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.

This paper proposes a new scheme for efficient dissemination and discovery of service information in mobile ad hoc networks. By extending Bloom filter-based service summarization scheme, our discovery middleware layer also encodes distance to services in summarization filters. By having the distance information gradually attenuated during its propagation, our proposal enables faster discovery of services with a limited amount of advertisement traffic. Categories and Subject Descriptors C.2.1 [Computer-Communication Networks]: Network

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.

Abstract. This paper explores service composition in pervasive environments with a focus on dynamic service selection. Service orientation offers the dynamism and loose coupling needed in pervasive applications. However, contextaware service composition is still a great challenge in pervasive computing. Service selection has to deal with dynamic contextual information to enable context-aware behaviors to emerge from the environment. This paper describes how to add dynamic contextual service ranking mechanisms to the serviceoriented OSGi framework and further discusses service re-composition decisions. 1

Abstract. Providing service discovery in an efficient and scalable way in ad hoc networks is a challenging problem, in particular for multihop scenarios, due to the large number of potential participant nodes and the scarce resources in these networks. In this paper, we propose and evaluate an approach to mitigate the reply implosion problem in querybased service discovery protocols for multihop mobile ad hoc networks. Our simulation results show the scalability and efficiency of the proposed solution. We demonstrate that the proposed scheme considerably reduces the number of transmissions without compromising the efficiency of the service discovery in scenarios of pedestrian mobility. 1

Abstract—In this paper, we show our early efforts to

Abstract — Beyond 3G (B3G) environments bring new challenges for mobile service platforms, as they strive to support new interaction models between mobile users and to leverage the services deployed in the environment. For users to discover and access the networked services, an innovative solution is required that overcomes both the heterogeneity of the runtime environments (and therefore protocols) of the clients and services, and the limited interconnectivity between the different networks available at a location. We proposed the MUSDAC middleware platform that interoperates with existing service discovery protocols and manages the dissemination of service information in dynamic multi-network compositions. In this paper, we present our assessment of the scalability of the MUSDAC platform, focusing on the dissemination of discovery requests. We in particular analyze the impact of the network dynamics, of the maximum hop number and of the network interconnectivity level. Index Terms — Interoperability, heterogeneous networks, scalability, service discovery, I.

Coordinating entities in a networked environment has always been a significant challenge for software developers. In recent years, however, it has become even more difficult, because devices have increasingly rich capabilities, combining an ever larger range of technologies (networking, multimedia, sensors, etc.). To address this challenge, we propose a language-based approach to covering the life-cycle of applications coordinating networked entities. Our approach covers the characterization of the networked environment, the specification of coordination applications, the verification of a networked environment and its deployment. It is carried out in practice by a domain-specific language, named Pantaxou. This paper presents the domain-specific language Pantaxou, dedicated to the development of applications for networked heterogeneous entities. Pantaxou has been used to specify a number of coordination scenarios in areas ranging from home automation to telecommunications. The language semantics has been formally defined and a compiler has been developed. The compiler verifies the coherence of a coordination scenario and generates coordination code in Java.

Telecomunicació. Projecte final de carrera, 69p.

Meta service discovery is used to find and select a service discovery mechanism by context. As multiple service discovery mechanisms (SDM) proliferate across various administrative domains, mobile devices will require a way to locate and select the appropriate mechanism according to the context of the mobile device, such as network domain, location, protocol, and application. We define Meta Service Discovery and explain the motivation for it. We describe our results in building a Meta Service Discovery capability on three existing DHTs and integrated into a new broadcast-oriented SDM. Finally, we analyze the sizing and distribution of DHT entries, including hash distribution of SDM entries according to a geographic population-density scheme. 1.