Web service Jargons

The following are the terminologies involved in the SOAP based web services

·         WSDL

·         UDDI

·         SOAP

1. Web service user (Client) access the UDDI and find out the web service WSDL for its need
2.  It acquires the WSDL from the UDDI to access the Web service
3. The client generates the necessary stubs to access the web service and call it using the SOAP message
4. The response is sent back to the client from the service end point after executing the service

WSDL:

                WSDL stands for Web Service Description Language. It’s a XML file. It contains the details of operations available in the web service. It includes service operation name, input parameters and return type.

Why do we need WSDL?

                In Java, we used to write an implementation class and share its details with the client using interface. Here the interface is act as a contract.  If the client wants to access the implementation class then they need to implement the interface. The interface provides the details like operation name, input arguments, return type and the exceptions if any.

                But clients consuming a web service are from different technologies. Your web service may consume by a .NET or C++ or Java client. So here your interface or contract to a service must be independent of any technologies. This is the reason for the WSDL which is primarily an XML file used as a contract.

UDDI:

UDDI stands for Universal Description, Discovery and Integration. It acts as a yellow page for a web service. It contains the details for various services and service provider details.

SOAP:

                SOAP stands for Simple Object Access Protocol which is used for accessing web services. This protocol used along with HTTP to transport XML messages between two applications. SOAP is based on XML so its language and platform independent. SOAP provides a way of communication between different applications running on different platforms (like WINDOWS, LINUX, SOLARIS) in different technologies (like .NET, JAVA, C++). 

SEI:

                SEI stands for service end point interface. The web service client may be a Java and the service may be implemented by a .NET. How does a Java client can send a Vector to a .NET web service? .NET web service doesn't know anything about a Java vector. So here we need a middle man to convert this Java vector to a language neutral format which is XML here. The same operation should be done in reverse in the service side.

                A Java vector needs to be converting into a XML or a language neutral format in the Java client side and same to be converting into .NET vector in the service side.

The service end point interfaces does this conversion.