Abstract— Mobile environments, the Web, services, semantics, converge in the physical world forming a shared communication sphere. To ensure context-enabled interoperation on service platforms in such a sphere, developers need to have a shared specification of objects belonging to the sphere and their roles. We present context acquisition, context representation, context enabling and use in mobile service platforms, outline the main ontological enablers of the shared communication sphere, and illustrate their added value with a scenario. Index Terms— context awareness, service platforms, ontologies, Internet, WWW, mobile applications I. INTRODUCTION HIS paper includes a presentation of ideas on how a mobile service platform, specifically, the platform being designed in the IST project SPICE can utilize and benefit from the context information arriving from heterogeneous context sources (such as physical sensors, ontology-enabled profiles, WWW/Internet, system data, etc.). The motivation of the work is to attain integration of the state of the art context acquisition and representation practices on mobile service platforms, making the corresponding components mutually interactive within and across service platforms, and enabling and use of context in building services and applications. By context we understand any information that can be used to characterize the situation of entities (i.e., whether a person, place or object) that are considered relevant to the interaction Manuscript received April 16, 2006. This work has been partly supported by European Commission under IP SPICE (IST-2006-027617). A. V. Zhdanova is with the Centre for Communication Systems Research, University of Surrey, Guildford, GU2 7XH, UK (phone: 44-1483-684745; fax: 44-1483-686011; e-mail: a.zhdanova@surrey.ac.uk). J. Zoric is with Service Platform Group, Telenor R&D, Trondheim, Norway (e-mail: josip.zoric@telenor.com). M. Marengo is with Telecom Italia, Torino, Italy (e-mail: marco.marengo@telecomitalia.it). H. van Kranenburg is with Telematica Instituut, Enschede, The Netherlands (e-mail: Herma.vanKranenburg@telin.nl). N. Snoeck is with Telematica Instituut, Enschede, The Netherlands (e- mail: Niels.Snoeck@telin.nl). M. Sutterer is with University of Kassel, Kassel, Germany (email: michael.sutterer@comtec.eecs.uni-kassel.de). C. Räck is with FOKUS, Fraunhofer, Berlin, Germany (e-mail: christian.raeck@fokus.fraunhofer.de). O. Droegehorn is with University of Kassel, Kassel, Germany (e-mail: Droegehorn@uni-kassel.de). S. Arbanowski is with FOKUS, Fraunhofer, Berlin, Germany (e-mail: stefan.arbanowski@fokus.fraunhofer.de). between a user and an application, including the user and the application themselves. Context is typically the location, identity and state of people, groups and computational and physical objects [3]. In particular, context comprises a subset of available information that is relevant to a specific event. By a service platform we understand the following: • an environment for services and applications to operate in, standardized access to the data of system and physical communication layers, • a provider of service enablers, i.e., components that make creation of other services easier and provide end-users with a transparent service access across heterogeneous networks and domains: o specific functionality support: call control, instant messaging, streaming, location retrieval, etc. o general service management: service discovery, composition, brokering, mediation, QoS management, AAA/A4C management, etc. • an aggregator, manager and provider of the context data coming from outside of the system (e.g., from the Web) and physical layers. This paper is organized as follows. Section 2 focuses on context acquisition, and Section 3 focuses on context representation/formalization. Motivating scenario, context enabling and its use in services and service platform are described in Section 4. Section 5 concludes the paper. II. CONTEXT ACQUISITION In this section, we analyze context acquisition for service platforms from the perspectives of the physical world, enabling systems and the Internet/WWW systems. A. Sensors/Physical World The typical physical world context information acquired from sensors can be classified into seven categories: movement/acceleration, light, proximity, audio, temperature, mechanical force, and humidity [1]. Whereas much research on context acquisition from sensors focuses on operating with information related to movement and location, some areas of context acquisition are not sufficiently covered. Such areas include acquisition of information of visual character (primarily due to the complexity of its acquisition), information which is acquired by humans via their senses of taste and smell, and human emotions and mood. Addressing the challenges above, i.e., Context Acquisition, Representation and Employment in Mobile Service Platforms Anna V. Zhdanova, Josip Zoric, Marco Marengo, Herma van Kranenburg, Niels Snoeck, Michael Sutterer, Christian Räck, Olaf Droegehorn, Stefan Arbanowski T