Dutch php a short tale about state machine

Dutch php a short tale about state machine

• 1.
  A SHORT TALEABOUT STATE MACHINE
• 2.
  Once upon atime…
• 3.
  Kelly
• 5.
  final class Payment { privatebool $pending = false; }
• 7.
  Th e end ofchapter 1
• 8.
  A few dayslater
• 10.
  final class Payment { privatebool $pending = false; private bool $failed = false; }
• 12.
  final class Payment { privatebool $pending = false; private bool $failed = false; }
• 13.
  final class Payment { publicconst NEW = 1; public const PENDING = 2; public const FAILED = 3; private int $state = self::NEW; } ?
• 15.
  State Machine
• 16.
  (Q, Σ, δ,q0, F) Q = a fi nite set of states Σ = a fi nite, nonempty input alphabet δ = a series of transition functions q0 = the starting state F = the set of accepting states
• 17.
  NEW PENDING FAILED PAID Create Pay Fail
• 18.
  Let’s do theresearch!
• 19.
  De fi ne possible statesand relation between them Protect business rules Integrate other services on transitions What do we expect?
• 20.
  WinzouStateMachine
• 21.
  Callback’s execution incon fi g fi le Used heavily in Sylius Con fi gurable arguments of service Services have to be public in order to integrate them with state machine Without stable release, yet battle-tested and robust
• 24.
  $config = [ 'graph' =>'payment' , 'property_path' => 'state' , 'states' => ['new','pending','failed','paid'] , 'transitions' => [ 'process' => [ 'from' => ['new'] , 'to' => 'pending' , ] , 'fail' => [ 'from' => ['pending'] , 'to' => 'failed' , ] , 'pay' => [ 'from' => ['pending'] , 'to' => 'paid' , ] , ] , ];
• 25.
  $config = [ 'graph' =>'payment' , 'property_path' => 'state' , 'states' => ['new','pending','failed','paid'], 'transitions' => [ 'process' => [ 'from' => ['new'] , 'to' => 'pending' , ] , 'fail' => [ 'from' => ['pending'] , 'to' => 'failed' , ] , 'pay' => [ 'from' => ['pending'] , 'to' => 'paid' , ] , ] , ];
• 26.
  $config = [ 'graph' =>'payment' , 'property_path' => 'state', 'states' => ['new','pending','failed','paid'] , 'transitions' => [ 'process' => [ 'from' => ['new'] , 'to' => 'pending' , ] , 'fail' => [ 'from' => ['pending'] , 'to' => 'failed' , ] , 'pay' => [ 'from' => ['pending'] , 'to' => 'paid' , ] , ] , ];
• 27.
  $config = [ 'graph' =>'payment' , 'property_path' => 'state' , 'states' => ['new','pending','failed','paid'], 'transitions' => [ 'process' => [ 'from' => ['new'] , 'to' => 'pending' , ] , 'fail' => [ 'from' => ['pending'] , 'to' => 'failed' , ] , 'pay' => [ 'from' => ['pending'] , 'to' => 'paid' , ] , ] , ];
• 28.
  Symfony Work fl ow
• 29.
  Maintained by Symfony Flexsupport Work fl ow & state machine support Execution of external services with events XML / YAML / PHP support out-of-the-box Best documentation hands down
• 32.
  $definitionBuilder = newDefinitionBuilder() ; $definition = $definitionBuilder->addPlaces(['new','pending','failed','paid'] ) ->addTransition(new Transition('process', 'new', 'pending') ) ->addTransition(new Transition('fail', [‘pending'], 'failed') ) ->addTransition(new Transition('pay', 'pending', 'paid') ) ->build( ) ; $singleState = true ; $property = 'state' ; $marking = new MethodMarkingStore($singleState, $property) ; $workflow = new Workflow($definition, $marking, null, 'payment');
• 33.
  $definitionBuilder = newDefinitionBuilder() ; $definition = $definitionBuilder->addPlaces(['new','pending','failed','paid'] ) ->addTransition(new Transition('process', 'new', 'pending') ) ->addTransition(new Transition('fail', ['pending'], 'failed') ) ->addTransition(new Transition('pay', 'pending', 'paid') ) ->build( ) ; $singleState = true ; $property = 'state' ; $marking = new MethodMarkingStore($singleState, $property) ; $workflow = new Workflow($definition, $marking, null, 'payment');
• 34.
