Overview of Web Services

1. Overview of Web Services ECE1770 Expert Topic Assignment Fan Chen Alvin Mok

2. Outline • What are Web Services & How Web Services Emerge • Web Services Architecture&Operations • Web Services Core Protocols • Some Issues • Web Services and other Middleware Platforms • Introduction to Microsoft .NET

3. What are “Web Services”? • Web Services are evolving, middleware platform that facilitate program-to-program interactions. • A service is a software entity that can be discovered and invoked by other software systems. • Definition from standardization body W3C • A Web service is a software system identified by a URI, whose public interfaces and bindings are defined and described using XML. Its definition can be discovered by other software systems.These systems may then interact with the Web service in a manner prescribed by its definition, using XML based messages conveyed by internet protocols

4. How “Web Services” Emerge • Web-based Applications Exploiting • E-Business Urging the program-to-program interactions and and integration across heterogeneous platforms • It came to the market at the time when demand for such technology was growing rapidly • The existing middleware technologies were not implemented with the Web in mind • It is backed by many key organizations (both commercial and non-commercial)

5. Web Services Standardization Bodies • W3C:World Wide Web Consortium • the most notable web organization founded in 1994 by the inventor of the web • Web Architecture, Document formats, interaction, etc • OASIS: Organization of Structured Information Standards • Drives the development, convergence and adoption of e-business standards • Service register and publish, Security, Transaction,etc • WS-I: Web Services Interoperation Organization • Initiated by IBM, Microsoft and other vendors • Articulate/promote a common Web Services vision • Integrate specifications from various standards bodies

6. Web Services Basic Architecture • Web services are consistent with established Service-Oriented Architecture(SOA) principles. • Web Services Component • Service • Service Description • Web services Roles • Service providers. • Service brokers • Service requestors. • Web Services Operations • Publish • Find • Interact

7. The Conceptual Web Service Stacks • Format: XML,Extensible Markup Language, to define structures of documents • Search and Find: UDDI • Universal Discovery Description and Integration, for registries of Web services • Description: WSDL • Web Services Description Language, to describe networked XML-based services • Messaging: SOAP • Simple Object Access Protocol, to define a uniform way of passing XML-encoded data. • Transport: Internet Protocol,HTTP, STMP, etc.

8. Operations and Message Flow

9. Some Issues • Technology Areas to be Standardized • Security: Inter-enterprise communications secure (XKMS, XACML,etc) • Business Process Management (WSFL) • Quality of Service and Reliable Messaging • System&Network Management • Chaos: There are tons of proposals from vendors but none of them has been universally accepted. • Different implementation for core protocols: Commercial and open-source toolkits vary widely. A long way to go before web services cover the full range of requirements for e-business!

10. Web Services and Other Middleware Platforms-A Vision or Over-simplification?- No one-size-fits-all solution!

11. Applicability-Examples

12. Web Services and CORBA-A Possible Integration Scenario- • SOAP request Generated • Gateway maps WSDL to IDL, builds COBRA request and send to the server • SOAP response is build out of the COBRA response

13. Web Services and Java • Java community sees XML as complementary • Java for algorithms, communications • XML as a universal data interchange format • Java API for XML:JAXP, JAX-RPC, JAXM, JAXR • J2EE + Web Services Developer Pack • Only for interoperation outside Java world • JMS, RMI, RMI/IIOP between Java applications

14. -Thank You-