Extension Of WSDL Research Articles

A Web Service Framework Supporting Multimedia Streaming

The transfer of streaming data is not well supported by current web services standards. To include multimedia streaming support in the web services domain, this paper presents a novel multimedia streaming web services framework for the transfer of streaming multimedia content. First, the framework includes an implementation of a query service for publishing a description of the multimedia content that is input to or output from a multimedia web service. This query service is specified in an extension of WSDL. Using MPEG-7 metadata, content descriptions can be queried before the invocation of a multimedia web service. Second, two new MEPs and their SOAP HTTP bindings are created for the exchange of streaming data between two SOAP endpoints. The implementations of these new MEPs use the MIME multipart/related structure and MTOM packaging when transferring the multimedia packets as SOAP messages. To reduce the transfer overhead introduced by the packaging method, this paper investigated extensively the application of various compression schemes for the SOAP messages as well as for the packaging of the binary packet data. Experiments show that the proposed framework can achieve a performance comparable to a simple HTTP multimedia streaming method.

Template-based matching algorithm for dynamic web services discovery

The expansion of web service provider's number over the web has motivated the research community to invest in web service discovery area. However, in order to efficiently identify appropriate services, web services requesters should express their requests in rich, standard and machine-readable manner. In this context, we propose the use of a Service Request Template based on SAWSDL and WS-Policy standards. We use SAWSDL language which constitutes an extension of WSDL to express both functional and semantic needs, while we use WS-Policy framework to specify both non-functional requirements and user's preferences. We think that the proposed template would make it possible to overcome problems due to the heterogeneity between web services requests and published web services when executing discovery process. To perform efficient service discovery, we develop a structure-based matching algorithm that offers three mechanisms: semantic, data types and policy matching.

A model-driven method for describing and predicting the reliability of composite services

Service-oriented computing is the prominent paradigm for viewing business processes as composed of functions provided by modular and standardized services. Web services are the building blocks for the application of service-oriented computing on the Web and provide the necessary support for the consolidation of multiple services into a single composite service corresponding to the overall process. In such a context, service providers are strategically interested in both describing the quality of service (QoS) characteristics of offered services, to better qualify their offer and gain a significant advantage in the global marketplace, and predicting the level of QoS that can be offered to service consumers when building composite web services that make use of services managed by various service providers. This paper illustrates a model-driven method to automatically describe and predict the QoS of composite web services specified by use of business process execution language (BPEL). The paper specifically addresses the reliability characteristic of the QoS. The proposed method is founded on Q-WSDL, a lightweight WSDL extension for the description of the QoS characteristics of a web service, and exploits Q-WSDL to annotate reliability data onto a BPEL-based UML model of the composite service. The UML model is then used to predict and describe the reliability of the composite web service. The proposed method is illustrated by use of an example application that deals with a composite web service for the migration of PSTN telephone numbers.