All aboard the Service Bus

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Robert Bašić https://robertbasic.com/ @robertbasic All aboard the Service Bus

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Robert Bašić ~ PHPSrbija #29 A new project appears

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Robert Bašić ~ PHPSrbija #29 Ready to build greatness

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Robert Bašić ~ PHPSrbija #29 Your creation

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Robert Bašić ~ PHPSrbija #29 // todo finish this

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Robert Bašić ~ PHPSrbija #29 // refactor me later

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Robert Bašić ~ PHPSrbija #29 // dirty hack to work around...

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Robert Bašić ~ PHPSrbija #29 Same old story

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Robert Bašić ~ PHPSrbija #29 Same old story ● An image gallery

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Robert Bašić ~ PHPSrbija #29 Same old story ● An image gallery ● Multiple currencies

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Robert Bašić ~ PHPSrbija #29 Same old story ● An image gallery ● Multiple currencies ● Coupons

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Robert Bašić ~ PHPSrbija #29 Same old story ● An image gallery ● Multiple currencies ● Coupons ● Sales

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Robert Bašić ~ PHPSrbija #29 Same old story ● An image gallery ● Multiple currencies ● Coupons ● Sales ● Reviews

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Robert Bašić ~ PHPSrbija #29 Same old story ● An image gallery ● Multiple currencies ● Coupons ● Sales ● Reviews ● With images

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Robert Bašić ~ PHPSrbija #29 Same old story ● An image gallery ● Multiple currencies ● Coupons ● Sales ● Reviews ● With images ● Old products

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Robert Bašić ~ PHPSrbija #29 Same old story ● An image gallery ● Multiple currencies ● Coupons ● Sales ● Reviews ● With images ● Old products ● Warehousing

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Robert Bašić ~ PHPSrbija #29 Been there, done that

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Robert Bašić ~ PHPSrbija #29 Command Query Responsibility Segregation

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Robert Bašić ~ PHPSrbija #29 CQRS

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Robert Bašić ~ PHPSrbija #29 CQRS

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Robert Bašić ~ PHPSrbija #29 CQRS ● Use cases

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Robert Bašić ~ PHPSrbija #29 CQRS ● Use cases ● Separation of concerns

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Robert Bašić ~ PHPSrbija #29 CQRS ● Use cases ● Separation of concerns ● Improved readability

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Robert Bašić ~ PHPSrbija #29 CQRS ● Use cases ● Separation of concerns ● Improved readability ● Improved performance

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Robert Bašić ~ PHPSrbija #29 Before CQRS db->update('products', $product, ['id' => $product['id']]); } public function getProductById($productId) { /* ... */ } }

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Robert Bašić ~ PHPSrbija #29 After CQRS (i) newPrice = Product\Price::fromString($newPrice, $currency); $this->product = $product; } public function newPrice() { return $this->newPrice; } public function product() { return $this->product; } }

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Robert Bašić ~ PHPSrbija #29 After CQRS (ii) product(); $newPrice = $command->newPrice(); if ($product->onSale()) { throw new \Exception("Can't update price of products that are on sale!"); } $product->updatePrice($newPrice); $this->repository->save($product); } }

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Robert Bašić ~ PHPSrbija #29 CQRS, the good

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Robert Bašić ~ PHPSrbija #29 CQRS, the good ● Smaller classes

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Robert Bašić ~ PHPSrbija #29 CQRS, the good ● Smaller classes ● Separated responsibilities

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Robert Bašić ~ PHPSrbija #29 CQRS, the good ● Smaller classes ● Separated responsibilities ● Faster writes and reads

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Robert Bašić ~ PHPSrbija #29 CQRS, the good ● Smaller classes ● Separated responsibilities ● Faster writes and reads ● Easier database queries

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Robert Bašić ~ PHPSrbija #29 CQRS, the bad

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Robert Bašić ~ PHPSrbija #29 CQRS, the bad ● More classes

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Robert Bašić ~ PHPSrbija #29 CQRS, the bad ● More classes ● Translation

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Robert Bašić ~ PHPSrbija #29 CQRS, the bad ● More classes ● Translation ● Complex syncing

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Robert Bašić ~ PHPSrbija #29 CQRS, the bad ● More classes ● Translation ● Complex syncing ● Eventual consistency

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Robert Bašić ~ PHPSrbija #29 Service Bus

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Robert Bašić ~ PHPSrbija #29 What is a service bus?

