Looking for a .NET COMET server solution available for use with non-browser-based clients

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.NET

I have been asked to implement a COMET server app that will be able to communicate with our customer's JAVA client app using standard COMET server "push" messaging (the client app will send an http request to our server and our server app will need to hold the connection open in order to "push" data to the client app). The customer has requested that the data received be formatted in a specific manner (not using JSON). We also need to be able to convert the data being sent to the client to big endian byte order prior to being sent.

I would like to implement the server app in .NET, but am having difficulty finding a .NET COMET server/library solution that will work for our needs. I've looked at most of the previously suggested .NET COMET solutions, but most of these either appear to be developed specifically for browser-based clients (using javascript) or else appear to be limited in the format of the data that the server can push to the client (WebSync).

Are suggestions?