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The article explains how to integrate multiple bounded contexts in a payroll system by using four DDD‑based relationship patterns—Shared Kernel, Customer‑Supplier, Anti‑Corruption Layer, and Open Host Service—detailing their motivations, code organization, risks, and selection criteria.
The article explains how bounded contexts, defined by language boundaries rather than functional ones, guide the logical separation of a payroll system into distinct domains, illustrating the process with concrete terminology lists, ambiguity detection, authority mapping, code examples, and deployment‑agnostic module structures.
The article shows how mismatched business and code vocabularies cause confusion, then guides readers through building a shared glossary, renaming domain objects and types in Java, and enforcing the conventions with a code‑review checklist to keep the ubiquitous language alive in the codebase.
The article explains why traditional three‑layer architectures let business logic bloat inside services, demonstrates the pitfalls of anemic domain models with a 7,000‑line SalaryService example, and shows how DDD’s rich domain model restores rule ownership and maintainability.
The article explains how the Template Method pattern pervades Spring’s core classes—such as JdbcTemplate, AbstractApplicationContext, and various *Template classes—by fixing the overall algorithm flow while delegating the variable steps to subclasses, and contrasts it with the Strategy pattern.
The article examines the evolution of six singleton implementations in Java, explains why the double‑checked locking pattern requires the volatile keyword to prevent instruction reordering bugs, compares Spring container‑managed singletons with classic GoF singletons, and highlights common pitfalls such as mutable state in singleton beans.
This article walks through the three core behavioral design patterns—Strategy, Observer, and Chain of Responsibility—explaining their intent, showing problematic anti‑patterns, providing step‑by‑step Spring and MQ code implementations, mapping them to real‑world frameworks, and offering interview‑style comparison questions to solidify understanding.
This article explains the four essential structural design patterns—Proxy, Decorator, Adapter, and Facade—detailing their core concepts, real‑world Java/Spring use cases, code implementations, and interview‑focused comparisons to help developers master enterprise‑level architecture.
This article explains why telescoping constructors and JavaBean setters are problematic, demonstrates a hand‑written Builder implementation based on Effective Java, shows how Lombok @Builder simplifies code, and warns about two common Lombok pitfalls—default values and inheritance—while offering practical solutions.
Learn how to replace sprawling if‑else logic in payment gateways and SaaS platforms by combining the Strategy and Factory patterns, with concrete Spring Boot examples, step‑by‑step code, and a progression from simple to abstract factories that enforce the Open‑Closed principle.
