🆕 Introduce ES persistence with a FS event store.

Author: shouze

app.php

@@ -0,0 +1,34 @@
+<?php
+require_once __DIR__ . '/vendor/autoload.php';
+
+use Shouze\ParkedLife\Domain;
+use Shouze\ParkedLife\EventSourcing;
+use Shouze\ParkedLife\Adapters;
+use Shouze\ParkedLife\Ports;
+
+// 1. We start from pure domain code
+$userId = new Domain\UserId('shouze');
+$fleet = Domain\VehicleFleet::ofUser($userId);
+$platenumber = 'AM 069 GG';
+$fleet->registerVehicle($platenumber, 'My benz');
+$fleet->parkVehicle($platenumber, Domain\Location::fromString('4.1, 3.12'), new \DateTimeImmutable());
+
+// 2. We build our sourceable stream
+$streamName = new EventSourcing\StreamName(sprintf('vehicle_fleet-%s', $userId));
+$stream = new EventSourcing\Stream($streamName, $fleet->popRecordedChanges());
+
+// 3. We adapt the domain to the infra through event sourcing
+$serializer = new EventSourcing\EventSerializer(
+    new Domain\EventMapping,
+    new Symfony\Component\Serializer\Serializer(
+        [
+            new Symfony\Component\Serializer\Normalizer\PropertyNormalizer(
+                null,
+                new Symfony\Component\Serializer\NameConverter\CamelCaseToSnakeCaseNameConverter
+            )
+        ],
+        [ new Symfony\Component\Serializer\Encoder\JsonEncoder ]
+    )
+);
+$eventStore = new Adapters\FilesystemEventStore(__DIR__.'/var/eventstore', $serializer, new Ports\FileHelper);
+$eventStore->commit($stream);

composer.json

@@ -5,7 +5,9 @@
     "autoload": {
         "psr-4": { "Shouze\\ParkedLife\\": "src/" }
     },
-    "require": {},
+    "require": {
+        "symfony/serializer": "^3.1"
+    },
     "require-dev": {
         "behat/behat": "^3.2",
         "phpspec/phpspec": "^3.1",

composer.lock

@@ -0,0 +1,4 @@
+php app.php ; find var -type f | xargs cat                                                                                                   Dim 25 sep 23:22:08 2016
+{"event_name":"vehicle_was_registered.fleet.parkedlife","data":{"user_id":"shouze","platenumber":"AM 069 GG"}}
+{"event_name":"vehicle_was_described.fleet.parkedlife","data":{"user_id":"shouze","platenumber":"AM 069 GG","description":"My benz"}}
+{"event_name":"vehicle_was_parked.fleet.parkedlife","data":{"user_id":"shouze","platenumber":"AM 069 GG","latitude":4.1,"longitude":3.12,"timestamp":1474838529}}

events.sh

@@ -8,3 +8,5 @@ vendor/bin/behat --append-snippets --snippets-for=FeatureContext
 composer require --dev phpspec/phpspec
 # Create phpspec.yml with psr4_prefix
 vendor/bin/phpspec run
+# Add a decent serializer
+composer require "symfony/serializer"

history

@@ -0,0 +1,63 @@
+<?php
+declare(strict_types=1);
+
+namespace Shouze\ParkedLife\Adapters;
+
+use SplFileObject;
+use Shouze\ParkedLife\EventSourcing\EventStore;
+use Shouze\ParkedLife\EventSourcing\EventSerializer;
+use Shouze\ParkedLife\EventSourcing\Stream;
+use Shouze\ParkedLife\EventSourcing\StreamName;
+use Shouze\ParkedLife\Ports\FileHelper;
+
+class FilesystemEventStore implements EventStore
+{
+    private $baseDir;
+
+    private $eventSerializer;
+
+    private $fileHelper;
+
+    public function __construct(string $baseDir, EventSerializer $eventSerializer, FileHelper $fileHelper)
+    {
+        $this->baseDir = $baseDir;
+        $this->eventSerializer = $eventSerializer;
+        $this->fileHelper = $fileHelper;
+    }
+
+    public function commit(Stream $eventStream)
+    {
+        $filename = $this->filename($eventStream->getStreamName());
+        $content = '';
+        foreach ($eventStream->getChanges() as $change) {
+            $content .= $this->eventSerializer->serialize($change).PHP_EOL;
+        }
+
+        $this->fileHelper->appendSecurely($filename, $content);
+    }
+
+    public function fetch(StreamName $streamName): Stream
+    {
+        $filename = $this->filename($streamName);
+        $lines = $this->fileHelper->readIterator($this->filename($streamName));
+        $events = new ArrayIterator();
+        foreach ($lines as $serializedEvent) {
+            $events->append($this->eventSerializer->deserialize($serializedEvent));
+        }
+        $lines = null; // immediately removes the descriptor.
+
+        return new Stream($streamName, $events);
+    }
+
+    private function filename(StreamName $streamName): string
+    {
+        $hash = sha1((string)$streamName);
+
+        return
+            $this->baseDir.'/'.
+            substr($hash, 0, 2).'/'.
+            substr($hash, 2, 2).'/'.
+            $hash
+        ;
+    }
+}

