Event Machine Example

EventMachine_Example.postman_collection.json

{
	"variables": [],
	"info": {
		"name": "EventMachine Example",
		"_postman_id": "89698ba0-98f0-cc94-2f71-9f19c183e3f3",
		"description": "",
		"schema": "https://schema.getpostman.com/json/collection/v2.0.0/collection.json"
	},
	"item": [
		{
			"name": "RegisterUser",
			"request": {
				"url": "http://localhost:8080/api/messagebox/RegisterUser",
				"method": "POST",
				"header": [
					{
						"key": "Content-Type",
						"value": "application/json",
						"description": ""
					},
					{
						"key": "Accept",
						"value": "application/json",
						"description": ""
					}
				],
				"body": {
					"mode": "raw",
					"raw": "{\n\t\"payload\": {\n\t\t\"userId\": \"932577dd-3593-47bd-8bd0-3bd7bf7e111f\",\n\t\t\"email\": \"[email protected]\",\n\t\t\"username\": \"codeliner\"\n\t}\n}"
				},
				"description": "Register a new user"
			},
			"response": []
		},
		{
			"name": "ChangeUsername",
			"request": {
				"url": "http://localhost:8080/api/messagebox/ChangeUsername",
				"method": "POST",
				"header": [
					{
						"key": "Content-Type",
						"value": "application/json",
						"description": ""
					},
					{
						"key": "Accept",
						"value": "application/json",
						"description": ""
					}
				],
				"body": {
					"mode": "raw",
					"raw": "{\n\t\"payload\": {\n\t\t\"userId\": \"932577dd-3593-47bd-8bd0-3bd7bf7e111f\",\n\t\t\"newUsername\": \"your name here\"\n\t}\n}"
				},
				"description": "Change name of a user"
			},
			"response": []
		}
	]
}

global.php

<?php
declare(strict_types = 1);

namespace App\Config;

use App\Model\UserDescription;

return [
    'environment' => getenv('PROOPH_ENV')?: 'prod',
    'pdo' => [
        'dsn' => getenv('PDO_DSN'),
        'user' => getenv('PDO_USER'),
        'pwd' => getenv('PDO_PWD'),
    ],
    'mongo' => [
        'server' => getenv('MONGO_SERVER'),
        'db' => getenv('MONGO_DB_NAME'),
    ],
    'rabbit' => [
        'connection' => [
            'host' => getenv('RABBIT_HOST')?: 'rabbit',
            'port' => (int)getenv('RABBIT_PORT')?: 5672,
            'login' => getenv('RABBIT_USER')?: 'event-machine',
            'password' => getenv('RABBIT_PWD')?: 'event-machine',
            'vhost' => getenv('RABBIT_VHOST')?: '/event-machine',
            'persistent' => (bool)getenv('RABBIT_PERSISTENT')?: false,
            'read_timeout' => (int)getenv('RABBIT_READ_TIMEOUT')?: 1, //sec, float allowed
            'write_timeout' => (int)getenv('RABBIT_WRITE_TIMEOUT')?: 1, //sec, float allowed,
            'heartbeat' => (int)getenv('RABBIT_HEARTBEAT')?: 0,
            'verify' => false
        ],
        'ui_exchange' => getenv('RABBIT_UI_EXCHANGE')?: 'ui-exchange',
    ],
    'event_machine' => [
        'descriptions' => [
            UserDescription::class
        ]
    ]
];

UserDescription.php

<?php
declare(strict_types = 1);

namespace App\Model;

use Prooph\Common\Messaging\Message;
use Prooph\EventMachine\Aggregate\Exception\AggregateNotFound;
use Prooph\EventMachine\EventMachine;
use Prooph\EventMachine\EventMachineDescription;
use Prooph\EventMachine\JsonSchema\JsonSchema;
use Prooph\EventMachine\Persistence\Stream;
use React\Promise\Deferred;

final class UserDescription implements EventMachineDescription
{
    const COMMAND_REGISTER_USER = "RegisterUser";
    const COMMAND_CHANGE_USERNAME = "ChangeUsername";
    const EVENT_USER_WAS_REGISTERED = "UserWasRegistered";
    const EVENT_USERNAME_WAS_CHANGED = "UsernameWasChanged";
    const QUERY_USER = 'User';
    const AGGREGATE_USER = "User";
    const IDENTIFIER = 'userId';

