use websockets

var WebSocket = require('ws');
var ws = new WebSocket('wss://n.block.io/');

ws.on('open', function open() {

  ws.on('message', function(data, flags) {
    // all messages filtered here. 
    console.log('data:    ', data)
    console.log('flags:    ', flags)

    // flags.binary will be set if a binary data is received.
    // flags.masked will be set if the data was masked.
  });


  function setWatch(address){
    console.log
    ws.send(JSON.stringify({
      "network": "BTC",
      "type": "address",
      "address": address
      }));
    };

  setWatch('xxx');

});

http://luketopia.net/2013/07/28/raspberry-pi-gpio-via-the-shell/