Add support of async transitions. Require enqueue lib.

README.md

@@ -1,5 +1,44 @@
 # Process virtual machine
 
+The library provides us with a frame to build a [workflow](https://en.wikipedia.org/wiki/Workflow), business processes such as [BPMN](http://www.bpmn.org/). 
+It works like this: you build a process. It contains nodes and transitions between them. The process could be saved and used later. 
+The process could be executed with process engine. The processes could be visualized.
+
+It is backed up by [workflow nets (WF-nets)](https://en.wikipedia.org/wiki/Petri_net) mathematical model and [graphs theory](https://en.wikipedia.org/wiki/Graph_theory).
+
+## The "Hello world!" example
+
+Let's build our first process and execute it. It'll contain one single task that prints "Hello world" to the output.  
+
+```php
+<?php
+namespace Acme;
+
+use Formapro\Pvm\DefaultBehaviorRegistry;
+use Formapro\Pvm\CallbackBehavior;
+use Formapro\Pvm\ProcessEngine;
+use Formapro\Pvm\Process;
+
+$registry = new DefaultBehaviorRegistry();
+$registry->register('hello_world', new CallbackBehavior(function() {
+    echo 'Hello world';
+}));
+
+$process = new Process();
+$node = $process->createNode();
+$node->setLabel('Shouts "Hello world!"');
+$node->setBehavior('hello_world');
+
+$transition = $process->createTransition(null, $node);
+$token = $process->createToken($transition);
+
+(new ProcessEngine($registry))->proceed($token);
+```
+
+Here's the process diagram:
+
+![Hello world graph](docs/images/hello_world_example.png)
+
 ## Developed by Forma-Pro
 
 Forma-Pro is a full stack development company which interests also spread to open source development. 

composer.json

@@ -11,12 +11,16 @@
     },
     "require": {
         "php": "^5.5.0|^7.0",
-        "makasim/yadm": "@dev",
+        "makasim/values": "@dev",
         "mongodb/mongodb": "^1",
         "symfony/console": "^3.1",
         "graphp/graphviz": "^0.2.1",
         "ramsey/uuid": "^3"
     },
+    "suggest": {
+        "enqueue/enqueue": "Install the Enqueue library to be able to process tasks async (by using MQ).",
+        "makasim/yadm": "Install the Yadm library to be able to persist store in MongoDB"
+    },
     "extra": {
         "branch-alias": {
             "dev-master": "0.1.x-dev"

examples/fork-join.php

@@ -4,7 +4,7 @@
 use Formapro\Pvm\DefaultBehaviorRegistry;
 use Formapro\Pvm\EchoBehavior;
 use Formapro\Pvm\Exception\InterruptExecutionException;
-use Formapro\Pvm\MongoProcessStorage;
+use Formapro\Pvm\Yadm\MongoProcessStorage;
 use Formapro\Pvm\ProcessEngine;
 use Formapro\Pvm\Token;
 use Formapro\Pvm\Process;

examples/fork-join2.php

@@ -4,7 +4,7 @@
 use Formapro\Pvm\DefaultBehaviorRegistry;
 use Formapro\Pvm\EchoBehavior;
 use Formapro\Pvm\Exception\InterruptExecutionException;
-use Formapro\Pvm\MongoProcessStorage;
+use Formapro\Pvm\Yadm\MongoProcessStorage;
 use Formapro\Pvm\ProcessEngine;
 use Formapro\Pvm\Token;
 use Formapro\Pvm\Process;

src/AsyncTransitionIsNotConfigured.php

@@ -0,0 +1,10 @@
+<?php
+namespace Formapro\Pvm;
+
+class AsyncTransitionIsNotConfigured implements AsyncTransition
+{
+    public function transition(array $tokens)
+    {
+        throw new \LogicException('The async transitions is not configured. To be able to start using async transition you have to use enqueue library and its bridge classes or implement AsyncTransition interface yourself and provide it to the process engine.');
+    }
+}

src/Enqueue/AsyncTransition.php

@@ -0,0 +1,36 @@
+<?php
+namespace Formapro\Pvm\Enqueue;
+
+use Enqueue\Client\ProducerInterface;
+use Formapro\Pvm\Token;
+
+class AsyncTransition implements \Formapro\Pvm\AsyncTransition
+{
+    /**
+     * @var ProducerInterface
+     */
+    private $producer;
+
+    /**
+     * @param ProducerInterface $producer
+     */
+    public function __construct(ProducerInterface $producer)
+    {
+        $this->producer = $producer;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function transition(array $tokens)
+    {
+        foreach ($tokens as $token) {
+            /** @var Token $token */
+
+            $this->producer->send(HandleAsyncTransitionProcessor::TOPIC, [
+                'process' => $token->getProcess()->getId(),
+                'token' => $token->getId(),
+            ]);
+        }
+    }
+}

