Canceling a HTTP request

Hi,
I'm new to HTTP and I have a basic question. 
My HTTP client will issue GET and POST requests to a HTTP 1.1 server. There
is a requirement from the caller to be able to cancel both GET and POST. My
understanding is that the only way to cancel the transaction is to close the
socket before the transaction completes. Is that correct? Will the server
automatically discard the data (in case of POST) when this is done?

Thanks,
Charu.