    private static $userSchema;

    public static function describe(EventMachine $eventMachine): void
    {
        self::describeMessages($eventMachine);
        self::describeRegisterUser($eventMachine);
        self::describeChangeUsername($eventMachine);
        self::describeProjectUser($eventMachine);
        self::describeQueryUser($eventMachine);
    }
    private static function describeMessages(EventMachine $eventMachine): void
    {
        $userId = ['type' => 'string', 'pattern' => '^[A-Za-z0-9-]{36}$'];
        $username = ['type' => 'string', 'minLength' => 1];
        $email = ['type' => 'string', 'format' => 'email'];

        self::$userSchema = JsonSchema::object([
            'userId' => $userId,
            'username' => $username,
            'email' => $email
        ]);

        $eventMachine->registerCommand(self::COMMAND_REGISTER_USER, self::$userSchema);
        $eventMachine->registerCommand(self::COMMAND_CHANGE_USERNAME, JsonSchema::object([
            'userId' => $userId,
            'newUsername' => $username,
        ]));
        $eventMachine->registerEvent(self::EVENT_USER_WAS_REGISTERED, JsonSchema::object([
            'userId' => $userId,
            'username' => $username,
            'email' => $email
        ]));
        $eventMachine->registerEvent(self::EVENT_USERNAME_WAS_CHANGED, JsonSchema::object([
            'userId' => $userId,
            'oldUsername' => $username,
            'newUsername' => $username
        ]));
    }
    private static function describeRegisterUser(EventMachine $eventMachine): void
    {
        $eventMachine->process(self::COMMAND_REGISTER_USER)
            ->withNew(self::AGGREGATE_USER)
            ->identifiedBy(self::IDENTIFIER)
            ->handle(function(Message $registerUser) {
                yield [self::EVENT_USER_WAS_REGISTERED, $registerUser->payload()];
            })
            ->recordThat(self::EVENT_USER_WAS_REGISTERED)
            ->apply(function (Message $userWasRegistered) {
                $userState = $userWasRegistered->payload();
                return $userState;
            });
    }
    private static function describeChangeUsername(EventMachine $eventMachine): void
    {
        $eventMachine->process(self::COMMAND_CHANGE_USERNAME)
            ->withExisting(self::AGGREGATE_USER)
            ->handle(function (array $userState, Message $changeUsername) {
                yield [self::EVENT_USERNAME_WAS_CHANGED, [
                    'userId' => $userState[self::IDENTIFIER],
                    'oldUsername' => $userState['username'],
                    'newUsername' => $changeUsername->payload()['newUsername']
                ]];
            })
            ->recordThat(self::EVENT_USERNAME_WAS_CHANGED)
            ->apply(function(array $userState, Message $usernameWasChanged) {
                $userState['username'] = $usernameWasChanged->payload()['newUsername'];
                return $userState;
            });

        //Forward UserWasChanged event to UI using rabbitmq + stomp over websocket
        $eventMachine->on(self::EVENT_USERNAME_WAS_CHANGED, 'uiExchange');
    }

    private static function describeProjectUser(EventMachine $eventMachine): void
    {
        $eventMachine->watch(Stream::ofWriteModel())
            ->withAggregateProjection(self::AGGREGATE_USER, self::$userSchema);
    }

    private static function describeQueryUser(EventMachine $eventMachine): void
    {
        $eventMachine->registerQuery(self::QUERY_USER, JsonSchema::object([
            'userId' => JsonSchema::string()
        ]))->resolveWith(function (Message $getUser, Deferred $deferred) use ($eventMachine) {
            try {
                $deferred->resolve(
                    $eventMachine->loadAggregateState(self::AGGREGATE_USER, $getUser->payload()['userId'])
                );
            } catch (AggregateNotFound $error) {
                $deferred->reject($error);
            }

        })->returnType(JsonSchema::typeRef(self::AGGREGATE_USER));
    }
}