Spring WebFlux Training in Dhaka, Bangladesh

This hands-on training introduces participants to reactive programming and the Spring WebFlux framework using only open-source tools. The program begins with foundational concepts of reactive systems, explores how Spring WebFlux enables scalable non-blocking applications, and then guides participants through building fully functional reactive REST APIs. Through labs and a small end-to-end project, learners gain practical experience with WebFlux, Project Reactor, reactive data access using R2DBC/MongoDB, and WebClient-based integrations. The goal is to enable developers to confidently design, build, test, and deploy reactive microservices.

Foundations of Reactive Programming & WebFlux

1. Introduction to Reactive Programming

• What is reactive programming?
• Reactive Streams Specification
• Key concepts: Publisher, Subscriber, Subscription, Backpressure
• When to use reactive systems

2. Tools Setup

• JDK 17+
• Maven or Gradle
• VS Code or IntelliJ IDEA Community Edition
• Postman
• Docker (optional)
• Git + GitHub/GitLab

3. Introduction to Spring WebFlux

• Difference: Spring MVC vs Spring WebFlux
• Netty server architecture
• Mono & Flux (from Project Reactor)

4. Hands-On Labs

Building Reactive APIs & Data Access

1. Reactive Controllers

• Functional endpoints vs annotated controllers
• Creating CRUD endpoints using WebFlux

2. Reactive Data Access

• Reactive repositories
• Connection factories
• Creating entities & repositories
• CRUD operations using reactive DB

3. Error Handling & Validation

• WebExceptionHandler
• Global error handling pattern
• Bean validation with reactive controllers

4. Hands-On Labs

Advanced Concepts & End-to-End Integration

1. WebClient & Reactive Inter-service Communication

• Using WebClient to call external APIs
• Handling backpressure and timeouts
• Retries & fallbacks (Reactor Retry)

2. Reactive Streams Processing

• Transformations (map, flatMap, filter, reduce)
• Combining publishers: zip, merge, concat
• Handling large streams

3. Testing Reactive Services

• JUnit 5 + Reactor Test
• Testing WebClient
• WebTestClient for end-to-end testing

4. Observability & Performance Basics

• Reactor debug mode
• Logging operators
• Basic performance tips (thread model, event loop)

5. Hands-On Exercises