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Robert Bašić ~ PHPSrbija #29 Types of service buses

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Robert Bašić ~ PHPSrbija #29 Types of service buses ● Message type

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Robert Bašić ~ PHPSrbija #29 Types of service buses ● Message type ● Command bus

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Robert Bašić ~ PHPSrbija #29 Types of service buses ● Message type ● Command bus ● Event bus

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Robert Bašić ~ PHPSrbija #29 Types of service buses ● Message type ● Command bus ● Event bus ● Query bus

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Robert Bašić ~ PHPSrbija #29 Service buses in PHP

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Robert Bašić ~ PHPSrbija #29 Service buses in PHP ● Varying support for message types

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Robert Bašić ~ PHPSrbija #29 Service buses in PHP ● Varying support for message types ● Tactician

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Robert Bašić ~ PHPSrbija #29 Service buses in PHP ● Varying support for message types ● Tactician ● SimpleBus

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Robert Bašić ~ PHPSrbija #29 Service buses in PHP ● Varying support for message types ● Tactician ● SimpleBus ● Prooph Service Bus

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Robert Bašić ~ PHPSrbija #29 Command Bus

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Robert Bašić ~ PHPSrbija #29 Command Bus

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Robert Bašić ~ PHPSrbija #29 Commands

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Robert Bašić ~ PHPSrbija #29 Commands ● Messages about user intention

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Robert Bašić ~ PHPSrbija #29 Commands ● Messages about user intention ● CreateProduct, PutProductOnSale

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Robert Bašić ~ PHPSrbija #29 Commands ● Messages about user intention ● CreateProduct, PutProductOnSale ● Name reveals use case

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Robert Bašić ~ PHPSrbija #29 Commands ● Messages about user intention ● CreateProduct, PutProductOnSale ● Name reveals use case ● One command, one action

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Robert Bašić ~ PHPSrbija #29 Dispatching commands, HTTP getProduct($request->get('productid')); $command = new UpdateProductPrice( $request->get('price'), $request->get('currency'), $product ); $this->commandBus->dispatch($command); } private function getProduct($productId): Model\Product }

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Robert Bašić ~ PHPSrbija #29 Dispatching commands, CLI getProduct($input->get('productid')); $command = new UpdateProductPrice( $input->get('price'), $input->get('currency'), $product ); $this->commandBus->dispatch($command); } private function getProduct($productId): Model\Product }

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Robert Bašić ~ PHPSrbija #29 A command is always valid newPrice = Product\Price::fromString($newPrice, $currency); $this->product = $product; } public function newPrice() { return $this->newPrice; } public function product() { return $this->product; } }

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Robert Bašić ~ PHPSrbija #29 Command handlers product(); $newPrice = $command->newPrice(); if ($product->onSale()) { throw new \Exception("Can't update price of products that are on sale!"); } $product->updatePrice($newPrice); $this->repository->save($product); } }

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Robert Bašić ~ PHPSrbija #29 Command buses in PHP

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Robert Bašić ~ PHPSrbija #29 Command buses in PHP ● Tactician, SimpleBus, Prooph Service Bus

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Robert Bašić ~ PHPSrbija #29 Command buses in PHP ● Tactician, SimpleBus, Prooph Service Bus ● Differ in creation and configuration

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Robert Bašić ~ PHPSrbija #29 Command buses in PHP ● Tactician, SimpleBus, Prooph Service Bus ● Differ in creation and configuration ● Similar usage

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Robert Bašić ~ PHPSrbija #29 Command buses in PHP ● Tactician, SimpleBus, Prooph Service Bus ● Differ in creation and configuration ● Similar usage ● Plugins, middlewares

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Robert Bašić ~ PHPSrbija #29 Event Bus

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Robert Bašić ~ PHPSrbija #29 Event Bus

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Robert Bašić ~ PHPSrbija #29 Events

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Robert Bašić ~ PHPSrbija #29 Events ● Messages about past events

