webthing / webthing
A PHP Web Thing Server implementation.
Requires
- cboden/ratchet: ^0.4.1
- justinrainbow/json-schema: ^5.2.9
- malik/crimson: ^1.0.0
- myclabs/deep-copy: ^1.9.4
- ramsey/uuid: ^3.9.2
- react/http: ^0.8.5
This package is auto-updated.
Last update: 2024-04-30 00:39:12 UTC
README
Implementation of an HTTP Web Thing. This library is compatible with PHP 7.4+.
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.
- Setting this property via a
-
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.
$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