src/Adapters/FilesystemEventStore.php

@@ -0,0 +1,18 @@
+<?php
+declare(strict_types=1);
+
+namespace Shouze\ParkedLife\Domain;
+
+use Shouze\ParkedLife\EventSourcing\EventMapping as AbstractEventMapping;
+
+final class EventMapping extends AbstractEventMapping
+{
+    public function __construct()
+    {
+        self::$mapping = [
+            'vehicle_was_registered.fleet.parkedlife' => VehicleWasRegistered::class,
+            'vehicle_was_described.fleet.parkedlife' => VehicleWasDescribed::class,
+            'vehicle_was_parked.fleet.parkedlife' => VehicleWasParked::class,
+        ];
+    }
+}

src/Domain/EventMapping.php

@@ -12,7 +12,7 @@ public function __construct(string $value)
         $this->value = $value;
     }
 
-    public function __toString()
+    public function __toString(): string
     {
         return $this->value;
     }

src/Domain/UserId.php

@@ -45,13 +45,20 @@ public function whenVehicleWasDescribed(VehicleWasDescribed $change)
     }
 
     public function parkVehicle(string $platenumber, Location $where, \DateTimeInterface $when)
+    {
+        $this->record(new VehicleWasParked($this->getAggregateId(), $platenumber, $where->getLatitude(), $where->getLongitude(), $when->getTimestamp()));
+    }
+
+    public function whenVehicleWasParked(VehicleWasParked $change)
     {
         try {
-            $vehicle = $this->vehicleWithPlatenumber($platenumber);
+            $vehicle = $this->vehicleWithPlatenumber($change->getPlatenumber());
         } catch (\LogicException $e) {
-            throw new \LogicException(sprintf('Cannot park unknown vehicle %s', $platenumber, 0, $e));
+            throw new \LogicException(sprintf('Cannot park unknown vehicle %s', $change->getPlatenumber(), 0, $e));
         }
 
+        $where = new Location($change->getLatitude(), $change->getLongitude());
+        $when = new \DateTimeImmutable(sprintf('@%ld', $change->getTimestamp()));
         $vehicle->park($where, $when);
     }
 

src/Domain/VehicleFleet.php

@@ -0,0 +1,53 @@
+<?php
+declare(strict_types=1);
+
+namespace Shouze\ParkedLife\Domain;
+
+use Shouze\ParkedLife\EventSourcing\Change;
+
+final class VehicleWasParked implements Change
+{
+    private $userId;
+
+    private $platenumber;
+
+    private $latitude;
+
+    private $longitude;
+
+    private $timestamp;
+
+    public function __construct(string $userId, string $platenumber, float $latitude, float $longitude, int $timestamp)
+    {
+        $this->userId = $userId;
+        $this->platenumber = $platenumber;
+        $this->latitude = $latitude;
+        $this->longitude = $longitude;
+        $this->timestamp = $timestamp;
+    }
+
+    public function getAggregateId(): string
+    {
+        return $this->userId;
+    }
+
+    public function getPlatenumber(): string
+    {
+        return $this->platenumber;
+    }
+
+    public function getLatitude(): float
+    {
+        return $this->latitude;
+    }
+
+    public function getLongitude(): float
+    {
+        return $this->longitude;
+    }
+
+    public function getTimestamp(): int
+    {
+        return $this->timestamp;
+    }
+}

src/Domain/VehicleWasParked.php

@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace Shouze\ParkedLife\EventSourcing;
 
@@ -36,7 +37,7 @@ public function popRecordedChanges(): \Iterator
 
         $this->recordedChanges = [];
 
-        return $pendingChanges;
+        return new \ArrayIterator($pendingChanges);
     }
 
     protected function record(Change $change)

src/EventSourcing/AggregateRoot.php

@@ -5,5 +5,5 @@
 
 interface Change
 {
-    public function getAggregateId();
+    public function getAggregateId(): string;
 }

src/EventSourcing/Change.php

@@ -0,0 +1,23 @@
+<?php
+declare(strict_types=1);
+
+namespace Shouze\ParkedLife\EventSourcing;
+
+abstract class EventMapping
+{
+    protected static $mapping = [];
+
+    public function getEventNameFor(Change $change): string
+    {
+        return $this->valueOfKeyIfExist(get_class($change), array_flip(self::$mapping));
+    }
+
+    private function valueOfKeyIfExist($key, array $array): string
+    {
+        if (false === array_key_exists($key, $array)) {
+            throw new \LogicException(sprintf('Missing key %s in the event mapping', $key));
+        }
+
+        return $array[$key];
+    }
+}