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 Interface Web Services

Secure Architecture with Firewall

Web Services

Legacy Component( other CORBA EJB)

CORBA

Mobile Environment/Thin Client

Web Services

Performance CORBA

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-