Middleware is a software layer that processes requests and responses between a client and a server. It acts as a bridge that runs code before or after a request reaches the final application logic, allowing developers to handle tasks like authentication, logging, and request validation.
In backend development, middleware is commonly used to control the flow of HTTP requests in web applications. It can modify requests, block unauthorized access, or add additional processing steps before sending a response.
For example:
- A login middleware checks if a user is authenticated before accessing a protected page.
- A logging middleware records every incoming request for monitoring purposes.
- A security middleware blocks requests from suspicious IP addresses.
- A JSON parsing middleware converts incoming request data into a usable format.
Common technologies and concepts related to middleware include:
- Express.js Middleware
- Request/Response Cycle
- Authentication & Authorization
- API Gateway
- Logging Systems
- Error Handling
- Web Frameworks
- Node.js Backend
- Request Filtering