How to pass empty value in a field for soap request

If the field is optional, you can simply leave it out, or just pass an empty sting

/Nenad
http://eviware.com

If i leave the filed empty it sends a null value in the request, i just want an empty value to be sent in the request.

for example it sends the request as username=null; and my requirement is username=; i have tried keeping all these things "", " ",emptyspace etc but nothing worked out for me

can any one suggest how to achieve this.