DownloadWeb Things PHP
Implementation of an HTTP Web Thing. This library is compatible with PHP 7.1+.
Installation
The `webthing can be installed using composer ` via the following command:
composer require webthing/webthing:^0.0.1
Running the Example
The following list of commands clones this repository and installs all dependencies using the composer and runs the single-thing.php example. git clone https://github.com/maliknaik16/webthing-php.git
cd webthing-php
composer install
php examples/single-thing.php
Example Implementation
In 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:
$light = new Thing(
'urn:dev:ops:my-lamp-1234',
'My Lamp',
['OnOffSwitch', 'Light'],
'A web connected 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.
$light->addProperty(new Property(
$light,
'on',
new Value(TRUE, function($v) {
echo "On-State is now " . $v . "\n";
}),
[
'@type' => 'OnOffProperty',
'title' => 'On/Off',
'type' => 'boolean',
'description' => 'Whether the lamp is turned 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.
$light->addProperty(new Property(
$light,
'brightness',
new Value(50, function($v) {
echo "Brightness is now " . $v . "\n";
}),
[
'@type' => 'BrightnessProperty',
'title' => 'Brightness',
'type' => 'integer',
'description' => 'The level of light from 0-100',
'minimum' => 0,
'maximum' => 100,
'unit' => 'percent',
])
);
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.
$server = new WebThingServer(new SingleThing($thing), '127.0.0.1', 8888, 8081);
$server->start();
$server->startWebSocket();
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:
$sensor = new Thing(
'urn:dev:ops:my-humidity-sensor-1234',
'My Humidity Sensor',
['MultiLevelSensor'],
'A web connected humidity sensor'
);
Then we create and add the appropriate property:
- `level `: tells us what the sensor is actually reading
- Contrary 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.
```php
$level = new Value(0.0);
$sensor->addProperty(new Property(
$sensor,
'level',
$level,
[
'@type' => 'LevelProperty',
'title' => 'Humidity',
'type' => 'number',
'description' => 'The current humidity in %',
'minimum' => 0,
'maximum' => 100,
'unit' => 'percent',
'readOnly' => TRUE,
])
);
```
Now 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.
// $level is a `Value` object.
// $loop is a `React\EventLoop\Factory` object.
$loop->addPeriodicTimer(7, function() use ($level) {
$new_level = readFromGpio();
printf("Setting new humidity level: %s\n", $new_level);
$level->notifyOfExternalUpdate($new_level);
});
function readFromGpio() {
return abs(70.0 rand() (-0.5 + rand()));
}
This will update our `Value object with the sensor readings via the $level->notifyOfExternalUpdate(readFromGpio()); call. The Value ` object now notifies the property and the thing that the value has changed, which in turn notifies all websocket listeners.
Resources
- https://iot.mozilla.org/wot
- https://iot.mozilla.org/framework/
- https://iot.mozilla.org/gateway/
- https://www.w3.org/WoT/IG/
License
Mozilla Public License Version 2.0
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