Hello,
I’d like to share with you some ideas along with some practical implementations
of Ubuntu Snappy Core Frameworks for developing IoT apps as set of abstractions
to provide access to standard things like simple hardware interfaces (GPIO,
UART, I2C), wireless protocols (Bluetooth Low Energy, ZigBee, EnOcean), cloud
services, devices connected via this interfaces etc. With all of that
architects and developers will be able to mash up various APIs on edge devices,
bridge local protocols and peripherals into the cloud, or run event based logic
on edge device.
Imagine the task when you need to connect a Bluetooth Low Energy (BLE) switch
to control a BLE light bulb and at the same time, have the ability to turn
lights on or off remotely, through a web app. Without frameworks you will have
to rely on language/platform specific libraries to work with BLE, and cloud
platform and carry these dependencies with your snaps, compile low-level
libraries for different architectures increasing overall complexity of the
solution. That’s how things are currently done with OpenWRT, Raspbian,
BeagleBone, etc.
Having these Frameworks and Ubuntu Snappy Core you will have to: install BLE
framework snap, add BLE Bulb and Switch profile Framework Snaps, then you will
have to write app code like:
def toggle():
bulb = dbus.SystemBus().get_object("com.devicehive.ble.bulb",
"com/devicehive/ble/bulb")
mac = bulb.scan()
if mac:
bulb.toggle(mac)
DBusGMainLoop(set_as_default=True)
sw = dbus.SystemBus().get_object("com.devicehive.ble.switch",
"com/devicehive/ble/switch")
mac = sw.scan()
sw.connect_to_signal(mac, "clicked", toggle)
GObject.MainLoop().run()
We are taking Python as a meta-language, but same concepts, can be applied to
Go, Node.js, C++, or even shell script.
Now developer can publish a Snap into Ubuntu Snappy store for further use. As
you can see we suggest to use dbus as interface for frameworks making it the
only dependency. Lots of programming languages already have dbus bindings, some
of them, with dynamic typing like Python or Node.js, can provide syntax of
converting method calls into d-bus calls.
Another example, more low-level, might be connecting simple hardware chips.
Dallas DS18B20 for example. It has 1-wire protocol and each developer who want
to use it can start do in a few sec with such frameworks. Just install 1-wire
framework(1-wire interface implementation) and ds18b20 framework (chip protocol
implementation for 1-wire interface) and the to find out a temperature just
call:
sensor = dbus.SystemBus().get_object("com.devicehive.1wire.ds18b20",
"com/devicehive/1wire/ds18b20")
sensor.get_temperature()
As it can be seen from examples above, instead of carrying over dependencies,
Frameworks can be installed through standard snappy deployment mechanism and
provide the same developer experience of hardware and cloud abstraction across
different languages and different SoCs.
I think it's possible to imagine plenty of other usages. More detailed
description of idea you can find here:
https://docs.google.com/a/devicehive.com/document/d/1XxXMZx5ff8x05p92zdly8Av7LhWKQwywUdLG4v83-zc/edit?usp=sharing
To prove the idea, I've implemented simple GPIO framework. It works on real
hardware - http://youtu.be/4RsMiQU_LMM
code of framework is here:
https://github.com/devicehive/IoT-framework-gpio/blob/master/src/daemon/gpio-daemon
code of examples:
https://github.com/devicehive/IoT-framework-gpio/tree/master/src/examples
dbus specification:
https://github.com/devicehive/IoT-framework-gpio/blob/master/DBUS-SPEC.md
You can also download prebuilt snaps for it and play:
framework snap:
https://drive.google.com/a/devicehive.com/file/d/0B9jKFl3qYG3paFVzekR6bzhYamc/view?usp=sharing
examples snap:
https://drive.google.com/a/devicehive.com/file/d/0B9jKFl3qYG3pdXBDOUd3Nm5ycjQ/view?usp=sharing
Currently to run it on Ubuntu Snappy you need to modify /etc/dbus-1/system.conf
- change 'deny' to 'allow' in this two lines
<deny own=*" />
<deny send_type="method_call" />
Another quick example is building s Snap that relies on BLE and EnOcean
Frameworks to control a BLE bulb with a wireless switch without any battery
power, generating energy to transmit signals through mechanical force:
http://www.youtube.com/watch?v=S-sbMeetzL0
Provided there are EnOcean and BLE frameworks, the code looks like this and can
be transferred across different platforms and re-created in different languages
having only dbus binding as a dependency.
==================================
#!/usr/bin/python3
import dbus
from dbus.mainloop.glib import DBusGMainLoop
from gi.repository import GObject
import json
DBUS_BUS_ENOCEAN_NAME = 'com.devicehive.enocean'
DBUS_BUS_BLE_NAME = 'com.devicehive.bluetooth'
SWITCH_ADDRESS = '00:2A:1A:B8'
BULB_ADDRESS = 'F4:04:4C:0C:58:A3'
bulb_on_value = '0f0d0300ffffffc800c800c8000059ffff'
bulb_off_value = '0f0d0300ffffff0000c800c8000091ffff'
bulb_handle = 0x002b
DBusGMainLoop(set_as_default=True)
def init_bulb():
bus = dbus.SystemBus()
ble_manager = bus.get_object(DBUS_BUS_BLE_NAME, '/')
bulb_path = ble_manager.Create(BULB_ADDRESS,
dbus_interface='com.devicehive.BluetoothManager')
return bus.get_object(DBUS_BUS_BLE_NAME, bulb_path)
bulb = init_bulb()
def turn_bulb(on):
if on:
print('ON')
bulb.Write(bulb_handle, bulb_on_value, False,
dbus_interface='com.devicehive.BluetoothDevice')
else:
print('OFF')
bulb.Write(bulb_handle, bulb_off_value, False,
dbus_interface='com.devicehive.BluetoothDevice')
def message_received(value):
res = json.loads(value)
if res['sender'] == SWITCH_ADDRESS:
if res['R1']['raw_value'] == 2:
turn_bulb(True)
if res['R1']['raw_value'] == 3:
turn_bulb(False)
def main():
bus = dbus.SystemBus()
enocean_manager = bus.get_object(DBUS_BUS_ENOCEAN_NAME,
'/com/devicehive/enocean')
enocean = dbus.Interface(enocean_manager, DBUS_BUS_ENOCEAN_NAME)
enocean.connect_to_signal('message_received', message_received)
try:
GObject.MainLoop().run()
except KeyboardInterrupt:
pass
if __name__ == '__main__':
main()
==================================
Thanks,
Nikolay Khabarov
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