Web Services

Web Services are SOA enablers of choice. A web service is software designed to support interoperable machine-to-machine interaction over a network. Software applications written in the various programming languages and running on various platforms can use web services to exchange data over computer network like the internet in a manner similar to inter process communication on a single computer. This interoperability (e.g. between Java and python or windows and Linux application) due to the use of open standards. OASIS and W3C are the primary committees responsible for the architecture and standardization of web services. Web Services have an interface that is described in a machine-processable format like WSDL.

XML Web Services is a way to expose .Net classes across a TCP/IP network. It
uses a combination of SOAP, HTTP and XML, and is exposed via a web site
containing the services. The services are accessed via SOAP requests. It
enables the developer to create classes that can be used via web browser or
any other HTTP client application across the Internet. For a simple example,
you could create an XML Web Service Method that returns a .Net DataSet to
the client. The client could call the method, passing the various parameters
it takes, and get back a result set of data from over the Internet

What is WSDL?

The Web Services Description Language (WSDL) is an XML format published for describing Web Services. It is commonly abbreviated as WSDL in technical literature & often pronounced as “Whiz-Dull”. WSDL describes the public interface to the Web services. This is an XML based service description on how to communicate using the web service; namely the protocol bindings and message formats required to interact with web services listed in the directory. The supported operations and messages are described abstractly and then bound to a concrete network protocol and message format.

WSDL is often used in combination with SOAP and XML Schema to provide web service over the internet. A Client (program) connecting to a web service can read WSDL to determine what functions are available on the server. Any special data types used are embedded in the WSDL file in the XML Schema. The Client can then use SOAP to actually call one of the functions listed in WSDL.

What is UDDI?

UDDI is a acronym for Universal Description , Discovery and Integration - platform –independent , XML-based registry for business worldwide to list themselves on the Internet. UDDI is an open industry initiative enabling business to discover each other and define how they interact over the internet. A UDDI business registration consists of three components:

1. White Pages – Address , contact and known identifiers;
2. Yellow Pages – industrial categorizations based on standard taxonomies ; and
3. Green Pages – technical information about services exposed by the business.

UDDI is nominally one of the core Web Services standards It is designed to be interrogated by SOAP messages and provide access to WSDL documents describing the protocol bindings and message formats required to interact with web services listed in its directory.

Seminar on Web Services:

Content:

Section 1:
Look Back,Whats wrong in previous Distributed models like DCOM,CORBA,RPC,RMI

Section 2:
Introduction,Defination,Example,Need for web services,Benefits, Key Features,Challenges faced By WS
Section 3:
SOAP,SOAP-XML Messaging Protocol,HTTP,XML,SOAP Header,WSDL,WSDL Elements ,WSDL header,UDDI,UDDI Components,

Section 4:
WebServices Platform,Web Services Security

Section 5:
WS for Java Developers,WS for .Net Developers

Section 6:
Web Services Application

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The term Web services describes a standardized way of integrating Web-based applications using the XML, SOAP, WSDL and UDDI open standards over an Internet protocol backbone. XML is used to tag the data, SOAP is used to transfer the data, WSDL is used for describing the services available and UDDI is used for listing what services are available. Used primarily as a means for businesses to communicate with each other and with clients, Web services allow organizations to communicate data without intimate knowledge of each other's IT systems behind the firewall.
Unlike traditional client/server models, such as a Web server/Web page system, Web services do not provide the user with a GUI. Web services instead share business logic, data and processes through a programmatic interface across a network. The applications interface, not the users. Developers can then add the Web service to a GUI (such as a Web page or an executable program) to offer specific functionality to users.
Web services allow different applications from different sources to communicate with each other without time-consuming custom coding, and because all communication is in XML, Web services are not tied to any one operating system or programming language. For example, Java can talk with Perl, Windows applications can talk with UNIX applications.
Web services do not require the use of browsers or HTML.
Web services are sometimes called application services.