src/Enqueue/HandleAsyncTransitionProcessor.php

@@ -0,0 +1,75 @@
+<?php
+namespace Formapro\Pvm\Enqueue;
+
+use Enqueue\Client\TopicSubscriberInterface;
+use Enqueue\Consumption\Result;
+use Enqueue\Psr\PsrContext;
+use Enqueue\Psr\PsrMessage;
+use Enqueue\Psr\PsrProcessor;
+use Enqueue\Util\JSON;
+use Formapro\Pvm\Process;
+use Formapro\Pvm\ProcessEngine;
+use Formapro\Pvm\ProcessStorage;
+use Psr\Log\NullLogger;
+
+class HandleAsyncTransitionProcessor implements PsrProcessor, TopicSubscriberInterface
+{
+    const TOPIC = 'pvm_handle_async_transition';
+
+    /**
+     * @var ProcessEngine
+     */
+    private $processEngine;
+
+    /**
+     * @var ProcessStorage
+     */
+    private $processExecutionStorage;
+
+    /**
+     * @param ProcessEngine $processEngine
+     * @param ProcessStorage $processExecutionStorage
+     */
+    public function __construct(ProcessEngine $processEngine, ProcessStorage $processExecutionStorage)
+    {
+        $this->processEngine = $processEngine;
+        $this->processExecutionStorage = $processExecutionStorage;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function process(PsrMessage $psrMessage, PsrContext $psrContext)
+    {
+        if ($psrMessage->isRedelivered()) {
+            return Result::reject('The message failed. Remove it');
+        }
+
+        $data = JSON::decode($psrMessage->getBody());
+
+        /** @var Process $process */
+        if (false == $process = $this->processExecutionStorage->get($data['process'])) {
+            return Result::reject('Process was not found');
+        }
+
+        if (false == $token = $process->getToken($data['token'])) {
+            return Result::reject('No such token');
+        }
+
+        try {
+            $this->processEngine->proceed($token, new NullLogger());
+        } finally {
+            $this->processExecutionStorage->persist($process);
+        }
+
+        return self::ACK;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public static function getSubscribedTopics()
+    {
+        return [static::TOPIC];
+    }
+}

src/Node.php

@@ -23,7 +23,7 @@ class Node
 
     public function __construct()
     {
-        $this->setId(UUID::generate());
+        $this->setId(Uuid::generate());
     }
 
     /**

src/NullProcessStorage.php

@@ -0,0 +1,20 @@
+<?php
+namespace Formapro\Pvm;
+
+class NullProcessStorage implements ProcessStorage
+{
+    /**
+     * {@inheritdoc}
+     */
+    public function persist(Process $process)
+    {
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function get($id)
+    {
+        throw new \LogicException(sprintf('The process with id "%s" could not be found', $id));
+    }
+}

src/ProcessEngine.php

@@ -16,7 +16,7 @@ class ProcessEngine
     /**
      * @var ProcessStorage
      */
-    private $processStorage;
+    private $processExecutionStorage;
 
     /**
      * @var AsyncTransition
@@ -40,17 +40,17 @@ class ProcessEngine
 
     /**
      * @param BehaviorRegistry $behaviorRegistry
-     * @param ProcessStorage $processStorage
+     * @param ProcessStorage $processExecutionStorage
      * @param AsyncTransition $asyncTransition
      */
     public function __construct(
         BehaviorRegistry $behaviorRegistry,
-        ProcessStorage $processStorage,
-        AsyncTransition $asyncTransition
+        ProcessStorage $processExecutionStorage = null,
+        AsyncTransition $asyncTransition = null
     ) {
         $this->behaviorRegistry = $behaviorRegistry;
-        $this->processStorage = $processStorage;
-        $this->asyncTransition = $asyncTransition;
+        $this->processExecutionStorage = $processExecutionStorage ?: new NullProcessStorage();
+        $this->asyncTransition = $asyncTransition ?: new AsyncTransitionIsNotConfigured();
         $this->asyncTokens = [];
         $this->waitTokens = [];
     }
@@ -73,8 +73,11 @@ public function proceed(Token $token, LoggerInterface $logger = null)
         try {
             $this->log('Start execution: process: %s, token: %s', $token->getProcess()->getId(), $token->getId());
             $this->doProceed($token);
-            $this->processStorage->saveExecution($token->getProcess());
-            $this->asyncTransition->transition($this->asyncTokens);
+            $this->processExecutionStorage->persist($token->getProcess());
+
+            if ($this->asyncTokens) {
+                $this->asyncTransition->transition($this->asyncTokens);
+            }
 
             return $this->waitTokens;
         } catch (\Exception $e) {

src/ProcessStorage.php

@@ -8,4 +8,14 @@ interface ProcessStorage
      * @param Process $process
      */
     public function persist(Process $process);
+
+    /**
+     * @param string $id
+     *
+     * @throw \LogicException if there is no such process
+     *
+     * @return Process
+     */
+    public function get($id);
+
 }

src/Token.php

@@ -19,7 +19,7 @@ class Token
 
     public function __construct()
     {
-        $this->setId(UUID::generate());
+        $this->setId(Uuid::generate());
     }
 
     /**

src/Transition.php

@@ -32,7 +32,7 @@ class Transition
 
     public function __construct()
     {
-        $this->setId(UUID::generate());
+        $this->setId(Uuid::generate());
         $this->setWeight(1);
         $this->setAsync(false);
         $this->setActive(true);

src/UUID.php → src/Uuid.php

@@ -1,8 +1,7 @@
 <?php
 namespace Formapro\Pvm;
 
-
-class UUID
+class Uuid
 {
     public static function generate()
     {