README

Overview

Lightning is a PHP micro framework that lets you quickly connect, publish, and subscribe to MQTT topics.

<?php

require 'vendor/autoload.php';

$mqtt = new \Lightning\App();
$mqtt->subscribe('/hello/+name', 0, function ($response) {
    $topic = $response->getRoute();
    $name = $response->attr('name');
    $message = $response->getMessage();
});
$mqtt->listen();

$mqtt->close();

Features:

• PSR-4 compliant class loading
• Modular codebase for extensibility
• Topic router with inline variable support
• Wildcard support
• Lightweight MQTT Topic syntax checker

Installation

System Requirements

• PHP 5.6 or newer

How to Install Lightning

We recommend that you install Lightning with the Composer dependency manager, using:

composer require brandonhudson/lightning

Require the Composer autoloader into your PHP script, and you are ready to start using it.

<?php
require 'vendor/autoload.php';

Usage

Connection

In order to connect to an MQTT broker, you'll need to initialize a new Lightning\App object with the following parameters:

Example:

<?php

require 'vendor/autoload.php';

$host = 'mqtt.example.com';
$port = 1883;
$clientID = md5(uniqid());
$username = 'user';
$password = 'password';

// Without username/password
$mqtt = new \Lightning\App($host, $port, $clientID);

// With username/password
$mqtt = new \Lightning\App($host, $port, $clientID, $username, $password);

if (!$mqtt->connect()) {
    exit(1);
}

$mqtt->close();

Publishing

To publish with Lightning, you'll need to have a connection to your MQTT broker already established. Publishing to a topic includes the following parameters:

Example:

<?php

require 'vendor/autoload.php';

$host = 'mqtt.example.com';
$port = 1883;
$clientID = md5(uniqid());

$mqtt = new \Lightning\App($host, $port, $clientID);

if (!$mqtt->connect()) {
    exit(1);
}

$mqtt->publish("/hello/world", '{"hello":"world"}', 1);
$mqtt->close();

Subscribing

Overview

Lightning offers you a powerful way to quickly subcribe and react to messages sent on specific topics. Modeled after the Slim PHP Framework, Lightning subscriptions are designed in a callback pattern, where a function is invoked when a message is recieved on the subscribed topic.

Topics

Lightning supports topics that use the / seperator for logical components of the topic. Example:

/home/temperature/increase

While this does narrow the possibilities for how you can structure your topics, we do this to allow you to parse variables out of the topic after it has been subscribed to (see below).

Inline Variables

Lightning supports inline variable declaration right inside of the topic, allowing you to easily parse variables out of the response when a message is received. In order to declare a variable, you include the + operator along with the variable name (ex: +id) in between two forward slashes.

Example:

/users/+id/status

/building/+id/zone/+zoneID/temperature

As with standard variable naming conventions, inline variables need to have unique names within a single topic (you cannot reuse the same variable name twice in a single topic). If you misformat a route, Lightning will throw a Lightning\Exception\RouteException detailing the problem.

Wildcards

Lightning also supports wildcard topic delcarlation, allowing you to recieve messages on a topic that does not have a fixed topic structure. Per the MQTT specification, wildcards are only available at the end of the topic - you cannot include a wildcard in the middle of a topic. A wildcard is denoted using the # symbol. Example:

/users/#  //subscribe to anything that has /users/ at the beginning of the topic

#  //subscribe to everything

If you misuse a wildcard in your topic, Lightning will throw a Lightning\Exception\RouteException detailing the problem.

Mixed Uses

Lightning topics can include both inline variables and wildcards in a topic. Example:

/users/+id/#

Callbacks

Lightning uses callback methods to invoke code when a message is received for a specific topic. A callback can be defined inline as an anonymous function when you subscribe to a topic, or you can pass the string name function that should be invoked - any function that will return true to is_callable() will work.

The callback function takes one argument, $response, which is a Lightning\Response object (see below for more details on interacting with responses)

Implementation

To subscribe to a route with Lightning, you need to call the subscribe() function with the following parameters:

Example:

<?php

require 'vendor/autoload.php';

function exampleCallback(\Lightning\Response $response) {
    $message = $response->getMessage();
}

$host = 'mqtt.example.com';
$port = 1883;
$clientID = md5(uniqid());

$mqtt = new \Lightning\App($host, $port, $clientID);

if (!$mqtt->connect()) {
    exit(1);
}

// A callback defined inline at the time of subscribing
$mqtt->subscribe('/users/+id/status', 0, function (\Lightning\Response $response) {
    $message = $response->getMessage();
});

// A callback referencing another previously defined function
$mqtt->subscribe('/users/+id/status', 0, 'exampleCallback');

// Listen will poll for new messages sent to this client
$mqtt->listen();

Working with Responses

Lightning responses are modeled closely after PSR HTTP responses, including a number of useful methods for retrieving information about the message you receive.

Methods

Example

<?php
require 'vendor/autoload.php';

$host = 'mqtt.example.com';
$port = 1883;
$clientID = md5(uniqid());

$mqtt = new \Lightning\App($host, $port, $clientID);

if (!$mqtt->connect()) {
    exit(1);
}

// Example with inline variable
$mqtt->subscribe('/users/+id/status', 0, function (\Lightning\Response $response) {
    $message = $response->getMessage();
    $topic = $response->getRoute();
    $id = $response->attr('id'); // fetches the id attribute from the topic
});

// Example with wildcard
$mqtt->subscribe('/users/#', 0, function (\Lightning\Response $response) {
    $message = $response->getMessage();
    $topic = $response->getRoute();
    $wildcard = $response->getWildcard(); // fetches the id attribute from the topic
});

$mqtt->listen();

Contributing

If you find a problem with the Lightning implementation, please open an issue. Improvements and suggestions are welcome - feel free to open a pull request!

License

MIT License

Copyright (c) 2017 Brandon Hudson

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Based on the work of Andrew Milsted and the phpMQTT project