Query processing in traditional information management systems has moved from an exact match model to more flexible paradigms allowing cooperative retrieval by aggregating the database objects' degree of match for each different query predicate and returning the best matching objects only. In peer-to-peer systems such strategies are even more important, given the potentially large number of peers, which may contribute to the results. Yet current peer-to-peer research has barely started to investigate such approaches. In this paper we will discuss the benefits of best match/top-k queries in the context of distributed peer-to-peer information infrastructures and show how to extend the limited query processing in current peer-to-peer networks by allowing the distributed processing of top-k queries, while maintaining a minimum of data traffic. Relying on a super-peer backbone organized in the HyperCuP topology we will show how to use local indexes for optimizing the necessary query routing and how to process intermediate results in inner network nodes at the earliest possible point in time cutting down the necessary data traffic within the network. Our algorithm is based on dynamically collected query statistics only, no continuous index update processes are necessary, allowing it to scale easily to large numbers of peers, as well as dynamic additions/deletions of peers. We will show our approach to always deliver correct result sets and to be optimal in terms of necessary object accesses and data traffic. Finally, we present simulation results for both static and dynamic network environments.

We present enhancements for UDDI / DAML-S registries allowing cooperative discovery and selection of Web services with a focus on personalization. To find the most useful service in each instance of a request, not only explicit parameters of the request have to be matched against the service offers. Also user preferences or implicit assumptions of a user with respect to common knowledge in a certain domain have to be considered to improve the quality of service provisioning. In the area of Web services the notion of service ontologies together with cooperative answering techniques can take a lot of this responsibility. However, without quality assessments for the relaxation of service requests and queries a personalized service discovery and selection is virtually impossible. This paper focuses on assessing the semantic meaning of query relaxation plans over multiple conceptual views of the service ontology, each one representing a soft query constraint of the user request. Our focus is on the question what constitutes a minimum amount of necessary relaxation to answer each individual request in a cooperative manner. Incorporating such assessments as early as possible we propose to integrate ontologybased discovery directly into UDDI directories or query facilities in service provisioning portals. Using the quality assessments presented here, this integration promises to propel today’s Web services towards an intuitive user-centered service provisioning.

Abstract. Advanced personalization techniques are required to cope with novel challenges posed by attribute-rich MPEG-7 based digital libraries. At the heart of our deeply personalized news dissemination system P-News is one extensible preference model that serves all purposes, preventing impedance mismatches between the various stages: User modeling by structured preference patterns, automatic query expansion including ontologies, preference query evaluation by Preference XPath including nested preferences on categorical data, quality assessment of query results, personalized notification and news syndication. 1

Abstract. The vision of a mobile Web in which the computing environment will be composed of various devices that are carried by different users as they go through their daily routine might soon become a reality. In this context, Web services and the Semantic Web are already recognized as important building blocks. On the other hand, so far only little work has been done to support the discovery and selection of semantically enriched Web services on mobile terminals. In this paper we present a graphical toolbox for preference-based service discovery on tiny mobile devices. Our prototypical toolbox is developed as an extension of the Protégé OWL plugin and consists of a component called MOBIONT responsible for service matchmaking and preference relaxation together with an emulator for different mobile devices called MOBIXPL. Our work aims to serve as an open platform in order to gain experiences with different discovery strategies as well as mobile end-user interfaces. 1

Abstract. The increasing variety of mobile multimedia services raises the need for mechanisms to select those services whose capabilities best match individual user requirements. In this paper we present an advanced concept for service personalization in next-generation IP-based mobile systems based on the notion of user preferences. The described concept features several enhancements for personalization, including the intuitive modeling of user preferences, the construction of complex preference terms from basic preference expressions and a stepwise refinement of profiles and preferences. We describe this solution applied to the signaling mechanism of the Session Initiation Protocol (SIP), which is the protocol suite for application control in current IP-based mobile communication systems such as UMTS. In particular, our preference concept for personalized service management extends the conventional SIP preference modeling methods proposed so far: a preference order on the available service features is introduced that accounts for the specific demands of a user without a numerical ranking of features. We show how base preferences can be intuitively combined to complex preference expressions and explain how these relate to standard SIP feature preferences. 1

Growing numbers of pervasive devices are gaining access to the Internet. However, much of the existing rich multimedia content cannot be handled by mobile client devices with limited communication, processing, storage and display capabilities. In this paper, we propose new ways to enhance the universal access to multimedia content through Web Services and Semantic Web concepts. A semantic-based personalized delivery concept is drafted that makes use of these emerging technologies together with rather classical multimedia transcoding ideas. Instead of large, monolithic portal applications designed for multi-purpose adaptation and a single-source delivery, we propose to shift multimedia adaptation functionality to a portfolio of adequately selected Web Services. Web Services accessible through standard interfaces that allow for multimedia format conversion and composition can allow for a more flexible, application-independent adaptation and thus ease multimedia service provisioning essentially.

When moving from monolithic applications towards service-oriented multimedia frameworks, the composition of Web services to form complex multimedia workflows becomes a demanding problem. Especially mobile devices require a flexible composition strategy as they often have to move computationally complex or power-demanding tasks to powerful servers. Such a strategy also has to consider the changing environment due to movements of the device and it has to adapt to device-specific characteristics, e.g., the current battery level. Hence, mobile devices experience problems beyond the mere question of services ’ availability or successful execution. We propose the E 2 Mon algorithm that monitors the execution chain of Web services and gracefully recovers from failures of individual services and network-specific or device-specific alarms. The sophisticated control flow dynamically chooses the quality-optimal and cost-optimal composition of available services handling both successive and parallel service execution. 1

Knowledge representation has a long tradition in logic and philosophy.

The process of decision making regarding the outsourcing of various tasks in an enterprise’s value chain involves consideration of a number of important economic trade offs. Outsourcing decisions in the past have typically been of a strategic nature involving long-term commitment. However, given the emerging technologies of Web services and the growing variety of service providers it seems feasible to utilize the Internet’s ubiquity and pervasiveness for outsourcing at least more simple tasks dynamically in a call-by-call manner. However, to make the required decisions in each instance without having to manually assess the quality of each offer an automatic quality assessment based on a mutual service level agreement is essential. In this paper we will investigate the necessary mechanisms and demonstrate their feasibility in a real world use case scenario.

We demonstrate an early prototype from our work in the field of semantic-based service discovery on mobile terminals. Main contributions are in support for browsing service ontologies and the cooperative discovery of services based on an intuitive preference model. The prototype is based on Semantic Web as well as Web service technology and currently realized as plug-in to Protégé.