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

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

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

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)

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

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

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.

Operations and Message Flow

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!

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

Applicability-Examples Web Interface Web Services Secure Architecture with Firewall Legacy Component( other CORBA EJB) CORBA Mobile Environment/Thin Client Performance

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

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

-Thank You-