--- title: "Design Patterns" description: "Backbone and Design Patterns" type: "docs" category: "doc" tags: [] authors: [Anonymous] date: "2026-09-09" last_update: "2026-09-09" time_minutes: 6 draft: false unlisted: false url: "https://www.derafu.dev/docs/core/backbone/design-patterns" --- # Backbone and Design Patterns This document explores how Derafu Backbone implements and leverages established design patterns to create a robust, maintainable architecture for PHP applications. {.w-50 .mx-auto} ![Design Patterns](https://www.derafu.dev/img/diagrams/content/docs/core/backbone/derafu-backbone-design-patterns.svg) ## Design Patterns in Backbone Derafu Backbone draws inspiration from several well-established design patterns. Understanding these patterns and their implementation in Backbone helps developers use the framework effectively and extend it appropriately. ## Jobs and the Command Pattern Jobs in Backbone are a direct implementation of the Command Pattern. ### Command Pattern Overview The Command Pattern encapsulates a request as an object, allowing: - Parameterization of clients with different requests. - Queueing of requests. - Logging of requests. - Support for undoable operations. ### How Jobs Implement Command Jobs in Backbone embody these principles: - Each job is a class that encapsulates a single operation. - Jobs have a standardized execution method (`execute()`). - Jobs can be parameterized through their execute method. - Jobs are self-contained and can be invoked by various clients. ```php #[Job(name: 'create', worker: 'generator', component: 'invoice', package: 'billing')] class CreateInvoiceJob extends AbstractJob implements JobInterface { public function execute(array $data): Invoice { // Validate input. $this->validateInput($data); // Create invoice $invoice = new Invoice(); $invoice->setCustomer($data['customer']); $invoice->setItems($data['items']); // Return result. return $invoice; } private function validateInput(array $data): void { // Validation logic. } } ``` ### Benefits of the Command Pattern in Jobs This implementation provides several advantages: - **Single Responsibility**: Each job has a clear, specific purpose. - **Reusability**: Jobs can be reused in different contexts. - **Testability**: Jobs are easy to test in isolation. - **Extensibility**: New jobs can be added without modifying existing code. - **Queueability**: Jobs can be serialized and queued for asynchronous processing. ## Handlers and the Mediator/Chain of Responsibility Patterns Handlers in Backbone combine aspects of both the Mediator and Chain of Responsibility patterns. ### Mediator Pattern Overview The Mediator Pattern defines an object that encapsulates how a set of objects interact, promoting loose coupling by preventing objects from referring to each other explicitly. ### Chain of Responsibility Overview The Chain of Responsibility Pattern passes a request along a chain of handlers, with each handler deciding either to process the request or pass it to the next handler. ### How Handlers Implement These Patterns Handlers in Backbone combine these concepts: - They coordinate interactions between multiple Jobs (Mediator). - They orchestrate a sequence of operations (Chain of Responsibility). - They encapsulate complex workflows. ```php #[Handler(name: 'process', worker: 'processor', component: 'invoice', package: 'billing')] class ProcessInvoiceHandler extends AbstractHandler implements HandlerInterface { public function handle(Invoice $invoice, array $options = []): Result { // Validate the invoice. $validationResult = $this->getJob('validate')->execute($invoice); if (!$validationResult->isValid()) { return Result::failure($validationResult->getErrors()); } // Determine processing strategy. $strategyName = $options['strategy'] ?? 'default'; $strategy = $this->getStrategy($strategyName); // Process the invoice. $processingResult = $strategy->process($invoice); if (!$processingResult->isSuccessful()) { return Result::failure($processingResult->getErrors()); } // Send notifications. $this->getJob('notify')->execute($invoice, $options['notifications'] ?? []); // Return success. return Result::success(['invoice' => $invoice, 'processed' => true]); } } ``` ### Benefits of These Patterns in Handlers This implementation provides several advantages: - **Decoupling**: Components don't need to know about each other. - **Centralized Control**: Complex workflows are managed in a single place. - **Flexibility**: Processing steps can be changed without affecting clients. - **Transactional Boundaries**: Handlers can manage transactions across multiple operations. - **Error Handling**: Centralized error handling for multi-step processes. ## Strategies