Topic archive
Spring Boot
Spring Boot, JPA, transaction management, and backend practices.
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Server-Sent Events with Spring Boot WebFlux: A Tested Implementation and Its Limits
A Spring WebFlux SSE endpoint built with Reactor Sinks, verified in Chrome: named events, automatic reconnection, Last-Event-ID replay, and the sink behaviors that break shared streams.
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Spring Boot GraphQL with Spring for GraphQL: Batch Loading, Error Shapes, and the Three Security Mistakes That Compile
A tested Spring Boot 3.5.16 bookstore API: measured N+1 with @SchemaMapping vs @BatchMapping, what validation errors actually look like to a client, and why @PreAuthorize on a controller can be doing nothing at all.
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Streaming File Uploads in Spring Boot: 300 MB Under a 64 MB Heap, Measured in WebFlux and MVC
What a multipart upload actually does in Spring Boot 3.5.16: when the handler runs relative to the bytes on the wire, why a size check inside FilePart.content() cannot abort early, why the usual per-buffer APPEND write fails outright, and 300 MB uploads under -Xmx64m in both stacks.
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Spring Boot 3 Cache Invalidation with Redis: @CacheEvict, @CachePut, TTL, Null Entries, and What Pub/Sub Is Actually For
Tested on Spring Boot 3.5.16 and Redis 7.4.11: the exact keys and TTLs Spring writes, why a null result can throw, why a second instance needs no pub/sub message to see an eviction, and the customizer ordering trap behind spring.cache.cache-names.
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Spring Boot 3.5 Native Images with GraalVM: A Measured Build, Startup Against the JVM, and a Reflection Failure Fixed with RuntimeHints
One Spring Boot 3.5.16 web app compiled with GraalVM CE 21.0.2 and Native Build Tools 0.10.6: 1m14s build, 78 MB binary, first response in about 50 ms versus about 1 s on the JVM, plus a ClassNotFoundException reproduced in the native binary and fixed with a RuntimeHintsRegistrar.
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Implementing Idempotent REST APIs in Spring Boot for Reliable Production Operations
This detailed guide explains how to build truly idempotent POST REST APIs using Spring Boot 3, covering idempotency keys, concurrency handling, persistent caching, and verification.
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Building a Feature Toggle System in Spring Boot for Safe Production Deployments
Build a dynamic, secure, and performant feature toggle system in Spring Boot using database persistence and caching with runtime REST API management and practical usage examples.
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Custom Metrics in Spring Boot 3.5 with Micrometer and Prometheus: Names, Exposure, Cardinality, and the Test That Returns 404
A Spring Boot 3.5.16 counter, gauge, and timer scraped by a real Prometheus 3.14, with the naming rules, the exposure property, a measured user-id cardinality blow-up and its MeterFilter cap, and the @AutoConfigureObservability trap in tests.
