Dependency Injection in Web API (Services & Lifetimes)

Key Topics Covered

• Introduction to DI
• benefits of decoupling & testability
• service lifetimes (Singleton, Scoped, Transient)
• real request-based lifetime behavior

Hands-On Lab / Demo

Live demo showing lifetime differences across requests

Repository Pattern for Web API

Key Topics Covered

• Repository pattern concept
• clean controller design
• IRepository & Repository structure
• Service layer (optional)
• DbContext lifetime (Scoped)
• DI request lifecycle

Hands-On Lab / Demo

Build Repository → Service → Controller flow

Applying DI Lifetimes in Real-World Apps|

Key Topics Covered

• Choosing lifetimes correctly
• Transient for utilities
• Singleton for shared configuration/cache services
• lifetime rules & best practices

Hands-On Lab / Demo

TaxCalculationService (Transient) & Settings service (Singleton) demos

EF Core Integration & CRUD Operations

Key Topics Covered

• EF Core overview
• DbContext & DbSet
• POST/PUT/DELETE APIs
• clean architecture flow
• basic error handling

Hands-On Lab / Demo

Full CRUD API with EF Core & Postman testing

Paging, Sorting & Filtering in APIs

Key Topics Covered

• Filtering with query params & LINQ
• sorting (ASC/DESC)
• pagination using Skip/Take
• edge cases

Hands-On Lab / Demo

Build final GET API with filter + sort + pagination

AutoMapper for APIs (Entity ⇆ DTO)

Key Topics Covered

• DTO importance
• request vs response DTOs
• AutoMapper concepts
• manual vs auto mapping
• performance considerations

Hands-On Lab / Demo

AutoMapper configuration & DTO-based APIs

N-Tier Architecture for Web APIs

Key Topics Covered

• Layered architecture concept
• API/Application/Domain/Infrastructure layers
• moving from simple repo to full architecture

Hands-On Lab / Demo

Refactor existing API into N-Tier structure

Asynchronous APIs & Performance

Key Topics Covered

• Why async is needed
• thread blocking issues
• async/await behavior
• TAP model
• scalability concepts

Hands-On Lab / Demo

Convert sync APIs to async & observe behavior

File Upload & Download in Web APIs

Key Topics Covered

• IWebHostEnvironment
• IFormFile
• multipart/form-data
• file validation
• upload & download strategies

Hands-On Lab / Demo

File upload & download APIs using FileStream

Rate Limiting in ASP.NET Core Web API

Key Topics Covered

• What is rate limiting
• why APIs need limits
• real-world use cases (login, OTP, banking APIs)
• IP vs client-based limiting
• time windows & thresholds
• HTTP 429 handling
• best practices for secure APIs

Hands-On Lab / Demo

Configure rate limiting using NuGet, appsettings.json, middleware & test controller

JWT Authentication in ASP.NET Core Web APIs

Key Topics Covered

• Authentication vs authorization
• JWT structure (Header/Payload/Signature)
• JWT real-world usage
• appsettings JWT configuration
• issuer/audience/secret key
• token expiration & claims

Hands-On Lab / Demo

Implement JWT authentication, create login API, generate token & test via Postman

OAuth 2.0 Authentication in ASP.NET Core Web API

Key Topics Covered

• OAuth 2.0 & OpenID Connect concepts
• roles & authorization flow
• access token vs ID token
• Google OAuth endpoints
• scopes & token decoding

Hands-On Lab / Demo

Google OAuth setup, app registration, OAuth login flow & JWT generation

Role & Policy-Based Authorization (JWT)

Key Topics Covered

• JWT recap
• claims vs roles vs policies
• adding role claims in JWT
• defining policies
• role-based vs policy-based authorization

Hands-On Lab / Demo

Secure APIs using [Authorize], Admin vs User access demo

CORS in Web APIs (Cross-Origin Resource Sharing)

Key Topics Covered

• Same-Origin Policy
• understanding CORS errors
• enabling CORS policies
• AllowAnyOrigin / Method / Credentials
• security implications

Hands-On Lab / Demo

Enable & test CORS using external HTML client

Global Exception Middleware in ASP.NET Core

Key Topics Covered

• Exceptions vs errors
• expected API scenarios (400, 409)
• drawbacks of try/catch in controllers
• middleware-based global handling
• RequestDelegate & pipeline flow

Hands-On Lab / Demo

Build global exception middleware & test standardized error responses

Input Validation using FluentValidation

Key Topics Covered

• Why validation doesn’t belong in controllers
• FluentValidation basics
• FluentValidationAutoValidation
• request pipeline behavior
• rule-based validation & custom messages

Hands-On Lab / Demo

Implement FluentValidation with real API request validation

Introduction to Minimal APIs

Key Topics Covered

• Motivation & evolution of Minimal APIs
• Controllers vs Minimal APIs
• Program.cs-only API model
• characteristics of Minimal APIs
• safe and recommended use cases
• scenarios where Minimal APIs should be avoided

Hands-On Lab / Demo

Build a Minimal API using in-memory data with Program.cs only

Parameter Binding & Request Handling in Minimal APIs

Key Topics Covered

• Lambda handlers (MapGet, MapPost, MapPut, MapDelete)
• request lifecycle in Minimal APIs
• convention-based parameter binding
• route, query, header & body parameters

Hands-On Lab / Demo

Implement endpoints with multiple parameter binding types

Dependency Injection in Minimal APIs

Key Topics Covered

• DI fundamentals recap
• Controllers vs Minimal APIs DI model
• registering services (Singleton/Scoped/Transient)
• injecting services into lambda handlers
• using built-in services (ILogger, IConfiguration)

Hands-On Lab / Demo

Register services and inject dependencies into Minimal API endpoints

Odata in ASP.NET Core

Key Topics Covered

• Introduction & Problem Statement (challenges with traditional/minimal APIs, multiple endpoints, maintenance issues)
• Introduction to OData (one endpoint per entity, OData query options)
• Core OData Concepts (request flow, EDM, metadata, key components)
• Hands-On Demo (Product model, EDM with ODataConventionModelBuilder, configuring OData, single endpoint, IQueryable)
• Live Query Demo (get all, filter, sort, paging, field selection, combine queries)

Introduction to GraphQL

Key Topics Covered

• Introduction to GraphQL and problem statement (over-fetching and under-fetching in REST)
• Core GraphQL concepts (Schema, Types, Queries, Mutations)
• Setting up GraphQL in ASP.NET Core
• Building GraphQL schema for Product and Order
• Single endpoint with multiple entities
• Live demo of querying multiple entities in one request
• Error handling and performance basics

gRPC basics

Key Topics Covered

• Introduction to gRPC and use cases
• Protocol Buffers (proto files) basics
• Unary vs Streaming calls
• Creating gRPC service in ASP.NET Core
• Defining messages and services
• Client-server communication demo
• Performance comparison with REST

REST vs Minimal APIs vs OData vs GraphQL vs gRPC

Key Topics Covered

• REST vs Minimal APIs vs OData vs GraphQL vs gRPC
• Architectural differences
• Performance comparison
• Payload size and network efficiency
• Use-case driven selection
• When to use which API style in real-world systems
• Designing hybrid API strategies