async vim with channel

client.vim

function! s:Handler(handle, msg)
    echom a:handle
    echom a:msg
endfunction

let handle = ch_open('localhost:8000', {'mode': 'json'})
call ch_sendexpr(handle, 'hello', function('s:Handler'))

server.js

var net = require('net');
net.createServer(function(socket){
    socket.on('data', function(data){
        var request = JSON.parse(data);
        console.log('received', request);
        setTimeout(function () {
            var response = [
                request[0],
                request[1]
            ];
            console.log('sending', response);
            socket.write(JSON.stringify(response));
        }, 2000);
    });
}).listen(8000);