Engineering With Java: Digest #65
This week’s highlights feature Spring Framework 7/Boot 4 updates, modern Java adoption, cloud-native API tutorials, and tools like Scoped Values, OpenTelemetry, TOON, Spring Data AOT, and LocalStack.
Editors Note
Welcome to this week’s edition! I hope you all are doing great. I was on a long break to my home country, so I couldn’t post the newsletter for a while. Now I am back and ready to publish more Java and Spring Boot-related content.
This week’s highlights cover major Java and Spring updates, including Spring Framework 7 and Boot 4 with API versioning, null-safety, and resilience features, plus modern Java adoption. Key tutorials focus on memory leak troubleshooting, cloud-native Quarkus APIs on AWS, Micrometer metrics with Kafka, and Spring AI object mapping. Tools and libraries featured include Scoped Values, OpenTelemetry integration, TOON serialization, Spring Data AOT, and LocalStack for local AWS service emulation.
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📝 Articles Of The Week (8)
Spring Framework 7 and Spring Boot 4 Deliver API Versioning, Resilience, and Null-Safe Annotations: Spring Framework 7 and Spring Boot 4 modernize the ecosystem with API versioning, JSpecify-based null-safety, and built-in resilience patterns. Spring Boot 4 upgrades core libraries like Jackson 3 and introduces modular auto-configuration for faster startup and clearer structure. The platform now targets Java 25, Jakarta EE 11, and Kotlin 2.2, raising type safety and overall developer experience.
From Symptoms to Solutions: Troubleshooting Java Memory Leaks and OutOfMemoryError: Java memory leaks can be detected by watching for steadily rising heap usage, frequent GC activity, and performance degradation before an OOM occurs. Diagnosing leaks involves capturing and analyzing heap dumps to pinpoint objects that continue growing unexpectedly. Tools like HeapHero help identify root causes using dominator trees, class histograms, and reference paths.
Building a Containerized Quarkus API on AWS ECS/Fargate With CDK: A Quarkus API can be built in a clean, layered architecture that separates presentation, application, and data logic. The solution integrates PostgreSQL and Redis while using AWS CDK to define VPCs, ECS clusters, Fargate services, and autoscaling as infrastructure-as-code. The result is a modular, cloud-native setup with strong configuration management, caching, and transaction reliability.
Micrometer & Prometheus in Spring Boot: Kafka Burger Orders: Shows how to integrate Micrometer and Prometheus into a Spring Boot app that handles burger orders via Kafka. We can POST a burger order (e.g., “DukeBurger”) to a REST endpoint, which is then published to a Kafka topic and consumed by a listener. For each “DukeBurger” order, a Micrometer counter (
events_DukeBurger_total) increments. Metrics are exposed at/actuator/prometheusfor Prometheus to scrape.Service Layer Pattern in Java With Spring Boot: The service layer pattern places business logic in dedicated service classes between controllers and repositories. This keeps controllers lightweight while services enforce rules, coordinate operations, and manage workflows. The result is cleaner architecture with better maintainability, easier testing, and flexibility to change underlying data infrastructure.
Spring AI: Mapping LLM Responses to Java Objects: Spring AI maps LLM responses into Java objects via structured JSON, using classes or records to generate schemas. Responses are converted to the desired type, with customization via Jackson annotations and support for collections. This enables type-safe handling, though validation is needed since model outputs may be correct in format but inaccurate in content.
Scoped Values: The Modern Alternative to ThreadLocal That Java Developers Have Been Waiting For: Scoped Values in Java offer a safer alternative to ThreadLocal, providing immutable, scope-bound context visible only within a defined block and its child scopes. They prevent common ThreadLocal issues like memory leaks and mutable state, automatically cleaning up after use. Optimized for high-concurrency, they work efficiently with virtual threads and Project Loom
OpenTelemetry with Spring Boot: Explains integrating OpenTelemetry with Spring Boot to capture metrics, traces, and logs via OTLP. It covers using the Java Agent, third-party starter, or official spring-boot-starter-opentelemetry, bridging Micrometer metrics and tracing. Context propagation across threads is handled with a ContextPropagatingTaskDecorator, while OTLP log export requires manual Logback or Log4j2 configuration.
▶️ Videos Of The Week (3)
Deep Dive into Gatherers - JEP Cafe #24: The Gatherer API adds a powerful way to create custom intermediate Stream operations that go beyond what map, filter, or flatMap can do. It introduces concepts like integrators, downstream control, mutable state, and stream interruption. It’s flexible but complex—use it only when simpler Stream patterns don’t work.
Off-CPU Profiling & Latency Diagnostics in Java: The speaker shares JVM engineering experience at Alibaba Cloud, emphasizing GC, performance, and custom JDKs like Dragonwell and AJDK. They highlight off-CPU profiling, showing latency often stems from scheduling and I/O rather than GC. The team focuses on cross-platform diagnostics and detailed latency analysis to identify and resolve performance bottlenecks.
Spring Framework 7 is released! 5 things you should learn NOW!: Spring Framework 7 brings built-in resilience patterns, API versioning, and null-safety annotations, highlighting priorities for enterprise Java in the next 3–5 years. It requires Java 17+ and leverages newer JDK features, signaling a shift toward modern concurrency, syntax, and tooling. Teams not yet upgrading should still learn resiliency, API evolution, and modern Java, as these are becoming baseline expectations.
Social Media Posts Of The Week (2)
This post talks about Spring Data AOT moves query parsing to compile time, giving 50–70% faster startup, build-time typo detection, pre-generated SQL, and native-image readiness. New in Spring Data 2025 + Spring Boot 4.
This post talks about LocalStack, which lets you run AWS services like Lambda, S3, and DynamoDB locally in a Docker container—no AWS account or costs needed. The community edition supports most core services, enough for learning and basic workflows.
🛠️ Code & Tools Of The Week (1)
toon-java (JToon) is a Java library that implements the TOON serialization format—a compact, LLM-friendly alternative to JSON. It provides simple encode/decode APIs, supports custom indentation and delimiters, and aims to reduce token usage by ~30–60%. The project is Java 17-based, MIT-licensed, and still in beta, so the spec and APIs may evolve
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It's interesting how Spring 7 and Boot 4 modernize everything. Thanks for the insights, truly wonderfull!