Caucho's Hessian binary protocol has been ported for .NET.
HessianC# (www.hessiancsharp.org) represents the latest implementation
of Caucho's Hessian Binary Web Service Protocol.
Hessian is a lightweight, self-describing binary RPC protocol. Hessian is a lightweight alternative to the XML-based web services protocols.
The Hessian makes web services usable without requiring a large framework. Because it is a binary protocol, it is well-suited to sending binary data without any need to extend the protocol with attachments. The Hessian protocol eliminates external API descriptions like WSDL.
HessianC# is also available for Compact Framework. It supports IIS. It is powerful and easy to use.