How I (ab)used PHP with the help of ReactPHP

PHP is one of the most accessible and commonly used languages in computer programming. It’s used for building websites, web applications, micro services and loads of other stuff. Normally we would not use it to control hardware. But let that be the showcase of this talk. I’ll show you how I (ab)used PHP to control hardware used during track and field competitions. It involves LED-panels, serial-to-ethernet-­convertors and the use of reactphp, an event-driven non-blocking I/O library.

Transcript

1. how I (ab)used PHP
   with the help of reactphp
   

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2. Stijn Vannieuwenhuyse
   head of engineering at teamleader
   

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3. Stijn Vannieuwenhuyse
   track and field timer
   

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4. Track & Field
   it's all about precise numbers
   

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5. Team Arctic v.z.w.
   team for athletics' results communication, timing, information and coordination
   

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6. Track & Field
   it's all about precise numbers
   

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8. What's wrong with it?
   Why change?
   

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9. Problem 1
   How to integrate?
   

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10. FT01
    Long jump men
    
    
    
    Lambert Romain
    DAMP
    
    
    A6
    
    Rank: 1
    
    

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11. RS232
    

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13. Problem 2
    How to connect?
    

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14. PHP
    developer
    

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15. reactphp
    event-driven, non-blocking I/O with PHP
    

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16. public function run()
    {
    $this->running = true;
    while ($this->running) {
    $this->nextTickQueue->tick();
    $this->futureTickQueue->tick();
    $this->timers->tick();
    if (!$this->running || !$this->nextTickQueue->isEmpty() || !$this->futureTickQueue->isEmpty()) {
    $timeout = 0;
    } elseif ($scheduledAt = $this->timers->getFirst()) {
    $timeout = $scheduledAt - $this->timers->getTime();
    if ($timeout < 0) {
    $timeout = 0;
    } else {
    $timeout *= self::MICROSECONDS_PER_SECOND;
    }
    } elseif ($this->readStreams || $this->writeStreams) {
    $timeout = null;
    } else {
    break;
    }
    $this->waitForStreamActivity($timeout);
    }
    }
    

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17. composer require react/react
    

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18. Problem 2
    How to connect?
    

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19. $loop = LoopFactory::create();
    $connector = new TcpConnector($loop);
    $connector->create('192.168.1.93', 6000)->then(
    function(Stream $stream) {
    echo "connected", PHP_EOL;
    }
    );
    $loop->run();
    

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20. composer require react/socket-client
    

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21. Problem 3
    How to communicate?
    

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22. C\x0d
    

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23. TFF000000a2000700100030a012345678910\x0d
    

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24. TFF000000a2000700100030a012345678910\x0d
    TRRGGBBXXXXYYYYLLLLHHHHFDDDDDDDDDDDD\x0d
    T: command name
    RRGGBB: hex color value
    XXXX: x-position in hex, starting from left
    YYYY: y-position in hex, starting from top
    LLLL: length of the text in hex
    HHHH: heigth of the text in hex
    F: font-type
    D: data
    \x0d: end marker
    

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25. Domain Driven Design
    make the implicit explicit
    

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26. interface Instruction
    {
    /**
    * @return string
    */
    public function toData();
    }
    

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27. class Clear implements Instruction
    {
    public function toData()
    {
    return "C\x0d";
    }
    }
    

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28. class Text implements Instruction
    {
    private $data;
    private $x;
    private $y;
    private $height;
    private $length;
    private $colorCode;
    private $font;
    public function __construct($data, $x, $y, $height, $length, $colorCode, $font)
    {
    $this->data = $data;
    $this->x = $x;
    $this->y = $y;
    $this->height = $height;
    $this->length = $length;
    $this->colorCode = $colorCode;
    $this->font = $font;
    }
    public function toData()
    {
    return sprintf(
    "T%s%04X%04X%04X%04X%s%s\x0d",
    $this->getColor(), //returns hex string of red, green or yellow
    $this->x,
    $this->y,
    $this->length,
    $this->height,
    $this->font,
    $this->data
    );
    }
    }
    

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29. B00100028004700af0f0f0f0fff0fff0f\x0d
    

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30. BXXXXYYYYLLLLHHHHDDDDDDDDDDD\x0d
    B: command name
    XXXX: x-position in hex, starting from left
    YYYY: y-position in hex, starting from top
    LLLL: length of the text in hex
    HHHH: heigth of the text in hex
    D: data
    \x0d: end marker
    

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31. Domain Specific Language
    

