Middleware is software integrated into an app pipeline to manage requests and responses.

Chooses whether to pass the request to the next component in the pipeline.
Can perform work before and after the next component in the pipeline.
Request delegates are used to build the request pipeline. The request delegates handle each HTTP request.
Request delegates are configured using the Run, Map, and **Use **extension methods. We will go over it in detail later.
Each middleware component in the request pipeline is responsible for invoking the next component in the pipeline.

I will explain why we might need to use it, and in the following part of the series, we will go over how to use it in detail.

1. Authentication Middleware:

• Used to verify user identity. It can work with authentication systems like JWT, OAuth, or IdentityServer.

2. Authorization Middleware:

• Ensures that users have the proper permissions to access a specific resource.

3. Error Handling Middleware:

• Handles global exceptions, directs to custom error pages, or returns detailed or simplified response messages.

4. Routing Middleware:

• Determines how requests are routed to a specific endpoint (Controller or API).

5. CORS Middleware:

• Enables policies related to cross-origin requests, allowing requests from different domains.

6. Request Logging Middleware:

• Logs details of incoming requests and outgoing responses to help with performance tracking and debugging.

7. Response Compression Middleware:

• Compresses responses using techniques like gzip to reduce the size of the data sent to the client.

8. Session and Cookie Middleware:

• Manages sessions and cookies for storing data between multiple requests.

9. Caching Middleware:

• Improves performance by caching responses and serving them directly without reprocessing requests.

10. Localization Middleware:

• Supports multiple languages and formats based on the user's culture or language settings.

11. Response Headers Middleware:

• Modifies or adds specific HTTP headers in the response, like Cache-Control or X-Content-Type-Options.

12. Performance Monitoring Middleware:

• Analyzes the performance of requests and responses, such as the time taken for each request.

13. Security Policies Middleware:

• Adds security policies like HSTS (HTTP Strict Transport Security) and CSRF (Cross-Site Request Forgery) protection against web attacks.

14. WebSockets Middleware:

• Supports continuous connections using WebSockets for real-time applications such as chat apps.

15. Static Files Middleware:

• Serves static files such as images, CSS, and JavaScript files directly from the server without routing through the application layers.

16. API Rate Limiting Middleware:

• Controls the number of requests a user can send within a specific time to prevent abuse or attacks.

17. WebSocket Data Handling Middleware:

• Manages data sent over WebSocket channels directly, such as handling instant messages or data streams.

18. GraphQL Middleware:

• Handles GraphQL requests if you're using GraphQL instead of REST for your API.

19. GeoIP Middleware:

• Uses the user's IP address to determine their geographical location and customize the experience accordingly.

20. Redirection Middleware:

• Redirects users based on specific conditions, such as redirecting HTTP requests to HTTPS or redirecting to a specific page.

21. OAuth Middleware:

• Implements authentication and authorization using OAuth providers like Google or Facebook.

22. Telemetry Middleware:

• Gathers information about the performance and operations of the application for analysis and improvement.

23. Proxy Middleware:

• Forwards requests to another server (proxying), useful in microservices architectures.

24. A/B Testing Middleware:

• Directs a subset of users to different application paths to test user experiences.

25. Session Replay Middleware:

• Records and saves complete sessions for auditing or analysis purposes.

26. Bot Detection Middleware:

• Detects and blocks malicious bots trying to access the site.

27. Maintenance Mode Middleware:

• Puts the application in maintenance mode, displaying a specific message to users when the service is temporarily down.

28. Throttling Middleware:

• Controls the flow of data and requests in applications that need to regulate traffic for performance or security reasons.

29. IP Whitelisting Middleware:

• Allows only certain IP addresses to access the application or specific resources within the application.

30. Upload Handling Middleware:

• Manages file uploads in a customized manner, including verifying file types and sizes.

31. Debugging Middleware:

• Adds extra information to responses for debugging purposes, like environment or configuration data.

32. Metrics Middleware:

• Collects performance data such as response times and request counts, and integrates with monitoring systems like Prometheus or Grafana.

33. Custom Headers Middleware:

• Adds custom HTTP headers to requests or responses for specific purposes such as security or application identification.

34. Localization & Culture Middleware:

• Customizes the experience based on the user's culture or language system, including local currency, dates, and measurement systems.

35. Circuit Breaker Middleware:

• Adds mechanisms to isolate the system when certain issues are detected, allowing operations to pause until the service is restored.

36. GDPR Compliance Middleware:

• Manages policies related to personal data and compliance with data protection laws like GDPR.

37. External Services Middleware:

• Handles external API calls or manages communication between connected services (microservices) within the application.

38. Dynamic Routing Middleware:

• Customizes dynamic routing within the application based on certain conditions, such as navigating between multiple frontends in the same project.

39. SignalR Middleware:

• Supports continuous connection to applications that rely on SignalR for real-time updates.