Technological advances in semiconductor processing and design as well as wireless networking are leading us towards the vision of Pervasive Computing. We envision that in the (near) future, devices all around a person, either embedded as a part of smart spaces, or being carried by other people in the vicinity, will provide an array of services that she might want to use. Development of customized services by integrating and executing existing ones has received a lot of attention in the last few years with respect to wired, infrastrutcure based web-services. However, service discovery and composition in web-based environments is performed in a centralized manner with the help of a fixed entity. Moreover, wired infrastructure-based service discovery and composition architectures do not take into consideration factors arising from the possible mobility of the service providers. In this paper, we present a distributed, de-centralized and fault-tolerant design architecture for reactive service composition in pervasive environments. The design of the architecture is based on a peer-to-peer model. We introduce two reactive techniques for service composition in our design. We also present the Anamika system, an initial implementation of our design architecture. We present experiments to show the functioning of our design and implementation.

Service Composition refers to creation of complex e-services with the help of smaller, simpler, easily executable lightweight e-services or components. In essence, it is much similar to component-based or object-based software design and implementation, but different in its approach. The spurt of e-services on the web has recently increased the importance of service composition. There has been some research in trying to leverage this wide array of e-services available over the network to be able to provide more customized, complex services to e-customers. In the recent past, we have also seen the increasing use of mobile devices. We have seen the deployment of ad hoc networks like Bluetooth. We envisage that in the future, service composition will play a crucial role in providing access to complex services to a mobile device by utilizing resources available in its vicinity. This paper is an attempt to summarize the existing work in the field of service composition and critically evaluate the present composition platforms. We try to judge the suitability of the current platforms to be able to do dynamic service composition in an ad hoc environment. The paper also provides an overview of our current work in this area and points to certain future directions with respect to the next generation of e-services, viz. mobile-services.

The realization of the Semantic Web is underway with the development of an arena of services providing similar properties, capabilities, interfaces, and effects. To pick one of such similar services that matches the user's requirements is a difficult task and necessitates the use of an intelligent decision making framework. This paper addresses precisely this component. We present the design of a Dynamic Web service selection framework that makes use of a semantic matcher to support matching and composition of software services. The framework also uses a recommendation system which helps a user to select the best service that matches his requirements. This recommendation system results in evolution of the framework to dynamically adapt to users requirements.

Automated composition of Web services or the process of forming new value added Web services is one of the most promising challenges in the semantic Web service research area. Semantics is one of the key elements for the automated composition of Web services because such a process requires rich machine-understandable descriptions of services that can be shared. Semantics enables Web service to describe their capabilities and processes, nevertheless there is still some work to be done. Indeed Web services described at functional level need a formal context to perform the automated composition of Web services. The suggested model (i.e., Causal link matrix) is a necessary starting point to apply problem-solving techniques such as regression-based search for Web service composition. The model supports a semantic context in order to find a correct, complete, consistent and optimal plan as a solution. In this paper an innovative and formal model for an AI planning-oriented composition is presented.

Service composition in pervasive environments enables users to utilize services in the environment to solve complex queries. Current work in development of service composition architectures focuses on wired-networked environments where solutions are centralized and tailored towards a reliable network and fixed service topology. In this paper, we present an alternate and novel design architecture of a broker-based distributed service composition protocol for pervasive environments. We present simulation results by comparing our protocol to a centralized architecture for composition. Results show that our distributed broker-based composition architecture perform better than the centralized solution in terms of composition efficiency, broker arbitration efficiency and composition radius.

Mobile information access involves retrieving information from wired service providers. Often there are situations where the information is not available from a single service provider but can be obtained by combining information from multiple service providers. It is inecient and some times impossible for a resource poor mobile device connected over a low bandwidth wireless link to coordinate such activity. In this paper, we describe a middleware to support this mode of access from resource poor mobile devices that take into consideration mobility, resource constraints and service heterogeneity.

Resulting from the constantly increasing usage of service oriented computing, the problem of automatic composition of services is rapidly gaining attention. Many solutions have been proposed, yet too little attention has been paid to thoroughly analyzing the different needs that require the ability of (automatic) service composition. This paper therefore aims at identifying the different cases in which service composition is needed and at classifying existing approaches accordingly. Three distinguishable types of service composition applications are described along with their basic problems and various approaches addressing the identified classes are presented.

As more wireless devices become available and new applications emerge for these diverse gadgets, there is an increasing need to intelligently adapt existing services (e.g., Web browsing, video streaming) to them. Adaptation is needed due to heterogeneous and vastly differing capabilities in hardware, software, and network connectivity. We argue that existing services should remain unmodified and a automatically created, adaptive, distributed service proxy architecture with properties of faulttolerance, composability is necessary for creating truly mobile services using a collection of devices. These devices form a device ensemble or a virtual device. We demonstrate feasibility of such an architecture based on our previous work in wide-area service composition [1].

Abstract—Service modeling and composition is a fundamental method for offering advanced functionality by combining a set of primitive services provided by the system. Unlike in the case of web services for which there is an abundance of reliable resources, in sensor networks, the resources are constrained and communication among nodes is error-prone and unreliable. Such a dynamic environment requires a continuous adaptation of the composition of services. In this paper, we first propose a graph-based model of sensor services that maps to the operational model of sensor networks and is amenable to analysis. Based on this model, we formulate the process of sensor service composition as a cost-optimization problem, which is NP-complete. We then propose two heuristic methods for its solution, the top-down and the bottom-up, and discuss their centralized and distributed implementations. Using simulations, we evaluate their performance.

Service Composition refers to the technique of creating complex services with the help of smaller, simpler and easily executable lightweight services or components. The spurt of e-services on the web has recently increased the importance of service composition. There has been some research in trying to leverage the wide array of e-services available over the network to be able to provide more customized, complex services to e-customers. In the recent past, we have also seen the increasing use of mobile devices. We have seen the deployment of ad hoc networks like Bluetooth. We envisage that in the future, service composition will play a crucial role in providing access to complex services to a mobile device by utilizing resources available in its vicinity.