I'm not aware of available C# sample code for CMX API.
We have the Python and Node.js Sample Notification Listeners at https://cmxlocationsandbox.cisco.com/apidocs/code
Let's ask the community for help on this.
Thanks Matt - I have a customer that needs this pretty quickly, how do we reach the community to ask them or is this discussion the way to do it?
I saw Christian's reply regarding C# Sample code and will post it here as well.
Thanks for the question,
Not tested, but sounds like a good starting point:
You need to create a web socket (i.e. an open network port). Use the right network library for the operating system etc.
CMX will do a POST of the JSON or XML.
The node.js example in the documentation should help you to figure out the rest.