The Knowledge Management Lab
University of Toronto

Description

Web services are interoperable, standards-based software components that can be accessed over the Internet. They can be used as building blocks to construct applications whose functionality may be simple or complex. They are widely accepted in the IT industry -- leading IT companies such as Microsoft, Sun, Oracle, SAP and BEA support web services. And they are becoming widely accepted in business. Gartner Group expected 75 percent of enterprises with more than $100 million in annual revenue to use web services by 2002. Web services are self-contained, self-describing, modular, reusable applications that can be published, located, invoked and even brokered over the Internet. Web services are defined in terms of a stack of emerging XML-based open standards for service description (WSDL), invocation (SOAP), publication and discovery (UDDI, DISCO), and composition (WSFL).

Our goal in this research is to support the migration of existing software systems to web service-based architectures. In support of this goal, we are investigating several issues:

• Designing web service definition, publication, and composition languages. Although there are various emerging standards for all these languages, many improvements are needed and many issues remain unresolved.

• Wrapping software components into web services. Most web services come from existing software components rather than being written from scratch. We will investigate the wrapping of web services from various sources, such as HTML web sites, interface definitions of distributed software components such as CORBA and DCOM, and EJB remote objects.

• Composing web services. A major advantage of web services is that they can be composed dynamically over the web, relying only on the HTTP protocol. We will study service composition using XML schema inferences and semi-structured data integration techniques.

• Discovering web services. We propose to define a similarity metric for web services in terms of the structure of web service signatures and the semantic distance between tag names. Signature matching of web services will depend on XML schema matching, and the definition of semantic distance will use ontologies and other knowledge representation techniques.

• Brokering web services. To realize the ultimate power of web services, it must be possible for web services to dynamically collaborate and interoperate in order to produce new web services.  Our research aims to enable this through web service brokers which accept complex requests, locate relevant sub-services from the web, and use those services together to address an initial request.