am new to wsdl,xsd,xls. i read all these 3 topics. but still can anyone tell me what is it used for in layman terms.
a.are these kind of contracts which should be satisfied while message is sent from ep1 to ep2?
b.are these 3 files generated using automated tool or we have to write it from scratch
c.for example if i am going to send one xml file as message from ep1 to ep2, how many wsdl,xsd and xsl files required.
A WSDL is sort of an API that a SOAP WS fulfills. It contains all the information you would need to write a client for a WS.
An XSD (a.k.a. XML Schema) describes the structure of a particular XML document - which elements are mandatory, which can be omitted, which values need to have which datatypes. It's generally used in WSDLs to describe the content of a SOAP message.
Not sure what "xls" would have to do with it. I'm guessing that you may mean XSL -which is at least XML-related- but even then I don't see the connection to WS.
The easiest way -IMO- to create a WS is to write the Java class that implements it. The tools of your SOAP engine can then be used to create the WSDL (and XSD) from that.