Presentation on theme: "Overview of Web Services Fan Chen Alvin Mok ECE1770 Expert Topic Assignment."— Presentation transcript:
Overview of Web Services Fan Chen Alvin Mok ECE1770 Expert Topic Assignment
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 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. Format: XML,Extensible Markup Language, to define structures of documents
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!
Web Services and Other Middleware Platforms -A Vision or Over-simplification?- No one-size-fits-all solution!
Applicability-Examples Web InterfaceWeb Services Secure Architecture with Firewall Web Services Legacy Component( other CORBA EJB) CORBA Mobile Environment/Thin Client Web Services PerformanceCORBA
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