> On 29 Aug 2017, at 10:44, Edward Welbourne <edward.welbou...@qt.io> wrote: > > Thiago: >>> If you're going to communicate with a tiny MCU connected over a mesh >>> network like 6LoWPAN/Thread, you won't be using TCP. Much less HTTP. > > and you'll want that MCU running something light-weight in C++, not a > web-bloat thing. So Qt is just the thing for the job.
A tiny MCU means an Atmel with a couple kilobytes of RAM. Or maybe an ESP8266, the canonical IOT device right now if you want to use TCP/IP (WiFi) (rather than some lower-powered network like BLE, Zigbee, Z-Wave or LoRa); that has oodles more power and memory, but still a few orders of magnitude less than you need for Linux + Qt. I ran into the RAM shortage while hacking on this firmware (trying to add a few features): https://github.com/radhoo/uradmonitor_kit1 It has enough memory to allocate ONE TCP packet: a 600 byte global static, plus a few more global variables, and reserve some space for the stack. And yet it has a web server for serving up either a human-readable page or JSON on demand, and it also pushes data to a central server periodically. I’d like to make it discoverable via Bonjour but that might be pushing it. After reading about CoAP I think it would be a much better fit than HTTP for such a device, so I hope I find the time to try. But then again, browsers don’t have CoAP yet, so I wonder if there could be a web client that uses JS to talk to it. Having to build a dedicated Qt client for it would be a step backwards in a way, but also nice for a desktop widget or some such. Qt for IoT is maybe primarily for devices that have graphically-rich screens. But they can be clients reading data from truly-embedded sensors, and they might also have data of their own to serve to other clients (consolidated results, or just extra sensors that happen to be attached). There are some PLCs powerful enough to run Linux, though, like these: https://www.bachmann.info/en/products/controller-system/ Some industrial applications can afford to use them, and so can the shipping industry, as I learned a couple of years ago on a certain consulting gig… and so they can afford to use Qt too, just for network comms, even though there is no GUI. _______________________________________________ Development mailing list Development@qt-project.org http://lists.qt-project.org/mailman/listinfo/development
