# Final Project: Building a Multithreaded Web Server

It’s been a long journey, but we’ve reached the end of the book. In this chapter, we’ll build one more project together to demonstrate some of the concepts we covered in the final chapters, as well as recap some earlier lessons.

For our final project, we’ll make a web server that says “Hello!” and looks like Figure 21-1 in a web browser.

Here is our plan for building the web server:

1. Learn a bit about TCP and HTTP.
2. Listen for TCP connections on a socket.
3. Parse a small number of HTTP requests.
4. Create a proper HTTP response.
5. Improve the throughput of our server with a thread pool.

Figure 21-1: Our final shared project

Before we get started, we should mention two details. First, the method we’ll use won’t be the best way to build a web server with Rust. Community members have published a number of production-ready crates available at crates.io that provide more complete web server and thread pool implementations than we’ll build. However, our intention in this chapter is to help you learn, not to take the easy route. Because Rust is a systems programming language, we can choose the level of abstraction we want to work with and can go to a lower level than is possible or practical in other languages.

Second, we will not be using async and await here. Building a thread pool is a big enough challenge on its own, without adding in building an async runtime! However, we will note how async and await might be applicable to some of the same problems we will see in this chapter. Ultimately, as we noted back in Chapter 17, many async runtimes use thread pools for managing their work.

We’ll therefore write the basic HTTP server and thread pool manually so that you can learn the general ideas and techniques behind the crates you might use in the future.