To improve on the existing HTTP "GET" based AJAX interface to MIDAS, I have been looking at other possible RPCs.

The JSON-RPC standard looks to be the most interesting and my experimental implementation now reached the point where other midas users are welcome to try it:

1. Please checkout the git branch "feature/json_rpc", build and run midas as per normal instructions.
2. Look at the MIDAS "Programs" page, you will "see double", the top is the normal midas programs page, the bottom is the new JSON-RPC based page that updates 
every 1 second.
3. Look at example.html page in examples/javascript1, run that experiment push the buttons.
4. Look at mhttpd.js functions mjsonrpc_xxx() to see how the RPC works.
5. Look at jsonrpc_user.cxx in .../src for examples of adding custom rpc functions to midas.

The main improvement is the use of HTTP POST request which allows unlimited data to be sent to midas (permitting proper implementation of ODB "paste" or "mset") 
and use of JSON encoding for all data, including error responses (removing previous ambiguity and poor documentability of some old AJAX functions).

Cross-origin AJAX requests continue to be fully supported (thanks to Bill Mills) - web pages loaded from local file or from some other web server can make AJAX 
requests into mhttpd. (this trivial functionality is normally prohibited by browser security).

My implementation follows these internet standards:

// https://tools.ietf.org/html/rfc4627 - JSON RFC
// http://www.jsonrpc.org/specification - specification of JSON-RPC 2.0
// http://www.simple-is-better.org/json-rpc/transport_http.html

With following variances:
- JSON encoding for NAN and Inf is Javascript-compatible strings "NaN", "Infinity" and "-Infinity"
- HTTP GET is not supported (not recommended by standard)
- batched JSON-RPC requests not supported yet

K.O.