Similarly, we wrote a ProtoBufs encoder to communicate from LabVIEW RT to a .NET application and an Android device. This was for an internal demo (engineering version here, marketing version here).
In this case, LabVIEW natives are used to encode according to the Base 128 Varint and messaging structure in the link above.
It worked really well for our application-- pretty powerful and not very difficult. Feel free to send me a message for more information.