Getting sensors, data and actuators to work for ONE usecase has always been easy. just use what you need. The problem is still how you get these different comp

Getting sensors, data and actuators to work for ONE usecase has always been easy. just use what you need. The problem is still how you get these different company systems (silos) to cooperate. "how can you securely give the inside temperature from your alarm's smoke detector and feed it to the heating system to act upon". These services are provided from two different IoT companies. Here XMPP is the simple and perfect match. Any device in any company can talk to any other device in any other company just as easy as you send email to some one you know in another company. These companies can solve and hide there internal legacy systems with x500,modbus,coap, binary junk or whatever they need but when you pass the company xmpp server you pack it in a nice letter for others to easily understand what you are saying. With encryption and certificates. And you don't talk to servers/endpoints you don't do business with. How can NEST homes talk to openHAB? Zigbee legacy with new coap things? And how can they all participate in a smart city ?