Receiving JSON data into my Web Service

Receiving JSON data into my Web Service

I'm hoping this will be a quick answer (probably a 'No').
I have set up a web service on Server B to receive HTTP POST data in JSON
format from Server A. I don't have code level access to Server A, but I
can manually trigger it to send data to my web service.
My current problem is that I have asked the Server A guys to send me a
sample of what is being sent so I can program for the formats etc, but
they are taking their sweet time responding.
I know the sending is working, and my WS is responding with my default
return string (though Server A is seeing it as an error rather than
success .. I don't know what they are expecting back for a successful
transmission yet).
I am wondering if it is possible to receive and analyse the data without
knowing exactly what is being sent? This way I can start my next phase of
coding without needing to wait for them to provide a sample. Plus, I'm not
sure how much the format will change for different jobs, so would be good
to be able to accept whatever is sent and be able to look at it.