Chapter 1.  Chat Application with Web Sockets

Go is great for writing high-performance, concurrent server applications and tools, and the Web is the perfect medium over which to deliver them. It would be difficult these days to find a gadget that is not web-enabled and this allows us to build a single application that targets almost all platforms and devices.

Our first project will be a web-based chat application that allows multiple users to have a real-time conversation right in their web browser. Idiomatic Go applications are often composed of many packages, which are organized by having code in different folders, and this is also true of the Go standard library. We will start by building a simple web server using the net/http package, which will serve the HTML files. We will then go on to add support for web sockets through which our messages will flow.

In languages such as C#, Java, or Node.js, complex threading code and clever use of locks need to be employed in order to keep all clients in sync. As we will see, Go helps us enormously with its built-in channels and concurrency paradigms.

In this chapter, you will learn how to:

• Use the net/http package to serve HTTP requests
• Deliver template-driven content to users' browsers
• Satisfy a Go interface to build our own http.Handler types
• Use Go's goroutines to allow an application to perform multiple tasks concurrently
• Use channels to share information between running goroutines
• Upgrade HTTP requests to use modern features such as web sockets
• Add tracing to the application to better understand its inner working
• Write a complete Go package using test-driven development practices
• Return unexported types through exported interfaces

Note

Complete source code for this project can be found at https://github.com/matryer/goblueprints/tree/master/chapter1/chat. The source code was periodically committed so the history in GitHub actually follows the flow of this chapter too.