Say I have a service exposing two end points, 1st is a NetTCPBinding the second is any flavour of HttpBinding. They both implement exactly the same service contract.
What is the difference in what is sent on the wire?
I think that in all cases, before the message is put onto the wire it will be converted to binary so, also http sits on top of tcp in networking terms - so somewhere extra is needed for http communications.
Appreciate the question is a bit vague but hopefully someone will know what I am trying to ask :)
In WCF a particular binding does not necessarily imply a particular encoding. Various bindings can be configured to use various encodings. Net.TCP uses a binary encoding by default (MTOM I think), and HTTP uses a text/xml encoding by default.
With net.tcp your messages go sender -> net.tcp -> receiver. With HTTP they go from sender -> http -> tcp -> http -> receiver. There's an extra layer. The advantage of tcp is both of those: Both the extra layer and the default encoding.
HTTP with a binary encoding approaches net.tcp performance.
EDIT: Actually I think there may also be other optimizations in Net.TCP. It's a WCF-WCF communication scenario, so MS has control of both ends.