can httpclient be used to invoke a webservice ?
Yes.
what is the need for having an httpclient, i could direclty call a webservice .. am i correct ?
If by "direct" you mean from within some Java client code, then you're correct. Most (probably all)
SOAP stacks have a tool that can generate Java client code to access a WS; generally it works by looking at the WSDL of the target WS. That generated client code would be much easier to work with than to use HttpClient. (The tool that ships with Axis is called "wsdl2java".)