  $definitionBuilder = newDefinitionBuilder() ; $definition = $definitionBuilder->addPlaces(['new','pending','failed','paid'] ) ->addTransition(new Transition('process', 'new', 'pending') ) ->addTransition(new Transition('fail', [‘pending'], 'failed') ) ->addTransition(new Transition('pay', 'pending', 'paid') ) ->build( ) ; $singleState = true ; $property = 'state' ; $marking = new MethodMarkingStore($singleState, $property) ; $workflow = new Workflow($definition, $marking, null, 'payment');
• 35.
  Finite
• 36.
  Oldest and mostpopular implementation (in terms of stars) Least used implementation (in terms of daily installs according to packagist) Extendability with events & callbacks de fi nition Perhaps reached its EOL (https://github.com/yohang/Finite/issues/161) It is said to be little bit heavier implementation compared to Winzou
• 39.
  Back to the st ory…
• 40.
  final class Payment { publicconst NEW = 'new'; private string $state = self::NEW; public function getState(): string { return $this->state; } public function setState(string $state): void { $this->state = $state } }
• 41.
  WinzouStateMachine
• 42.
  $payment = newPayment() ; $stateMachine = new StateMachine($payment, $config) ; $stateMachine->apply('process') ; $stateMachine->apply('fail');
• 43.
  Symfony Work fl ow
• 44.
  $payment = newPayment() ; $workflow->apply($payment, 'process') ; $workflow->apply($payment, 'fail');
• 47.
  Th e end ofchapter 2
• 48.
  New adventur e
• 50.
  WinzouStateMachine
• 51.
  final class InventoryOperato r { publicfunction __invoke(TransitionEvent $transitionEvent): voi d { $stateMachine = $transitionEvent->getStateMachine() ; /** @var Payment $payment * / $payment = $stateMachine->getObject() ; // Reduce inventory of bought product s } } $config = [ // .. . 'callbacks' => [ 'before' => [ 'reduce_amount' => [ 'on' => ['pay'] , 'do' => new InventoryOperator() , ] , ] , ] , ];
• 52.
  final class InventoryOperato r { publicfunction __invoke(TransitionEvent $transitionEvent): voi d { $stateMachine = $transitionEvent->getStateMachine() ; /** @var Payment $payment * / $payment = $stateMachine->getObject() ; // Reduce inventory of bought product s } } $config = [ // .. . 'callbacks' => [ 'before' => [ 'reduce_amount' => [ 'on' => ['pay'] , 'do' => new InventoryOperator() , ] , ] , ] , ];
• 53.
  final class InventoryOperato r { publicfunction __invoke(TransitionEvent $transitionEvent): voi d { $stateMachine = $transitionEvent->getStateMachine() ; /** @var Payment $payment * / $payment = $stateMachine->getObject() ; // Reduce inventory of bought product s } } $config = [ // .. . 'callbacks' => [ 'before' => [ 'reduce_amount' => [ 'on' => ['pay'] , 'do' => new InventoryOperator() , ] , ] , ] , ];
• 54.
  Guard Before After Callbacks types * Samecan be achieved with dispatched events
• 55.
  class StateMachine implementsStateMachineInterface { public function apply(/** */): void { // Guard callback if (!$this->can($transition)) { throw new SMException(); } // Before callback $this->setState('failed'); // After callback } }
• 56.
  final class InventoryOperato r { publicfunction __invoke(TransitionEvent $transitionEvent): voi d { $stateMachine = $transitionEvent->getStateMachine() ; /** @var Payment $payment * / $payment = $stateMachine->getObject() ; // Reduce inventory of bought product s } } $config = [ // .. . 'callbacks' => [ 'before' => [ 'reduce_amount' => [ 'on' => ['pay'] , 'do' => new InventoryOperator() , ] , ] , ] , ];
• 57.
  On -> transition From-> state To -> state Callbacks types
• 58.
