Service discovery is a critical functionality of emerging pervasive computing environments. In such environments, service discovery mechanisms need to (i) overcome the heterogeneity of hardware devices, software platforms, and networking infrastructures; and (ii) provide users with an accurate selection of services that meet their current requirements. To address these issues, we have developed the Multi-Protocol Service Discovery and Access (MSDA) middleware platform 2, which provides context-aware service discovery and access in pervasive environments. This paper primarily focuses on the design and implementation of the context-awareness support of MSDA. Context-awareness not only provides a more accurate service selection, but also enables a more efficient dissemination of service requests across heterogeneous pervasive environments. We present the design and prototype implementation of MSDA, along with experimental results that demonstrate the advantages derived by introducing context awareness. 1.

Abstract — In ad-hoc networks, mobile devices communicate via wireless links without the aid of any fixed networking infrastructure. These devices must be able to discover services dynamically and share them safely, taking into account ad-hoc networks requirements such as limited processing and communication power, decentralised management, and dynamic network topology, among others. Legacy solutions fail in addressing these requirements. In this paper, we propose a new service discovery protocol with security features, the Secure Pervasive Discovery Protocol. SPDP is a fully distributed protocol in which services offered by devices can be discovered by others, without a central server. It is based on an anarchy trust model of PKI and on existing protocols. This way it provides location of trusted services, protection confidential information, secure communications, identification between devices, and service access control. Keywords — Ad-hoc networks, service discovery protocol, security, trust. I.

The integration of Bluetooth service discovery protocol (SDP), and GPRS internet connectivity into phones provides a simple yet powerful infrastructure for accessing services in nomadic environments. In this paper, we discuss the design and implementation of SDIPP, a protocol for provisioning services on Smart Phones. Although several service discovery protocols have been proposed earlier, such as SLP, Jini, UPnP, Salutation, they all have their own infrastructure requirements and target audiences. Bluetooth SDP is an on-the-fly service discovery protocol. However, it is not nearly as powerful as its counterparts. SDIPP works by augmenting Bluetooth SDP with web access and personalization. Payment of services has been overlooked in the protocols proposed earlier. SDIPP provides a novel protocol for anonymous payment, based on the idea of Millicent scrips. We have implemented a few services to illustrate our protocol. We report on our experiences and experimental results. In particular, we analyze and provide an application level solution to the Bluetooth inquiry clash problem that was discovered in the process. 1

Service Discovery as an essential element in pervasive computing environments is widely accepted. Much research on service discovery has been conducted, but privacy and security have been ignored and may be sacrificed. While it is essential that legitimate users should be able to discover services, it is also necessary that services be hidden from illegitimate users. Since service information, service provider’s information, service requests, user presence information, and user’s identities may be sensitive, we may want to keep them private during service discovery processes. There appears to be no existing service discovery protocols that solve these problems. We present a user-centric model, called PrudentExposure, which exposes minimal information privately and securely. Users and service owners exchange code words in an efficient and scalable form to establish mutual trust. Based on the trust, secure service discovery sessions are set up. The model is further improved to counter attacks. We analyze the mathematical properties of our model, formally verify our security protocol, and measure the performance of our prototype system.

Abstract — Emerging service-oriented architectures are pushing towards on-demand and “on the fly ” application and business process composition. In order to support service composition, the underlying infrastructure must provide a facility for on-demand discovery of services and service components. Discovery becomes challenging when services span different networks and/or discovery domains. For inter-domain discovery to be achieved independently of domain-specific service discovery technologies, a middleware is needed to interface between the different discovery systems. In this paper, we present a novel Open Service Discovery Architecture (OSDA) designed to serve as an efficient, scalable, and programmable middleware for cross-domain discovery. We demonstrate the implementation of OSDA using a set of mature technologies. I.

Securely accessing unfamiliar services in public environments using ad hoc wireless networks is challenging. We present a proxy-based approach that uses other existing network channels to set up a secure and trust relationship between communication parties to facilitate ad hoc wireless communications. Based on a service discovery protocol, our models achieve secure, trusted, anonymous, efficient, and economical communications between unfamiliar parties. Our protocols are formally verified using BAN logic. 1.

Abstract. The pervasive computing paradigm assumes an essentially dynamic model of interaction between devices that also motivates the need to discover the services offered by previously unknown parties at an early phase of these interactions. Whereas this assumption is at the heart of many pervasive computing protocols and systems, the necessity of securing service discovery and the complexity of this task have been largely underestimated, if considered at all. This paper discusses the implications of insecure service discovery in available systems and which security objectives should be pursued. The design space for introducing security features into a specific architecture, namely registry-based discovery systems, is then explored and assessed. 1.

Abstract. Mobile devices are inherently scarce in resources, necessitating the need to cooperate among them for performing tasks that cannot be done alone. This cooperation is in the form of services that are offered by other devices in the network. To get benefit from the services offered by other devices, they have to be discovered. Service Discovery Protocols (SDPs) are used for this purpose. This is an important area of research in mobile computing and ubiquitous computing. In this paper twelve SDPs for multihop mobile ad hoc networks are analyzed with respect to their service discovery architectures, management of service information, search methods, service selection, methods for supporting mobility and service description techniques, Among these the most important aspect is the service discovery architecture as this affects other aspects of the service discovery. In this paper the service discovery architectures are categorized in four groups namely directory-based with overlay support architecture, directory-based without overlay support architecture, directory-less with overlay support architecture and directory-less without overlay support architecture. The management of service information and search methods mainly depend on the type of service discovery architecture. It is found that mobility support and service selection methods are independent of the SDP architecture. Also the description of services is found to be independent of the SDP architectures. Mostly the services are described using XML or the extensions of XML. At the end of the paper open issues and areas of further research are discussed.

Smart Phone is a recently emerged technology that supports Java program execution and provides both shortrange wireless connectivity (Bluetooth/IrDA) and Internet connectivity (GPRS/3G). Smart Phones represent the first viable ubiquitous computing devices because they are becoming an integral part of our daily life. Although these phones are closed systems with limited resources, we believe that a multitude of distributed applications in which Smart Phones act as peers in ad hoc networks can be developed. To realize the potential, there is a need for a middleware that supports such applications and a systematic study of the communication/computation trade-offs. The middleware should provide functionality to support service execution, discovery and migration and should be able to score well on three criteria: portability, security, and performance. To achieve this goal, we have implemented and evaluated Split Smart Messages (SSM), a lightweight middleware architecture similar to mobile agents, that exploits dual connectivity on Smart Phones. Services can be executed, discovered, and migrated on top of the SSM middleware. To facilitate portability, we have designed an execution migration scheme that works on top of unmodified Java virtual machines. To improve upon security while preserving performance, code is uploaded to and downloaded from a trusted web server, while data and state are transferred across the local network. We have implemented an SSM prototype on Sony Ericsson P800/P900 Smart Phones and compared its performance with that achieved on HP iPAQ PDAs.

Abstract. Advances in telecommunication and wireless systems together with the increasing diffusion of portable devices are enabling a pervasive and ubiquitous computing infrastructure for service provisioning, where mobile users expect to access the needed data from ubiquitous attachment points and require context-aware services, i.e., services that can adapt provided results to changing context information, such as variations in user relative position, in user requirements, and in locally available resources. A crucial requirement for the provisioning of context-aware services is the dynamical retrieval and interaction with local resources, i.e., discovery. Traditional discovery solutions, which are essentially based on the exact matching of syntactic patterns, like for