Blog

Mert Özen's blog posts on software development, backend, frontend, and DevOps.

Series

.NET Core Web API 36 Angular 31 JavaScript Basics 19 JavaScript Intermediate 18 JavaScript Advanced 16 TypeScript Basics 14 TypeScript Intermediate 14 TypeScript Advanced 12 Entity Framework Core 28 Dapper 16 Git & GitHub 29 Web Security (OWASP Top 10) 21 LLM Fundamentals 20 C# Fundamentals 20 Object-Oriented Programming in C# 16 C# Collections and Generics 11 LINQ 17 Asynchronous Programming in C# 17 Advanced C# 14 C# Versions 6 Solution Patterns 22 SOLID and Design Principles 12 Clean Code 13 Design Patterns 23 UML and Modeling 18 Introduction to Software Architecture 9 Clean, Onion and Hexagonal Architecture 8

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Software Design PART 11

State Machine Diagrams: States, Transitions, Guards, Entry/Exit and Turning the Leave Request Lifecycle into Code

A state machine diagram shows which states an object can be in and which event, under which guard, moves it where; every arrow becomes a switch arm, a Stateless PermitIf and a unit test. In this post we draw the leave request lifecycle with a composite state, a choice and the entry/effect distinction, and turn it into C# and tests.

7 Nov 2026 16 min 3

Software Design PART 18

End-to-End Modeling: Taking the Leave Module from Requirements to Working Code

Diagrams pay off when they form a traceable chain from requirement to endpoint, from state machine to domain code and from ER to migration, and when they answer "which diagram changes?" before a change is made. In the series finale we take the leave module to .NET 10 API, EF Core and Angular 22 code, measure the impact of a half-day leave requirement with git diff and show the real bugs the diagrams caught along the way.

7 Nov 2026 17 min 4