Engineering With Java: Digest #59

Clean exception handling, API throttling without external libs, monolith vs microservices decision-making for 2025, and zero-trust OAuth2/JWT security in Spring Boot and more ...

Welcome to this week’s edition! I hope you all had a great, productive week. We have summarized this week’s Java and Spring Boot update in a 5-minute summary.

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📝 Articles Of The Week (8)

• Clean Exception Handling in Java: A Framework-Agnostic Approach to Maintainable Error Flow - Presents a framework-agnostic way to handle Java exceptions by using a clear, domain-specific hierarchy, functional patterns like Either, and centralized error mapping to ensure consistent, maintainable error flows.

• How to Build an MCP Server With Java SDK - Guides building a Modular Control Plane (MCP) server in Java using an SDK for dynamic resource management and modular design.Focuses on clean architecture, lifecycle handling, and exposing APIs for scalable distributed systems.

• API Throttling Logic in Spring Boot Without External Libraries - Explains & demonstrates how to implement API throttling directly in Spring Boot without relying on external libraries by using request interceptors and in-memory counters.

• 🧱 Monolith or 🧩 Microservices in 2025? - Compares monolith and microservices architectures in 2025, highlighting that while microservices offer scalability and flexibility, monoliths remain simpler to develop and maintain for many use cases.
  Suggests a balanced, pragmatic approach—choosing the right architecture based on team size, project complexity, and long-term goals rather than blindly favoring microservices.

• Zero-Trust API Access with OAuth2 & JWT in Spring Boot - Configure Spring Boot as an OAuth2 Resource Server to validate JWTs issued by an external authorization server. Enforce role-based access, customize JWT claim-to-role mapping, and support stateless, scalable authentication—all while keeping development friction low.

• Optimizing JSON Performance in Java: What Actually Works - Advises against using the outdated org.json library due to poor performance and lack of thread safety. Recommends faster, production-ready options like Jackson, Gson, or Jsoniter, with proper tuning for maximum speed.

• A Practical Guide to Null-Safety in Java With JSpecify - Article explains JSpecify, a Java community-driven effort to standardize nullness annotations for better null-safety in Java code. Covers how JSpecify annotations help tools detect potential null pointer exceptions early by making null contracts explicit without being tied to a single framework.

• Inline Images in Email Using Java Mail - Send emails with inline images using JavaMail by embedding images as MIME body parts with Content-ID references. Enables embedding pictures directly inside the email content, enhancing visual appeal without requiring recipients to download attachments separately.

💬 Social Media Posts Of The Week (3)

• Kyle shares a distributed systems reliability glossary - a curated reference designed for developers and engineers to deepen their understanding of reliability concepts in distributed systems.

• Gunnar talks about the importance of enabling query logging in Hibernate during development.

• Roman shares about elegantly restricting access to REST controllers in Spring Boot using @PreAuthorize and Spring Expression Language (SpEL) — no messy manual permission checks in the controller!

▶️ Videos Of The Week

• Java Techie teaches how to build resilient, fault-tolerant workflows in Spring Boot using Temporal with retries, timeouts, and failure recovery.

• Simplilearn offers a 9-hour Core Java tutorial for beginners.

• Sergey Chernov shares how their platform team optimized Spring-based integration tests across a massive monolith and 200+ microservices.
  He dives into memory, container lifecycle, and context reuse challenges, offering practical strategies to reduce flakiness, resource usage, and CI overhead at scale.

🛠️ Code & Tools Of The Week

• Modelmapper is a Java object mapping library that simplifies converting one object to another, especially when dealing with DTOs (Data Transfer Objects) and entity objects in layered architectures.

• Spotlees is a versatile code formatting and linting tool built for a wide variety of languages and build systems.

🧑🏻‍💻 Interview Prep

• Some mid-level interview/coding questions ( this newsletter )

• Evergreen list of Theoretical Java Interview Questions

  • DevInterview

  • DataCamp

• Beginner-level coding questions

📚 Books Of The Week

• 50 Java Concepts Every Developer Should Know

• Baeldung All Access - (Lifetime) | Learn Spring/Spring Data JPA/ Spring REST /Junit

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