File upload to restful service from GWT Entry point class (Not from server)

Following is my use case:

-Client tries to upload file through my website (developed using GXT) -I got the path at client side -Want to invoke direct call to restful webservice to upload file

Ultimately i have to upload file to a serv开发者_如何转开发er where webservice is exposed/deployed. I dont want to upload file first to a server where GWT project is deployed and then i will start uploading file to a server where webservice is running.

How to achieve this.