and the Strategy Pattern Strategies in Backbone are a direct implementation of the Strategy Pattern. ### Strategy Pattern Overview The Strategy Pattern defines a family of algorithms, encapsulates each one, and makes them interchangeable. It lets the algorithm vary independently from clients that use it. ### How Strategies Implement the Pattern Strategies in Backbone embody these principles: - They provide alternative implementations of an algorithm. - They share a common interface. - They can be selected and switched at runtime. ```php #[Strategy(name: 'pdf', worker: 'renderer', component: 'document', package: 'billing')] class PdfRenderStrategy extends AbstractStrategy implements RenderStrategyInterface { public function render(Document $document): string { // PDF rendering implementation. return $this->pdfRenderer->renderDocument($document); } } #[Strategy(name: 'html', worker: 'renderer', component: 'document', package: 'billing')] class HtmlRenderStrategy extends AbstractStrategy implements RenderStrategyInterface { public function render(Document $document): string { // HTML rendering implementation. return $this->htmlRenderer->renderDocument($document); } } ``` ### Benefits of the Strategy Pattern This implementation provides several advantages: - **Encapsulation**: Different algorithms are encapsulated in separate classes. - **Interchangeability**: Strategies can be swapped without changing client code. - **Elimination of Conditionals**: Complex conditional logic is replaced with polymorphism. - **Runtime Selection**: Algorithms can be selected based on runtime conditions. - **Testability**: Each strategy can be tested independently. ## Workers and the Facade Pattern Workers in Backbone implement the Facade Pattern. ### Facade Pattern Overview The Facade Pattern provides a unified interface to a set of interfaces in a subsystem. It defines a higher-level interface that makes the subsystem easier to use. ### How Workers Implement the Facade Workers in Backbone act as facades: - They provide a simplified interface to complex subsystems. - They handle the complexity of coordinating jobs, handlers, and strategies. - They expose domain operations through a clean API. ```php #[Worker(name: 'processor', component: 'invoice', package: 'billing')] class InvoiceProcessorWorker extends AbstractWorker implements WorkerInterface { // This method is part of the public API. public function processInvoice(Invoice $invoice, array $options = []): Result { // Delegate to the appropriate handler. return $this->getHandler('process')->handle($invoice, $options); } // Another public API method. public function validateInvoice(Invoice $invoice): ValidationResult { // Delegate to a job. return $this->getJob('validate')->execute($invoice); } } ``` ### Benefits of the Facade Pattern in Workers This implementation provides several advantages: - **Simplified Interface**: Clients interact with a clean, focused API. - **Reduced Coupling**: Clients don't need to know about the subsystem's components. - **Unified Entry Point**: Workers provide a single entry point to related functionality. - **Abstraction**: Implementation details are hidden behind the facade. ## Hexagonal Architecture Influence The overall architecture of Backbone is inspired by Hexagonal Architecture (also known as Ports and Adapters). ### Hexagonal Architecture Overview Hexagonal Architecture aims to create loosely coupled application components that can be easily connected to their software environment by means of ports and adapters. ### How Backbone Implements Hexagonal Concepts Backbone incorporates these principles: - **Domain-Centric**: The architecture focuses on domain logic. - **Ports**: Interfaces define how components interact. - **Adapters**: Implementations connect the domain to external systems. - **Inversion of Control**: Dependencies point inward toward the domain. The Package-Component-Worker structure creates clear boundaries within the domain, while Strategies often serve as adapters to external systems. ## Practical Application When applying these design patterns in your Backbone applications: 1. **Identify the Pattern**: Recognize which pattern applies to your situation. 2. **Follow the Template**: Use the appropriate Backbone component. 3. **Respect the Boundaries**: Maintain separation between different components. 4. **Leverage Polymorphism**: Use strategies for variant implementations. 5. **Focus on Composition**: Prefer composition over inheritance. By understanding and applying these design patterns within Backbone, you can create well-structured, maintainable applications that are flexible enough to adapt to changing requirements. --- Last updated on 09/09/2026