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32. . . . . . . . . . . . Y Y Y Y Y Y Y . . . . . . . . . . . . . . . . . . . Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y
    R R R R R R R R R R R Y . . . . . Y G G G G G G G G G G G G G G G G G G . Y . . . . . . . . . . . . . . . . . . . . . . . . . .
    . . . . . R . . . . . Y . Y Y Y . Y . . . . . G . . . . . G . . . . . G . Y . . . . . . . . . . . . . . . . . . . . . . . . . .
    . . R . . R . R R R . Y . . . Y . Y . G . G . G . G G G . G . G G G . G . Y . . . . . . . . . . . . . . . . . . . . . . . . . .
    . . R . . R . . . R . Y . Y Y Y . Y . G . G . G . G . . . G . G . . . G . Y . . . . . . . . . . . . . . . . . . . . . . . . . .
    . . R . . R . R R R . Y . . . Y . Y . G G G . G . G G G . G . G G G . G . Y . . . . . . . . . . . . . . . . . . . . . . . . . .
    . . R . . R . R . . . Y . Y Y Y . Y . . . G . G . . . G . G . G . G . G . Y . . . . . . . . . . . . . . . . . . . . . . . . . .
    . . R . . R . R R R . Y . . . . . Y . . . G . G . G G G . G . G G G . G . Y . . . . . . . . . . . . . . . . . . . . . . . . . .
    . . . . . R . . . . . Y . . . . . Y . . . . . G . . . . . G . . . . . G . Y . . . . . . . . . . . . . . . . . . . . . . . . . .
    Y Y Y Y Y Y Y Y Y Y Y Y . . . . . Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . . . . . . . . . . . . . . . . . . .
    

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33. Value Objects
    

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34. new Bitmap()
    new BitmapBlock()
    new BitmapLine()
    

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35. Dot Matrix
    Fonts
    

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36. final class AdvancedDotDigital extends Font
    {
    protected static $chars = [
    "0" => "01111110\n11111111\n11000011\n11000011\n11000011\n11000011\n11000011\n11000011\n11000011\n11000011\n11111111\n01111110",
    "1" => "00011000\n00111000\n01111000\n11011000\n00011000\n00011000\n00011000\n00011000\n00011000\n00011000\n11111111\n11111111",
    "2" => "01111110\n11111111\n11000011\n00000011\n00000011\n01111111\n11111110\n11000000\n11000000\n11000000\n11111111\n11111111",
    "3" => "01111110\n11111111\n11000011\n00000011\n00000011\n00111110\n00111110\n00000011\n00000011\n11000011\n11111111\n01111110",
    "4" => "11000011\n11000011\n11000011\n11000011\n11000011\n11000011\n11111111\n11111111\n00000011\n00000011\n00000011\n00000011",
    "5" => "11111111\n11111111\n11000000\n11000000\n11111110\n11111111\n00000011\n00000011\n00000011\n11000011\n11111111\n01111110",
    "6" => "01111110\n11111111\n11000011\n11000000\n11111110\n11111111\n11000011\n11000011\n11000011\n11000011\n11111111\n01111110",
    "7" => "11111111\n11111111\n11000110\n00000110\n00001100\n00001100\n00011000\n00011000\n00110000\n00110000\n00110000\n00110000",
    "8" => "01111110\n11111111\n11000011\n11000011\n11000011\n01111110\n01111110\n11000011\n11000011\n11000011\n11111111\n01111110",
    "9" => "01111110\n11111111\n11000011\n11000011\n11000011\n11000011\n11111111\n01111111\n00000011\n11000011\n11111111\n01111110",
    "m" => "0000000000\n0000000000\n0000000000\n0000000000\n0000000000\n1111101110\n1111111111\n1100110011\n1100110011\n1100110011\n1100110011\n1100110011\n1100110011",
    "X" => "1100000000011\n0110000000110\n0011000001100\n0001100011000\n0000110110000\n0000011100000\n0000011100000\n0000110110000\n0001100011000\n0011000001100\n0110000000110\n1100000000011",
    "O" => "0000111110000\n0011111111100\n0111000001110\n0110000000110\n1100000000011\n1100000000011\n1100000000011\n1100000000011\n0110000000110\n0111000001110\n0011111111100\n0000111110000",
    ":" => "0000\n0000\n0110\n0110\n0000\n0000\n0000\n0000\n0110\n0110\n0000\n0000",
    "-" => "0000000000000\n0000000000000\n0000000000000\n0000000000000\n0000000000000\n0011111111100\n0011111111100\n0000000000000\n0000000000000\n0000000000000\n0000000000000\n0000000000000",
    ];
    }
    

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37. Problem 4
    How to get updates?
    

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38. inotify
    

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39. inotify_init() : filedescriptor
    inotify_add_watch($fd, $path, $mask) : watchDescriptorId
    inotify_rm_watch($fd, $wdId)
    inotify_read($fd) : event[]
    IN_MODIFY
    IN_CREATE
    IN_ALL_EVENTS
    IN_OPEN
    ...
    

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40. class Watcher
    {
    public function __construct($dir, LoopInterface $loop)
    {
    $fd = inotify_init();
    stream_set_blocking(fd, 0);
    inotify_add_watch($fd, $dir, IN_MODIFY);
    $loop->addReadStream($fd,
    function($fd) {
    foreach(inotify_read($fd) as $events) {
    //process change
    }
    }
    )
    }
    }
    

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41. Problem 5
    How to combine I/O?
    

