I woulbe sending and receiving .wsdl file format. Though the .wsdl is the wrapper around of XML, the file extension is varying from the .XML.
A WSDL file is a description of a web service, not a device to send anything, or a wrapper around anything. The only places where I could see the value of transferring WSDLs around would be very unlikely to involve a Flex GUI. Can you provide some more detail of what you're trying to do?
Should I convert .wsdl into .xml
WSDL *is* XML - there's nothing to convert. But then -see above- I don't understand what you mean by "sending and receiving .wsdl file format".