they enter and leave different service areas. It also provides a framework to support mobility in the application layer context. This work utilizes Sun Microsystem's JINI connection technology to provide distributed services to mobile telephones over WAP. It provides a prototype system to provide Java based software services to mobile telephones. The work also provides several optimizations with respect to client communication by harnessing key features of WAP. This provides a robust, dynamic environment for service provisioning. / Master of Science

Most of the service discovery protocols available on the Internet are built upon its logical structure. This phenomenon can be observed frequently from the way in which they behave. For instance, Jini and SLP service providers announce their presence by multicasting service advertisements, an approach that is neither intended to scale nor capable of scaling to the size of the Internet. With mobile and wireless devices becoming increasingly popular, there appears to be a need for performing service discovery in a wide-area context, as there is very little direct correlation between the Internet topology and geographic locations. Even for desktop computers, such a need can arise from time to time. This problem suggests the necessity for an architecture that allows users to locate resources on the Internet using geographic criteria. This thesis presents an architecture that can be deployed with minimal effort in the existing network infrastructure. The geographic information can be shared among multiple applications in a fashion similar to the way DNS is shared throughout the Internet. The design and implementation of the architecture are discussed in detail, and three case studies are used to illustrate how the architecture can be employed by various applications to satisfy dramatically different needs of end-users.

The widespread deployment of inexpensive communications technology, computational resources in the networking infrastructure and network-enabled end devices pose a problem for end users: how to locate a particular network service or device out of those accessible. Service providers use Service Discovery Services (SDS) to advertise the descriptions of available or already running services, while clients use SDS to compose queries for locating these services. Service descriptions and queries use the eXtensible Markup Language (XML) to encode vendor specific information and device- or service-specific capabilities as well as the actions addressed to the device or service. This report presents the architecture and implementation of a SDS used to locate enabled LCD projectors and use them for presentation. The presentation service provides all the capabilities to the end user so that he can choose the projector device of his interest and use the graphical user interface to navigate thorough the presentation. The presentation service also has the capability to use more than one projector at a time. We use the Universal Plug and Play suite of protocols to establish the communication between client and the projector device.

Most of the service discovery protocols available on the Internet are built upon its logical structure. This phenomenon can be observed frequently from the way in which they behave. For instance, Jini and SLP service providers announce their presence by multicasting service advertisements, an approach that is neither intended to scale nor capable of scaling to the size of the Internet. With mobile and wireless devices becoming increasingly popular, there appears to be a need for performing service discovery in a wide-area context, as there is very little direct correlation between the Internet topology and geographic locations. Even for desktop computers, such a need can arise from time to time. This problem suggests the necessity for an architecture that allows users to locate resources on the Internet using geographic criteria. This thesis presents an architecture that can be deployed with minimal effort in the existing network infrastructure. The geographic information can be shared among multiple applications in a fashion similar to the way DNS is shared throughout the Internet. The design and implementation of the architecture are discussed in detail, and three case studies are used to illustrate how the architecture can be employed by various applications to satisfy dramatically different needs of end-users.

The World Wide Web is transitioning from being a mere collection of documents that contain useful information toward providing a collection of services that perform useful tasks. The emerging Web service technology has been envisioned as the next technological wave and is expected to play an important role in this recent transformation of the Web. By providing interoperable interface standards for application-to-application communication, Web services can be combined with component-based software development to promote application interaction and integration within and across enterprises. To make Web services for service-oriented computing operational, it is important that Web services repositories not only be well-structured but also provide efficient tools for an environment supporting reusable software components for both service providers and consumers. As the potential of Web services for service-oriented computing is becoming widely recognized, the demand for an integrated framework that facilitates service discovery and publishing is concomitantly growing.In our research, we propose a framework that facilitates Web service discovery and publishing by combining clustering techniques and leveraging the semantics of the XML-based service specification in WSDL files. We believe that this is one of the first attempts at applying unsupervised artificial neural network-based machine-learning techniques in the Web service domain. Our proposed approach has several appealing features: (1) It minimizes the requirements of prior knowledge from both service providers and consumers, (2) It avoids exploiting domain-dependent ontologies,(3) It is able to visualize the information space of Web services by providing a category map that depicts the semantic relationships among them,(4) It is able to semi-automatically generate Web service taxonomies that reflect both capability and geographic context, and(5) It allows service consumers to combine multiple search strategies in a flexible manner.We have developed a Web service discovery tool based on the proposed approach using an unsupervised artificial neural network and empirically evaluated the proposed approach and tool using real Web service descriptions drawn from operational Web services repositories. We believe that both service providers and consumers in a service-oriented computing environment can benefit from our Web service discovery approach.

With the advent of portable devices (e.g., smartphones) and the advances in wireless networking technologies (e.g., WLAN, GPRS, UMTS), the vision of ubiquitous computing is becoming a reality. It aims to facilitate user tasks through the seamless utilization of heterogeneous computing and communication capabilities (represented as services) available in the environment. Service discovery, which is necessary for achieving the above goal, must be aware of the service's non-functional properties due to the challenges posed by ubiquitous computing, such as device portability and mobility. This thesis proposes an overall solution that supports QoS-aware service discovery in ubiquitous computing environments. Our contribution lies in substantiating QoS awareness in the following three aspects. Firstly, during the process of discovering services, the expiring wireless links resulting from device mobility are identified and avoided since they cause service failures and thus hamper service reliability. Secondly, as mu tiple services can be discovered, a comprehensive utility function is proposed to evaluate services in terms of their various non-functional properties, meanwhile taking into account the service user's preferences among them, for the purpose of selecting the best one. Thirdly, to avoid untrustworthy services, a distributed reputation mechanism is proposed to facilitate the evaluation of the service host's trustworthiness. The above three proposed solutions are extensively evaluated respectively, based on analysis and simulation. They are further incorporated into a middleware that supports QoS aware Web service discovery in ubiquitous computing environments. A prototype implementing the middleware is deployed and evaluated. The results show that the overhead introduced by QoS awareness seems reasonable.