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42. interface Layout
    {
    /**
    * @return Instruction[]
    */
    public function toInstructions();
    }
    

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43. class NextAthlete implements Layout
    {
    private $name;
    private $team;
    private $attempt;
    private $place = null;
    private $height = null;
    public function __construct($name, $team, $attempt, $place = null, $height = null)
    {
    $this->name = $name;
    $this->team = $team;
    $this->attempt = $attempt;
    $this->place = $place;
    $this->height = $height;
    }
    /**
    * @return Instruction[]
    */
    public function toInstructions()
    {
    $instructions = [];
    $name = (new Text(strtoupper($this->name), RingMatrix::class, "Y"))->toBitmap();
    $instructions[] = new Bitmap(0, 0, $name);
    $team = (new Text(strtoupper($this->team), SquareDotDigital::class, "R"))->toBitmap();
    $instructions[] = new Bitmap(64 - $team->getLength(), 11, $team);
    //some other conversion from data to instructions
    return $instructions;
    }
    }
    

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44. Problem 6
    How to send own layouts?
    

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45. PHP TCP
    server
    

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46. $loop = Factory::create();
    $server = new Server($loop);
    $server->on('connection', function (Connection $connection) {
    echo sprintf("%s came online\n", $connection->getRemoteAddress());
    $connection->on('close', function(Stream $stream) use ($connection) {
    echo sprintf("%s went offline\n", $connection->getRemoteAddress());
    });
    });
    $server->listen('6000', '0.0.0.0');
    $loop->run();
    

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47. Command
    pattern
    

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48. {
    "commandName":"Nortuni.FieldScoreboardManager.Commands.ShowLayout",
    "payload": {
    "scoreBoardId": "LED01",
    "layoutName": "TwoLines",
    "data": {
    "line1": "TEAM",
    "line2": "ARCTIC"
    }
    }
    }
    

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49. $loop = Factory::create();
    $deviceServer = new Server($loop);
    $commandServer = new Server($loop);
    $deviceServer->on('connection', function (Connection $connection) {
    //do some stuff
    });
    $commandServer->on('connection', function (Connection $connection) {
    $connection->on('data', function() {
    //parse json to command
    //dispatch command
    })
    });
    $deviceServer->listen('6000', '0.0.0.0');
    $commandServer->listen('6001', '0.0.0.0');
    $loop->run();
    

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50. Problem 7
    How to open up control?
    

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51. $socketServer = new Server($loop);
    $webserver = new React\Http\Server($socketServer);
    $webserver->on('request', function ($request, $response) {
    //just like a normal controller method
    //$response is a writable stream
    });
    $socket->listen(8080);
    

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52. Problem 8
    How to get current state?
    

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53. websockets
    

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54. composer require cboden/ratchet
    

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55. class WebSocketConnector implements MessageComponentInterface
    {
    private $clients;
    public function __construct() {
    $this->clients = new SplObjectStorage;
    }
    public function onOpen(ConnectionInterface $connection)
    {
    $this->clients->attach($conn);
    }
    public function onClose(ConnectionInterface $connection)
    {
    $this->clients->detach($connection);
    }
    public function onError(ConnectionInterface $connection, \Exception $e)
    {
    $connection->close();
    }
    public function onMessage(ConnectionInterface $from, $msg)
    {
    //process data
    }
    public function sendToClients($data)
    {
    foreach($this->clients as $client) {
    $client->send($data);
    }
    }
    }
    

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56. $socketServer = new Ratchet\App('192.168.15.100', 8080, '0.0.0.0', $loop);
    $socketServer->route('/field', new WebSocketConnector(), ['*']);
    

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57. var connection = null;
    var connect = function() {
    connection = new WebSocket('ws://192.168.15.100:8080/field');
    connection.onopen = function() {
    //log or ...
    };
    connection.onmessage = function(message) {
    //process message.data
    }
    connection.onclose = function() {
    connection = null;
    setTimeout(connect, 1000);
    };
    }
    var dispatch = function(data) {
    if(connection && connection.readyState == WebSocket.OPEN) {
    connection.send(data);
    }
    };
    

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58. Problem 9
    How to automate?
    

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59. {
    "commandName":"Nortuni.FieldScoreboardManager.Commands.ShowSlideshow",
    "payload": {
    "scoreBoardId":"LED01",
    "interval":"20",
    "screens":[
    {
    "layoutName":"MeetingName",
    "data": {
    "line1":"PHPGENT",
    "line2":"MEETUP",
    "line3":"",
    "line4":"WELCOME"
    }
    },
    {
    "layoutName":"MeetingName",
    "data": {
    "line1":"",
    "line2":"TEAMLEADER",
    "line3":"CRM",
    "line4":""
    }
    }
    ]
    }
    }
    

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60. timers
    

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61. $this->timer = $this->loop->addPeriodicTimer($interval, function() {
    $this->showNextSlide();
    });
    

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62. it works
    for now
    

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63. my experiences
    

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64. async programming in PHP
    is possible
    

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65. php is stable enough
    for long running processes
    

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66. reactphp is a
    mature and rich library
    

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67. I use reactphp
    in production
    

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68. I shouldn't
    use php for this
    

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69. Questions?
    

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70. sponsorship
    info@team-arctic.be
    

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71. Stijn Vannieuwenhuyse
    @stijnvnh
    https://joind.in/talk/822f4
    

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