Architecture: net.connect() and connection callbacks ...

I wanted to report back that your technique works well. What I think we want to do is put our heads together and capture and document the EXACT nature of the contract between the socketserver layer and the board layer. Specifically, each board must implement a set of expected functions. What we need to do is pin down exactly the nature of the contract including semantics. The code source code of the Espruino base and examining the examples describes the signatures of the functions ... but doesn't capture the execution flow nor semantics and I think (in hind sight) that is what gave me most of my grief. If we can learn from this and make notes on what each of the board supplied functions does and its expected contract ... that would help a lot.

I have found yet another blocking vs non-blocking issue which is going to be tricker to resolve ... and that is "gethostbyname" which takes as input a DNS name and returns the corresponding IP address. The ESP8266 has this ... it is called espconn_gethostbyname ... however ... it is asynchronous. What I mean by this is that its spec is that when one calls it, one supplies a callback function that will be called in the future when the DNS resolution is complete. In the network and serversocket code, we expect it to be blocking.