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Robert Bašić ~ PHPSrbija #29 Events ● Messages about past events ● After a command was handled

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Robert Bašić ~ PHPSrbija #29 Events ● Messages about past events ● After a command was handled ● ProductCreated, ProductPriceUpdated

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Robert Bašić ~ PHPSrbija #29 Events ● Messages about past events ● After a command was handled ● ProductCreated, ProductPriceUpdated ● Once dispatched, can’t be stopped

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Robert Bašić ~ PHPSrbija #29 Dispatching events repository->save($product); $event = new Product\Event\ProductPriceUpdated( (int) $product->id(), (double) $oldPrice, (double) $newPrice ); $this->eventBus->dispatch($event); } }

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Robert Bašić ~ PHPSrbija #29 An event is always valid productId = $productId; $this->oldPrice = $oldPrice; $this->newPrice = $newPrice; } public function productId() { return $this->productId; } public function oldPrice() { return $this->oldPrice; } public function newPrice() { return $this->newPrice; } }

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Robert Bašić ~ PHPSrbija #29 Event listeners oldPrice() <= $event->newPrice()) { return; } $product = $this→repository→get($productId); $command = new Product\Command\SendPriceDecreaseEmail($product); $this->commandBus->dispatch($command); } }

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Robert Bašić ~ PHPSrbija #29 Event buses in PHP

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Robert Bašić ~ PHPSrbija #29 Event buses in PHP ● SimpleBus, Prooph Service Bus

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Robert Bašić ~ PHPSrbija #29 Event buses in PHP ● SimpleBus, Prooph Service Bus ● Differ in creation and configuration

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Robert Bašić ~ PHPSrbija #29 Event buses in PHP ● SimpleBus, Prooph Service Bus ● Differ in creation and configuration ● Similar usage

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Robert Bašić ~ PHPSrbija #29 Event buses in PHP ● SimpleBus, Prooph Service Bus ● Differ in creation and configuration ● Similar usage ● Plugins, middlewares

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Robert Bašić ~ PHPSrbija #29 Query Bus

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Robert Bašić ~ PHPSrbija #29 Query Bus

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Robert Bašić ~ PHPSrbija #29 Queries

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Robert Bašić ~ PHPSrbija #29 Queries ● Not the same as database queries

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Robert Bašić ~ PHPSrbija #29 Queries ● Not the same as database queries ● A query is a question

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Robert Bašić ~ PHPSrbija #29 Queries ● Not the same as database queries ● A query is a question ● LatestProductsCreated, ProductsOnSale

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Robert Bašić ~ PHPSrbija #29 Queries ● Not the same as database queries ● A query is a question ● LatestProductsCreated, ProductsOnSale ● Answers from read models

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Robert Bašić ~ PHPSrbija #29 Dispatching queries get('from'), $request->get('to') ); $products = $this->queryBus->dispatch($query); // pass $products to template for displaying ... } }

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Robert Bašić ~ PHPSrbija #29 A query is always valid from = new \DateTimeImmutable($from); $this->to = new \DatetTimeImmutable($to); } public function from(): \DatetTimeImmutable { return $this->from; } public function to(): \DatetTimeImmutable { return $this->to; } }

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Robert Bašić ~ PHPSrbija #29 Query handlers productsBoughtReadModel->fetch($query->from(), $query->to()); } }

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Robert Bašić ~ PHPSrbija #29 Query buses in PHP

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Robert Bašić ~ PHPSrbija #29 Query buses in PHP ● Prooph Service Bus

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Robert Bašić ~ PHPSrbija #29 Query buses in PHP ● Prooph Service Bus ● Plugins

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Robert Bašić ~ PHPSrbija #29 Ready for the next project!

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Robert Bašić ~ PHPSrbija #29 Resources ● CQRS Documents by Greg Young ● SimpleBus by Matthias Noback ● Prooph series by Robert Basic ● perfi by Robert Basic

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Robert Bašić ~ PHPSrbija #29 Q&A Robert Bašić https://robertbasic.com/ @robertbasic

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Robert Bašić ~ PHPSrbija #29 Images used ● http://www.globalgeeknews.com/2011/12/22/the-life-of-a-so ftware-engineer-comic/