https://gurkanucar.com/ Recent content on Gürkan UÇAR Hugo en-US Sun, 09 Aug 2026 12:00:00 +0300 https://gurkanucar.com/posts/clean-architecture-adapter-and-strategy-spring-boot/ Sat, 08 Aug 2026 10:00:00 +0300 https://gurkanucar.com/posts/clean-architecture-adapter-and-strategy-spring-boot/ Two different external companies, two incompatible APIs, one domain model. The Adapter pattern gives them a common language in Spring Boot, while Strategy decides which one should run: at startup with @ConditionalOnProperty or per request with a factory. https://gurkanucar.com/posts/clean-code-guard-clauses-early-return/ Sat, 08 Aug 2026 10:00:00 +0300 https://gurkanucar.com/posts/clean-code-guard-clauses-early-return/ How to turn nested if-else blocks into readable code with guard clauses and early return, shown on a real airline check-in scenario. https://gurkanucar.com/posts/kafka-vs-rabbitmq/ Sun, 09 Aug 2026 12:00:00 +0300 https://gurkanucar.com/posts/kafka-vs-rabbitmq/ The differences between Kafka and RabbitMQ, starting from what happens to a message inside the broker; then the same scenario built on both, to make &#39;why this one, and what would have happened with the other&#39; concrete. https://gurkanucar.com/posts/async-email-sending-system-design/ Sat, 08 Aug 2026 10:00:00 +0300 https://gurkanucar.com/posts/async-email-sending-system-design/ How to design an async email system that does not tie your workflow to the provider, while handling duplicate sends and silent losses: atomic enqueue, idempotent claim, stuck-job recovery, retry and retention. https://gurkanucar.com/posts/chain-of-responsibility-spring-boot/ Sat, 08 Aug 2026 10:00:00 +0300 https://gurkanucar.com/posts/chain-of-responsibility-spring-boot/ Instead of managing many business rules in one service, use Chain of Responsibility and a pipeline to make the rules independent, testable and easy to extend. https://gurkanucar.com/posts/facade-pattern-spring-boot/ Sat, 08 Aug 2026 10:00:00 +0300 https://gurkanucar.com/posts/facade-pattern-spring-boot/ Instead of dealing with payment, ticketing, baggage, notification and loyalty systems one by one in a booking flow, the Facade Pattern puts the whole workflow behind a single interface. https://gurkanucar.com/posts/mediator-pattern-react-zustand-checkout/ Sat, 08 Aug 2026 10:00:00 +0300 https://gurkanucar.com/posts/mediator-pattern-react-zustand-checkout/ In React, components that keep affecting each other get messy fast — prop drilling and long callback chains. Let&#39;s see how to keep all that coordination in one place with the Mediator Pattern and Zustand. https://gurkanucar.com/posts/n-plus-one-query-jpa-hibernate-spring-boot/ Sat, 08 Aug 2026 10:00:00 +0300 https://gurkanucar.com/posts/n-plus-one-query-jpa-hibernate-spring-boot/ Running hundreds of SQL queries without noticing it: why the N+1 problem happens, and how to fix it in Spring Boot and JPA with JOIN FETCH, EntityGraph, batch fetching and DTO projection. https://gurkanucar.com/about/ Thu, 06 Aug 2026 00:00:00 +0000 https://gurkanucar.com/about/ <img src="https://gurkanucar.com/images/gurkan-ucar_hu_3f8793ec2194bd09.webp" srcset="https://gurkanucar.com/images/gurkan-ucar_hu_3f8793ec2194bd09.webp 300w" sizes="132px" width="300" height="300" alt="Gürkan UÇAR" loading="eager" decoding="async" class="about-portrait"> <p>I&rsquo;m a Software Engineer with a strong background in Java development. I started programming in high school and now work at <strong>Turkish Airlines Technology</strong>.</p> <p>My skills include Spring Boot, MongoDB, PostgreSQL, Kafka, Redis, and Websocket for real-time communications.</p> https://gurkanucar.com/posts/markdown-and-shortcodes/ Wed, 01 Jan 2020 09:00:00 +0300 https://gurkanucar.com/posts/markdown-and-shortcodes/ A working reference for every formatting feature, shortcode and embed available on this site — callouts, tabs, steps, diagrams, maths, terminal recordings and the plain markdown underneath it all.