The most dominant architecture in the contemporary business domain is Service Oriented Architecture (SOA). The large number of the existing service description and discovery systems available today, including the ones proposed in research proposals, reveals an increasing need for adaptive, semantically enriched and context-aware, wide-area service discovery. This need will become more intense in the years to come as the number of available services increases rapidly. The main reason behind the existence of a plethora of such systems is that before these initiatives, the standard in service discovery was taking into account only the syntactic descriptions of the services, causing conflicts when services, with similar syntactic descriptions, needed to be evaluated. The research solutions available today offer efficient and accurate discovery at the syntactic, functional semantic and non-functional semantic level. However, the problem is that there is no general consensus yet regarding service discovery. Research by its very nature, leads to point solutions rather than complete systems. Based on these observations, we propose an adaptive service description and discovery framework for carrier applications, enabling the model-driven specification of services and client profiles, and also, for allowing the dynamic configuration of the services to meet specific quality requirements defined by the clients. The framework was implemented in the context of Model Driven Development, to ensure platform independence at the level of the specification of services. The framework takes the union of the point solutions offered by research proposals in the area of service description and discovery, creates an abstract model, and can compile that model to platform specific code. More specifically, services for carrier applications can be specified in a platform independent way both in terms of service signatures (syntactic properties) and in terms of the functionality and the QoS service characteristics (semantic properties). A model transformation framework allows for the creation of a platform specific model for the description of services in a specific technology platform (e.g., Web services). The framework is extensible to accommodate future extensions. In addition, as a proof of concept, we designed and developed an Eclipse Rich Client Platform (RCP) prototype tool, implementing our proposal.

Recent technological advancements are enabling the vision of pervasive or ubiquitous computing to become a reality. Service discovery is vital in such a computing paradigm, where a great number of devices and software components collaborate unobtrusively and provide numerous services. Current service-discovery protocols do not make use of contextual information in discovering services, and as a result, fail to provide the most appropriate and relevant services for users. In addition, current protocols rely on keyword-based search techniques and do not consider the semantic description of services. Thus, they suffer from poor precision and recall. To address the need for a discovery architecture that supports the envisioned scenarios of pervasive computing, we propose a context-aware service-discovery protocol that exploits meaningful contextual information, either static or dynamic, to provide users with the most suitable and relevant services. The architecture relies on a shared, ontology-based, semantic representation of services and context to enhance precision and recall, and to enable knowledge sharing, capability-based search, autonomous reasoning, and semantic matchmaking. Furthermore, the architecture facilitates a dynamic service-selection mechanism to filter and rank matching services, based on their dynamic contextual attributes, which further enhances the discovery process and saves users time and effort. Our empirical results indicate the effectiveness and feasibility of the proposed architecture.

The most dominant architecture in the contemporary business domain is Service Oriented Architecture (SOA). The large number of the existing service description and discovery systems available today, including the ones proposed in research proposals, reveals an increasing need for adaptive, semantically enriched and context-aware, wide-area service discovery. This need will become more intense in the years to come as the number of available services increases rapidly. The main reason behind the existence of a plethora of such systems is that before these initiatives, the standard in service discovery was taking into account only the syntactic descriptions of the services, causing conflicts when services, with similar syntactic descriptions, needed to be evaluated. The research solutions available today offer efficient and accurate discovery at the syntactic, functional semantic and non-functional semantic level. However, the problem is that there is no general consensus yet regarding service discovery. Research by its very nature, leads to point solutions rather than complete systems. Based on these observations, we propose an adaptive service description and discovery framework for carrier applications, enabling the model-driven specification of services and client profiles, and also, for allowing the dynamic configuration of the services to meet specific quality requirements defined by the clients. The framework was implemented in the context of Model Driven Development, to ensure platform independence at the level of the specification of services. The framework takes the union of the point solutions offered by research proposals in the area of service description and discovery, creates an abstract model, and can compile that model to platform specific code. More specifically, services for carrier applications can be specified in a platform independent way both in terms of service signatures (syntactic properties) and in terms of the functionality and the QoS service characteristics (semantic properties). A model transformation framework allows for the creation of a platform specific model for the description of services in a specific technology platform (e.g., Web services). The framework is extensible to accommodate future extensions. In addition, as a proof of concept, we designed and developed an Eclipse Rich Client Platform (RCP) prototype tool, implementing our proposal.

Recent technological advancements are enabling the vision of pervasive or ubiquitous computing to become a reality. Service discovery is vital in such a computing paradigm, where a great number of devices and software components collaborate unobtrusively and provide numerous services. Current service-discovery protocols do not make use of contextual information in discovering services, and as a result, fail to provide the most appropriate and relevant services for users. In addition, current protocols rely on keyword-based search techniques and do not consider the semantic description of services. Thus, they suffer from poor precision and recall. To address the need for a discovery architecture that supports the envisioned scenarios of pervasive computing, we propose a context-aware service-discovery protocol that exploits meaningful contextual information, either static or dynamic, to provide users with the most suitable and relevant services. The architecture relies on a shared, ontology-based, semantic representation of services and context to enhance precision and recall, and to enable knowledge sharing, capability-based search, autonomous reasoning, and semantic matchmaking. Furthermore, the architecture facilitates a dynamic service-selection mechanism to filter and rank matching services, based on their dynamic contextual attributes, which further enhances the discovery process and saves users time and effort. Our empirical results indicate the effectiveness and feasibility of the proposed architecture.