  Symfony Work fl ow
• 59.
  $dispatcher = newEventDispatcher() ; $dispatcher->addListener ( 'workflow.payment.enter.paid', new PaymentPaidListener( ) ) ; $workflow = new Workflow($definition, $marking, $dispatcher, 'payment'); final class PaymentPaidListener { public function __invoke(EnterEvent $event): void { // Reduce inventory of bought products } }
• 60.
  $dispatcher = newEventDispatcher() ; $dispatcher->addListener ( 'workflow.payment.enter.paid', new PaymentPaidListener( ) ); $workflow = new Workflow($definition, $marking, $dispatcher, 'payment'); final class PaymentPaidListener { public function __invoke(EnterEvent $event): void { // Reduce inventory of bought products } }
• 61.
  $dispatcher = newEventDispatcher() ; $dispatcher->addListener( 'workflow.payment.enter.paid', new PaymentPaidListener( ) ) ; $workflow = new Workflow($definition, $marking, $dispatcher, 'payment'); final class PaymentPaidListener { public function __invoke(EnterEvent $event): void { // Reduce inventory of bought products } }
• 62.
  $dispatcher = newEventDispatcher() ; $dispatcher->addListener( 'workflow.payment.enter.paid', new PaymentPaidListener( ) ) ; $workflow = new Workflow($definition, $marking, $dispatcher, 'payment'); final class PaymentPaidListener { public function __invoke(EnterEvent $event): void { // Reduce inventory of bought products } }
• 63.
  $dispatcher = newEventDispatcher() ; $dispatcher->addListener( 'workflow.payment.enter.paid', new PaymentPaidListener( ) ) ; $workflow = new Workflow($definition, $marking, $dispatcher, 'payment'); final class PaymentPaidListener { public function __invoke(EnterEvent $event): void { // Reduce inventory of bought products } }
• 64.
  work fl ow.[place type] work fl ow.[work fl ow name].[placetype] work fl ow.[work fl ow name].[place type].[place name] Actions
• 65.
  leave -> currentplace enter -> which place(places) will be visited entered -> which place(places) were visited Types for places
• 66.
  work fl ow.[transition type] work fl ow.[work fl ow name].[transitiontype] work fl ow.[work fl ow name].[transition type].[transition name] Actions
• 67.
  guard -> possibilityto validate transition transition -> which transition will be executed completed -> which transition was executed announce -> which transition are available now Types for transitions
• 68.
  class Workflow implementsWorkflowInterface { public function apply(/** */ ) { $this->leave(/** */) ; $this->transition(/** */); $this->enter(/** */) ; /** Making transition */ $this->markingStore->setMarking($payment, 'failed', $context) ; $this->entered(/** */) ; $this->completed(/** */) ; $this->announce(/** */) ; } }
• 71.
  WinzouStateMachine
• 72.
  final class BlockAuthorizer { publicfunction __invoke(): bool { return false; } } $config = [ /** ... * / 'callbacks' => [ /** ... * / 'guard' => [ 'guard-blocked' => [ 'to' => ['blocked'] , 'do' => new BlockedAuthorizer() , ] , ] , ] , ];
• 73.
  Symfony Work fl ow
• 74.
  final class BlockedGuardListener { publicfunction __invoke(GuardEvent $event): void { $event->setBlocked(true); } } $dispatcher->addListener ( 'workflow.payment.guard.block' , new BlockedGuardListener( ) ) ;
• 76.
  Th e end ofchapter 3
• 77.
  Summary
• 78.
  De fi ne possible statesand relation between them Protect business rules (with guards) Trigger other services on transitions Ease to add new possible transitions Trigger other state changes as a reaction
• 79.
  WinzouStateMachine vs SymfonyWork fl ow
• 81.
  Why should youcare?
• 82.
  Common issues
• 83.
  Business logic wiredup in con fi guration fi les
• 84.
  Describe problem withstate machine but implement directly in code
• 85.
  Possibility to destroystate of entities if state machine is omitted
• 87.
  😭
• 88.
  setState(…)
• 89.
  lchrusciel/RawStateMachine
• 90.
  @Sylius Thank you! @lukaszchrusciel