Sudhir Agarwal

Annotation, composition and invocation of semantic web services

The way that web services are currently being developed places them beside rather than within the existing World Wide Web. In this paper, we present an approach that combines the strength of the World Wide Web, viz. interlinked HTML pages for presentation and human consumption, with the strength of semantic web services, viz. support for semi-automatic composition and invocation of web services that have semantically heterogeneous descriptions. The objective we aim at eventually is that a human user e.g. a consultant or an administrator can seamlessly browse the existing World Wide Web and the emerging web services and that he can easily compose and invoke Web services on the fly. This paper presents our framework, OntoMat-Service, which trades off between having a reasonably easy to use interface for web services and the complexity of web service workflows. It is not our objective that everybody can produce arbitrarily complex workflows of web services with our tool, the OntoMat-Service-Browser. However, OntoMat-Service aims at a service web, where simple service flows are easily possible-even for the persons with not much technical background, while still allowing for difficult flows for the expert engineer.

Automatic matchmaking of web services

Web services help in achieving increased automation across organizational boundaries. In this paper, we present an approach for annotating WSDL documents with semantically rich descriptions. We also present an algorithm that considers such annotations in addition to just the types of input and output parameters. Our matchmaking algorithm not only returns match/no-match answers but in case of a match a set of conditions under which a Web service offers the desired functionality

SMART - a semantic matchmaking portal for electronic markets

Searching and comparing products in electronic markets is still a challenging problem. On one hand, the expressive power of the search mechanisms offered by the existing electronic markets is too limited. On the other hand, the price is mostly the only criterium of comparing the results with each other. In this paper, we introduce SMART (semantic matchmaking portal) to improve searching and comparing products in electronic markets. Therefore, we present a novel matchmaking approach based on fuzzy descriptions that provide a more expressive search mechanism that is closer to human reasoning and aggregates multiple search criteria to a single value (ranking of an offer relative to the query), thus enabling better selection of offers that should be considered for the negotiation.

Automatic Matchmaking of Web Services

Web services help in achieving increased automation across organizational boundaries. In this paper, we present an approach for annotating WSDL documents with semantically rich descriptions. We also present an algorithm that considers such annotations in addition to just the types of input and output parameters. Our matchmaking algorithm not only returns match/no-match answers but in case of a match a set of conditions under which a web service offers the desired functionality.

Access control for semantic Web services

In this paper, we present an approach to enable access control for semantic Web services. Our approach builds on the idea of autonomous granting of access rights, decision making based on independent trust structures and respects privacy requirements of the users. Our framework allows the specification and computation of complex access control policies in a manageable and efficient way. Therefore, our approach is useful not only in Web services based applications (typically client-server architecture) but also in peer-to-peer and agent-based applications.

Surfing the service web

The way that web services are currently being developed places them beside rather than within the existing World Wide Web. In this paper we present an approach that combines the strength of the World Wide Web, viz. interlinked HTML pages for presentation and human consumption, with the strength of semantic web services, viz. support for semi-automatic composition and invocation of web services that have semantically heterogeneous descriptions. The objective we aim at eventually is that a human user can seamlessly surf the existing World Wide Web and the emerging web services and that he can easily compose and invoke Web services on the fly without being a software engineer. This paper presents our framework, OntoMat-Service, which trades off between having a reasonably easy to use interface for web services and the complexity of web service workflows. It is not our objective that everybody can produce arbitrarily complex workflows of web services with our tool, the OntoMat-Service-Surfer. However, OntoMat-Service aims at a service web, where simple service flows are easily possible - even for the persons with not much technical background, while still allowing for difficult flows for the expert engineer.

Towards practical semantic web service discovery

Service orientation is a promising paradigm for offering and consuming functionalities within and across organizations. Ever increasing acceptance of service oriented architectures in combination with the acceptance of the Web as a platform for carrying out electronic business triggers a need for automated methods to find appropriate Web services. Various formalisms for discovery of semantically described services with varying expressivity and complexity have been proposed in the past. However, they are difficult to use since they apply the same formalisms to service descriptions and requests. Furthermore, an intersection-based matchmaking is insufficient to ensure applicability of Web services for a given request. In this paper we show that, although most of prior approaches provide a formal semantics, their pragmatics to describe requests is improper since it differs from the user intention. We introduce distinct formalisms to describe functionalities and service requests. We also provide the formal underpinning and implementation of a matching algorithm.

Making Web services tradable

In service-oriented architectures, applications are developed by incorporating services which are often provided by different organizations. Since a service might be offered under different configurations by various different organizations, sophisticated service selection and negotiation algorithms are required. Policies capture the conditions under which services are offered or requested and thereby constrain the negotiation space. However, current policy languages are ill-suited to realize beneficial trade-offs within a negotiation, since they support only Boolean decisions and cannot capture all relevant service information. Therefore, we present a novel policy language in this work that provides two main contributions: (i) we enable the specification of constraints on functional as well as non-functional properties of Web services. The functional properties include data objects and the behaviour, whereas the non-functional properties include QoS attributes. (ii) Given such constraints, we show how the concept of utility function policies can be used to define cardinal preferences over functional as well as non-functional properties. This is required to rank Web service offers, define their prices, and consequently to realize automated negotiations between service providers and requesters.

Managing Quality of Human-Based eServices

Modern business strategies consider Web-based outsourcing of microjobs to the masses. Respective business activities are however difficult to manage. Traditional approaches of covering human tasks in business processes build on assumptions of limited process scale and closed organizational models that are not valid in crowdsourcing scenarios. Web services have been proposed as a means to represent human tasks that allow leveraging interaction, brokerage and composition capabilities of SOC for human interaction management. In this paper we argue that crowdsourcing requires considering qualitative constraints and sketch a platform for managing the quality of human-based eServices.

Specification of access control and certification policies for semantic web services

Web service providers specify access control policies to restrict access to their Web services. It turned out, that since the Web is an open, distributed and dynamic environment, in which a central controlling instance cannot be assumed, capability based access control is most suitable for this purpose. However, since practically every participant can certify capabilities defined in his/her own terminology, determining the semantics of certified capabilities and the trustworthiness of certification authorities are two major challenges in such a setting. In this paper, we show, (1) how certification authorities and their certification policies can be modeled semantically (2) how Web service providers can specify and check the consistency of their access control policies and (3) how end users can check automatically, whether they have access to a Web service.