Semantic Web Services: Hype or Reality Ling Liu College of Computing Georgia Institute of Technology

Web, Web Services and Semantic Web Services Web today:  Presents a computing architecture of the Web geared towards delivering information for human-browsing. Web Services:  Presents a computing architecture of the Web geared towards exchanging information between applications. Semantic Web Services:  Promises a computing architecture of the Web towards intelligently exchanging information between applications.

My Panel Statement Can semantic web services become a reality?  Semantic Web Services can play a critical role in the rapid deployment of service oriented applications.  However, this will happen only if the use of semantics will not add extra burden on both the developers and the users of Web services; And yet demonstrate real value in terms of productivity.

The History of AI Provides many examples of two weaknesses:  Over-promising by insiders Intelligent Agents, “a breakthrough in enthusiasm”  Over-optimism by outsiders [Henry S. Thompson, 2000] SWS: What should we learn  Risk: vulnerable to the same criticism

The History of KR The representation and exploitation of knowledge has been the ultimate grand challenge for Artificial Intelligence since its inception Human intelligence v.s. machine intelligence Lessons learned  Designing apparently expressive notations is easy, making them do actual work is much harder  designing an approach to KR without first designing an inference engine  can be ‘a waste of time’  User-friendly and Expressive  how to tradeoff [adopted from Henry S. Thompson 2000]

The Success Story of DBMSs Relational data model  Mechanisms for capturing simple but powerful semantics (more declarative)  Prevailed over Hierarchical data model and Network data model (more procedural) RDBMS: ANSI SPARC architecture Three Levels: External, Conceptual, Internal Binding between external and conceptual  Logical data independence Binding between conceptual and internal  Physical data independence

Web Services: an Analogy Location-independent distributed computing model  Functionality Facilitate rapid design and deployment of service oriented applications Enabling effective creation, execution, and composition, as well as automated discovery and classification, of Web services Productivity and Ease of Deployment  Three tier architecture User Level, Service Level, Execution Level Binding between user and service  Service Location Independence Binding between service and execution  Service Execution (interface/invocation) Independence

Web Services: On the Move Web Services as a Software Architecture Web Services as a Software Architecture  connect computers and devices with each other through the Web infrastructure and exchange and combine Web data dynamically  enable software to be delivered as continuous streams of services as opposed to packaged products. Web Services as a new Concept for enterprise application integration Web Services as a new Concept for enterprise application integration  The integration of data, information, knowledge; processes; applications; and business Web Services as a Web programming technology Web Services as a Web programming technology  today: Remote Procedure Calls (RPC) over HTTP, powered by WSDL, UDDI, SOAP, BPEL etc.  Tomorrow: location-independent distributed computational model, powered by three tier distributed service computing architecture

Take Home Message: Research and Standardization should focus on methodology and technologies that encourage and enable the use of semantics to increase the productivity of both the developers and the users of Web services and applications

The Web Services Stack (state of Art) Protocols ( Communication& Representation ) Description (What and How) Discovery ( Location and binding) TCP/IP HTTP/SMTP/BEEP XML SOAP/XMLP SOAP Blocks XML WSDL WSDL Extensions Process Agreements Inspection Registry (UDDI) Courtesy of James Snell “Transactional

WS as Software Architecture A distributed Service Computing Architecture A distributed Service Computing Architecture  Web Services connect computers and devices with each other through the Web infrastructure and exchange and combine Web data dynamically  Web Services enable on-the-fly software creation through the use of loosely coupled, reusable software components.  Web Services enable software to be delivered as continuous streams of services.

WS as Software Architecture “Web services are a new breed of Web application. They are self-contained, self-describing, modular applications that can be published, located, and invoked across the Web. Web services perform functions, which can be anything from simple requests to complicated business processes. … Once a Web service is deployed, other applications (and other Web services) can discover and invoke the deployed service.” IBM web service tutorial

Service-oriented Architecture  a model to depict Web services interactions, comprising relationships among three entities: A Web service provider; A Web service requestor; and a A Web service broker.  a generic model describing service collaboration, not specific to individual Web services. See ibm.com/developerworks/webservi ces/ WS as Software Architecture (today) Service provider Service broker Service requestor Find Bind Publish (Courtesy of IBM Corporation)

Network of Web Services: Security, Reliability QoS, Trust, Billing Service providers Service requestors [XML and Web Services Unleashed by Ron Schmelzer et.al] WS as Software Architecture (tomorrow) Web services networks act as intermediaries in Web services interactions

a New Concept for Enterprise Application Integration WS as a New Concept for Enterprise Application Integration Enterprise Application Integration Enterprise Application Integration  The integration of data, information, knowledge; processes; applications; and business  State of Art: emerging as  State of Art: emerging as a major share of the overall spent IT expenses > 30% of all IT budgets  > a trillion dollar per year world wide > 30% of all IT budgets  > a trillion dollar per year world wide  State of Art:  State of Art: many companies trying to solve their integration needs by adhoc integration projects do not scale, need Silver bullet to solve the growing problem, serious investment of dollars and time  Challenge: Goal-driven (structure efforts in the context of business processes) Goal-driven (structure efforts in the context of business processes) Extensible (extension in response to changed or new business needs) Extensible (extension in response to changed or new business needs) Reusable (create a vendor and platform independent software integration platform) Reusable (create a vendor and platform independent software integration platform)

WS as a New Programming Technology State of the art State of the art  Web Services are Remote Procedure Calls (RPC) over HTTP Key Components:  WSDL defines services as collections of network endpoints or ports. A port is defined by associating a network address with a binding; a collection of ports define a service.  SOAP is a message layout specification that defines a uniform way of passing XML-encoded data, a technology to allow for “RPC over the web”.  UDDI provides a mechanism for clients to find web services, in some way similar to ‘a DNS service’ for business applications.  BPEL4WS (BPEL) - Business process language to orchestrate interactions between Web services. (IBM, Microsoft, BEA, SAP, etc.)

Semantic Web Services Vision  Transform the Web from a static collection of information into a distributed device of computation, making content within the WWW machine-processable and machine- interpretable. A Conceptual modeling framework + associated conceptual architecture

Semantic Web Services "Semantic differences, remain the primary roadblock to smooth application integration, one which Web Services alone won't overcome. Until someone finds a way for applications to understand each other, the effect of Web services technology will be fairly limited. When I pass customer data across [the Web] in a certain format using a Web Services interface, the receiving program has to know what that format is. You have to agree on what the business objects look like. And no one has come up with a feasible way to work that out yet -- not Oracle, and not its competitors..." --- Oracle Chairman and CEO Larry Ellison