Transcript What is 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!
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)
Mobile Environment/Thin
Client
Performance
Web Services
CORBA
Web Services
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-