Effective Web Service Discovery in Mobile Environments Khalid Elgazzar, Hossam Hassanein, Patrick Martin School of Computing, Queen’s University, Canada {elgazzar, hossam, martin}@cs.queensu.ca Abstract—Recent advancements in the design of mobile devices and wireless technologies have produced a successful coupling of mobile devices and Web services, where mobile devices can be a service provider or a consumer. However, finding relevant Web services that match requests remain a major hindrance to its booming. The challenges facing Web service discovery are further magnified by the stringent constraints of mobile devices, and the inherit complexity of wireless heterogeneous networks. While significant research has focused on service discovery protocols in isolation, they mostly lack a holistic capacity to address the different limitations collectively. We introduce a novel discovery framework that addresses all aspects of mobile Web service discovery, yet does not jeopardize the efficiency requirement for this discovery; especially as an application run in resource- constrained environments. Index Terms—mobile Web services, Web service discovery, service discovery framework, mobile devices I. I NTRODUCTION Service Oriented Architecture (SOA) [1] is a vision of developing software applications that can be composed of networked functionalities that are capable of interacting with each other automatically. SOA offers the promise of robustness and agility by supporting software reuse, loose coupling, flexible design, and interoperability between heterogeneous applications. With the emergence of the Mobile Internet (MI) and the constantly expanding mobile user base, the notion of networked functionalities helps end-users with limited re- sources to perform complicated tasks on high-end machines over the network. Web services implement the concepts of SOA to enable “software as a service”, which delivers software services over the network using technologies such as XML. Web services, however, have neither achieved the antic- ipated wide spread use, nor dominated Web applications development. Web services have, so far, failed to match the burst expansion of the Web. A main reason is the inefficiency of Web service discovery. That is, the ability for the user to find Web services that meet his/her needs and are appropriate for the current context [2]. The standard Web service development cycle includes description, discovery, and invocation (remote execution) [3]. Web service discovery in particular, is a key enabler to the adoption of Web services technology as a computing paradigm. With the emergence of new generations of smartphones and high-end mobile devices, both equipped with extraordinary features, users became capable of running sophisticated Web applications. Furthermore, the unprecedented advancements of wireless technologies influence mobile users to become highly interested in the Mobile Internet. With the limitations existing in wireless networks and the limited resources of mobile devices, Web service discovery becomes even more difficult, and hence, challenging. Broadly speaking, current service discovery techniques are fundamentally designed for static and wired environments. Most of the existing discovery approaches lack the compre- hensive understanding of both mobile devices and wireless networks limitations, which makes these approaches incapable of efficient and reliable discovery in a mobile scenarios. In this paper, we introduce a novel discovery framework that addresses all aspects of mobile Web service discovery in resource-constrained environments. For the various aspects of the framework, we identify approaches that could potentially be applied from current research. The contributions of this paper can be summarized as follows: • We provide an overview of existing Web service dis- covery approaches and point out their limitations in mobile environments. As well, we identify the essential requirements for a successful Web service discovery in resource-constrained environments. • We propose a generic Web service discovery framework that can be used in a general Web service environment, but more specifically for mobile domains and resource- constrained environments. The framework can be imple- mented in client/server or P2P networks with sufficient robustness to implement components where they would perform most efficiently. • We propose a novel request submission protocol that identifies the available service providers as well as the language used to describe the services they offer before submitting the service request. The remainder of this paper is organized as follows. Section II outlines related research. Section III gives a brief back- ground on Web service descriptions. Section IV discusses the current discovery approaches, points out the limitations, and identifies the essential requirements for efficient discovery in mobile environments. Section V describes the proposed framework and relevant research efforts that are applicable for each component. In Section VI we present a use-case scenario to illustrate how the proposed framework can be applied. Finally, Section VII concludes the paper and outlines future research avenues. 7th IEEE International Workshop on Performance and Management of Wireless and Mobile Networks P2MNET 2011, Bonn, Germany 978-1-61284-928-7/11/$26.00 ©2011 IEEE 697