Using Tessel CLI as a Node library for USB message passing

device.js

// Any copyright is dedicated to the Public Domain.
// http://creativecommons.org/publicdomain/zero/1.0/

process.on('message', function(msg) {
  console.log('reply');
  process.send(msg);
});

process.ref();

host.js

// Any copyright is dedicated to the Public Domain.
// http://creativecommons.org/publicdomain/zero/1.0/

var tessel = require('tessel');

var script =  '/device.js';

tessel.findTessel(null, true, function(err, client) {
    if (err) throw err;
    client.run(__dirname + script, ['tessel', script], {
          single: true,
        }, function () {
          client.stdout.resume();
          client.stdout.pipe(process.stdout);
          client.stderr.resume();
          client.stderr.pipe(process.stderr);
          console.info('Running script...');

          var count = 0;

          setInterval(function(){
            console.log('ping')
            client.interface.writeProcessMessage({count:count++, data: {foo: 'bar'}})
            client.once('message', function (m) {
              console.log('pong', m.count);
            });
          }, 1000);

          // Stop on Ctrl+C.
          process.on('SIGINT', function() {
            setTimeout(function () {
              logs.info('Script aborted');
              process.exit(131);
            }, 200);
            client.stop();
          });

          client.once('script-stop', function (code) {
            client.close(function () {
              process.exit(code);
            });
          });
    });
});