The paper proposes a novel distributed service discovery protocol for pervasive environments. The protocol is based on the concepts of peer-to-peer caching of service advertisements and group-based intelligent forwarding of service requests. It does not require a service to be registered with a registry or lookup server. Services are described using the Web Ontology Language (OWL). We exploit the semantic class/subClass hierarchy of OWL to describe service groups and use this semantic information to selectively forward service requests. OWL-based service description also enables increased flexibility in service matching. We present simulation results that show that our protocol achieves increased efficiency in discovering services (compared to traditional broadcast-based mechanisms) by efficiently utilizing bandwidth via controlled forwarding of service requests.

/pdf/toward-distributed-service-discovery-in-pervasive-computing-1yme0sc3i7.pdf

Toward Distributed service discovery in pervasive computing environments

Distributed hash tables (DHTs) have proven to be a novel and efficient platform for building a variety of scalable and robust distributed applications like content sharing and location in the Internet. Similar to those in the Internet, distributed applications and network services in mobile ad hoc networks (MANETs) can potentially benefit from the deployment of a DHT. However, bandwidth limitations, node mobility, and multi access interference pose unique challenges to deploying such DHTs in MANETs. In this paper, we first study how to efficiently implement DHTs in MANETs. We explore two disparate design options: the simple approach of directly overlaying a DHT on top of a MANET multi-hop routing protocol, and Ekta which integrates a DHT with a multi-hop routing protocol at the network layer. Second, we examine the efficiency of DHT substrates in supporting applications in MANETs by examining the performance of a resource discovery application built on top of Ekta with one that directly uses physical layer broadcast. Such a study answers the fundamental question of whether a DHT substrate can be more efficient in supporting applications than a physical layer broadcast-based protocol, since in MANETs, DHT protocols effectively rely on physical layer broadcast to discover and maintain routes.

/pdf/ekta-an-efficient-dht-substrate-for-distributed-applications-337obbzkq3.pdf

Ekta: an efficient DHT substrate for distributed applications in mobile ad hoc networks

This paper presents a piecewise framework for network awareness service (NAS) for wireless/mobile pervasive computing. We investigate how piecewise consideration of wired and wireless elements of the framework architecture benefits service advertisement and discovery and network-awareness techniques. We also discuss scalability of the NAS framework with respect to platform computing capabilities. The framework is suitable for a wide range of computing devices, from powerful ones with multi-tasking operating systems (OS) to small ones with lightweight OS. Case studies applying the NAS framework to sensor monitoring in home networks and data streaming in pervasive multimedia computing are presented. The analytical results on the performance of the NAS framework in these case studies show that it has significant advantages over traditional network-awareness frameworks in terms of reducing wireless bandwidth consumption and saving battery energy of mobile devices.

/pdf/piecewise-network-awareness-service-for-wireless-mobile-12rcyxrz8t.pdf

Piecewise network awareness service for wireless/mobile pervasive computing

In this paper, we propose GSR: a new routing and session management protocol for ad-hoc networks as an integral part of a service discovery infrastructure. Traditional approaches place routing at a layer below service discovery. While this distinction is appropriate for wired networked services, we argue that in ad-hoc networks this layering is not as meaningful and show that integrating routing with discovery infrastructure increases system efficiency. Central to our protocol is the idea of reusing the path created by the combination of a service discovery request and a service advertisement for data transmission. This precludes the need to use separate routing and discovery protocols. GSR also combines transport layer features and provides end-to-end session management that detects disconnections, link and node failures and enables service-centric session redirection to handle failures. This enables GSR to accommodate service-centric routing apart from the traditional node-centric routing. We compare GSR with AODV in terms of packet delivery ratio, response time and average number of hops traveled by service requests as well as data. GSR achieves better packet delivery ratio with a minor increase of the average packet delivery delay.

/pdf/integrating-service-discovery-with-routing-and-session-4fpgyq1sp7.pdf

Integrating service discovery with routing and session management for ad-hoc networks

Common user applications (including web browsing and e-mail) cannot run in mobile ad-hoc networks (MANETs) before a method for name resolution is in place. While the Domain Name System (DNS) works well on the fixed Internet, it represents a centralized approach to name resolution, which is not suitable for MANETs. This article demonstrates that most existing reactive routing protocols do not have sufficient capabilities to support bandwidth-efficient name resolution. We propose a scheme to improve this deficiency of existing reactive routing protocols. We also investigate the trade-off between using fully distributed name servers and partially distributed name brokers (or name databases). We also propose a framework for name resolution in MANETs. Based on this framework, we finally suggest a complete solution to name resolution, which interoperates with DNS and multicast DNS (mDNS).

http://persons.unik.no/paalee/publications/NR-paper-for-ICT2003.pdf

Name resolution in mobile ad-hoc networks

Much of the current research in mobile networking investigates how to support a mobile user within an established infrastructure of routers and servers. Ad hoc networks come into play when no such established infrastructure exits. This paper presents a two-stage protocol to solve the resource discovery problem in ad hoc networks: how hosts discover what resources are available in the network and how they discover how to use the resources. This protocol does not require any established servers or other infrastructure. It only requires routing capabilities in the network.

Chih Chang

Papers

Resource Discovery in Ad hoc Networks