Package: aiowebthing
aiowebthingWhat isaiowebthing?aiowebthingis a library for the Web of Things protocol in Python Asyncio. This library is derived of webthing-python project (supporting Tornado) but adapted for Starlette (based on Uvicorn for better performance).additional featuresadditional_routes -- list of additional routes add to the serveradditional_middlewares -- list of additional middlewares add to the serveradditional_on_startup -- list of additional starup event handlers add to the serveradditional_on_shutdown -- list of additional shutdown event handlers add to the serverthing.sync_property -- Sync a property value from cloud or mqtt broker etc, property set value with no action disclaim.thing.property_action -- addional action sync the property change to device.property.set_value(value, with_action=True) -- if with_action is True, Value instance should emitupdate, elsesyncAdd the property change observer to notify the Thing about a property change or do some additional action:self.value.on("update",lambda_:self.thing.property_notify(self))self.value.on("sync",lambda_:self.thing.property_notify(self))self.value.on("update",lambda_:self.thing.property_action(self))Installationaiowebthing can be installed via pip, as such:$ pip install aiowebthingRunning the Sample$ wget https://raw.githubusercontent.com/hidaris/aiowebthing/master/example/test.py$ uvicorn test:app --reloadThis starts a server and lets you search for it from your gateway through mDNS. To add it to your gateway, navigate to the Things page in the gateway's UI and click the + icon at the bottom right. If both are on the same network, the example thing will automatically appear.Example ImplementationIn this code-walkthrough we will set up a dimmable light and a humidity sensor (both using fake data, of course). Both working examples can be found in here.Dimmable Light
Imagine you have a dimmable light that you want to expose via the web of things API. The light can be turned on/off and the brightness can be set from 0% to 100%. Besides the name, description, and type, a Light is required to expose two properties:on: the state of the light, whether it is turned on or off
Setting this property via a PUT {"on": true/false} call to the REST API toggles
the light.brightness: the brightness level of the light from 0-100%
Setting this property via a PUT call to the REST API sets the brightness level of this light.
First we create a new Thing:fromwebthingimportThing,Property,ValueclassLight(Thing):type=['OnOffSwitch','Light'],description='A web connected lamp'super().__init__('urn:dev:ops:my-lamp-1234','My Lamp',)Now we can add the required properties.The on property reports and sets the on/off state of the light. For this, we need to have a Value object which holds the actual state and also a method to turn the light on/off. For our purposes, we just want to log the new state if the light is switched on/off.asyncdefbuild(self):on=Property('on',Value(True,lambdav:print('On-State is now',v)),metadata={'@type':'OnOffProperty','title':'On/Off','type':'boolean','description':'Whether the lamp is turned on',})awaitself.add_property(on)The brightness property reports the brightness level of the light and sets the level. Like before, instead of actually setting the level of a light, we just log the level.brightness=Property('brightness',Value(50,lambdav:print('Brightness is now',v)),metadata={'@type':'BrightnessProperty','title':'Brightness','type':'number','description':'The level of light from 0-100','minimum':0,'maximum':100,'unit':'percent',})awaitself.add_property(brightness)Now we can add our newly created thing to the server and start it:# If adding more than one thing, use MultipleThings() with a name.# In the single thing case, the thing's name will be broadcast.withbackground_thread_loop()asloop:app=WebThingServer(loop,Light).create()This will start the server, making the light available via the WoT REST API and announcing it as a discoverable resource on your local network via mDNS.Sensor
Let's now also connect a humidity sensor to the server we set up for our light.A MultiLevelSensor (a sensor that returns a level instead of just on/off) has one required property (besides the name, type, and optional description): level. We want to monitor this property and get notified if the value changes.First we create a new Thing:fromwebthingimportThing,Property,ValueclassLight(Thing):type=['MultiLevelSensor'],description='A web connected humidity sensor'super().__init__('urn:dev:ops:my-humidity-sensor-1234','My Humidity Sensor',)Then we create and add the appropriate property:level: tells us what the sensor is actually readingContrary to the light, the value cannot be set via an API call, as it wouldn't make much sense, to SET what a sensor is reading. Therefore, we are creating a readOnly property.asyncdefbuild(self):awaitself.add_property(Property('level',Value(0.0),metadata={'@type':'LevelProperty','title':'Humidity','type':'number','description':'The current humidity in %','minimum':0,'maximum':100,'unit':'percent','readOnly':True,}))returnselfNow we have a sensor that constantly reports 0%. To make it usable, we need a thread or some kind of input when the sensor has a new reading available. For this purpose we start a thread that queries the physical sensor every few seconds. For our purposes, it just calls a fake method.self.sensor_update_task=\get_event_loop().create_task(self.update_level())asyncdefupdate_level(self):try:whileTrue:awaitsleep(3)new_level=self.read_from_gpio()logging.debug('setting new humidity level:%s',new_level)awaitself.level.notify_of_external_update(new_level)exceptCancelledError:passThis will update our Value object with the sensor readings via the self.level.notify_of_external_update(read_from_gpio()) call. The Value object now notifies the property and the thing that the value has changed, which in turn notifies all websocket listeners.