WS-Discovery

Abstract: This work proposes a Web Service (WS) discovery model in which the functional and non-functional requirements are taken into account during service discovery. The proposed infrastructure includes a set of services and tools to support an integrated WS discovery and selection solution. A mechanism is introduced that supports three different functional policies. It is able to take advantage of quality information located into a Web Service description language description file that might be located in a proprietary universal description, discovery and integration registry server or in an independent URL. Moreover, it implements a database supported WS intermediary (Broker) that it is also possible to store quality of service (QoS) information for WSs. A selection module is also presented that delivers the WS that maximizes the value of QoS characteristics among others with the same functionality. An experimental prototype is presented and evaluated in the scenario of air ticket issuing WS selection.

Abstract: The success of the Web Service (WS) paradigm has led to a proliferation of available WSs, which are advertised in WS registries. While sophisticated semantic WS discovery algorithms are operating on these registries to return matchmaking results with high precision and recall, many functionally-equivalent WSs are returned. The solution to the above problem comes in terms of semantic QoS-based description and discovery of WSs. We have already presented a rich and extensible ontology language for QoS-based WS description called OWL-Q. We have also proposed a semantic QoS metric matching algorithm. Based on this algorithm, we have extended a CSP-based approach for QoS-based WS discovery. In this paper, we firstly analyze the evolution of OWL-Q and its extension with SWRL rules, we propose a modification to the metric matching algorithm and we show the way the metric alignment process takes place. Then we propose two novel semantic QoS-based WS Discovery algorithms that return matches even for over-constrained QoS-based WS requests. The first one deals with unary constraints while the second one is more generic. Finally, implementa- tion aspects of our QoS-based WS discovery system are discussed.

Abstract: This specification defines a discovery protocol to locate services. In an ad hoc mode of operation, probes are sent to a multicast group, and target services that match return a response directly to the requester. To scale to a large number of endpoints and to extend the reach of the protocol, this protocol defines a managed mode of operation and a multicast suppression behavior if a discovery proxy is available on the network. To minimize the need for polling, target services that wish to be discovered send an announcement when they join and leave the network.

Abstract: Dynamic and self-organizing systems like those found in ubiquitous computing or semantic web based scenarios raise numerous challenges regarding trust and privacy. Service discovery is a basic feature of SOA deployment in such systems, given that entities need to locate services they can describe but that they do not necessarily know. PKI based solutions to securing this mechanism, which require a preliminary key distribution, are therefore rendered awkward and contrived. In contrast, the new concept of Attribute Based Encryption, derived from Identity Based Encryption schemes, makes it possible to create secret communication channels with unknown services based solely on some attributes that are part of their description and in a decentralized fashion, that is, without the introduction of any additional trusted third party like a registry. This paper discusses how such a scalable solution to enabling secure and decentralized discovery protocols can be implemented and put to use. After reviewing the security properties that are expected, the paper then goes on to detail how to extend the WS-Discovery Web Service protocol with such mechanisms. Preliminary experimental results based on an implementation of this extended protocol are finally presented.