What are web servers and how do they work (with examples httpd and nodejs)

Summary

The video explains what a web server is and how it works, differentiating between static and dynamic content. It discusses blocking single-threaded vs multi-threaded web servers, TCP sockets, and HTTP request-response flows. Concrete examples are provided of setting up a basic Apache server to host static HTML pages and creating a simple web server from scratch using Node.js and Express to handle requests and serve content.

Takeaways

• 😀 A web server is software that serves web content through the HTTP protocol
• 🌟 Static content like HTML/CSS/JS files is easy to host, while dynamic content requires backend processing
• 🚀 Popular web servers like Apache and Nginx handle caching, threading, etc. behind the scenes
• 👨‍💻 You can build a basic web server from scratch using Node.js and Express
• 📝 HTTP status codes indicate responses - 200 OK, 404 Not Found, etc
• 🔀 Web servers reserve memory and threads/processes for each client connection
• 🌐 Browsers handle multiple requests over one TCP connection using keep-alive
• 🛠 Configuring maximum connections/threads is important to prevent server overload
• ✏️ Custom web servers allow full control over statuses, caching, etc.
• 🍀 Load balancing can help scale multiple instances of simple web servers

Q & A

What is a web server?

A web server is a software that serves web content through the HTTP protocol. It is the foundation of the internet and any website must be hosted on a web server.

What is the difference between static and dynamic web content?

Static content includes HTML pages, images, PDFs, etc. that don't change. Dynamic content is generated on-the-fly based on factors like the user, location, etc. using server-side code.

How does a web server work?

A client sends an HTTP request. The web server processes it, retrieves the required resource, and sends an HTTP response with headers and status codes. The client renders the response.

What is a blocking single-threaded web server?

It has one thread to handle requests. If it is busy with one request, other incoming requests have to wait until it is free even if their TCP connections are already established.

What ready-made web servers are mentioned in the video?

Apache HTTP Server, Apache Tomcat, lighttpd, IIS, etc. These provide most required web server functionality out-of-the-box.

How can you write your own web server?

Using Node.js with Express.js or Python with Tornado. These provide handlers for HTTP requests/responses but have to implement other functionality ourselves.

How is Apache HTTP server installed on Debian?

Using the command: sudo apt-get install apache2. Web content goes in /var/www/html folder which Apache automatically serves.

What are the key things that need to be implemented when writing a web server in Node.js?

Import Express, listen on a port, handle HTTP verbs like GET and POST, send back responses and status codes

What status code is used for 'I am a teapot'?

418 - It's an April Fools' joke status code that can be returned if you want to be humorous in your API responses.

How does web server caching using ETags work?

First request - server returns resource + ETag. Subsequent requests - client sends ETag. Server compares. Sends 304 status if match. Else full resource.