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Networks, Protocols, and Packets

The development of web applications has never been as popular as it is currently. Web systems, applications, and IoT devices are gaining more space in people's daily lives.

Therefore, the training of developers to master these technologies, languages, frameworks, and tools becomes essential – developers who are not only capable of delivering solutions to end users, but who also have in-depth knowledge of how this entire communication infrastructure works and enables this development.

For this reason, it is necessary to explore the entire infrastructure, communication models, architecture, and purpose of the services that are used to make this web environment increasingly available to end users.

Understanding how a web server works, the difference between a web server and an application server, the protocols involved, the handling of requests and responses, and the frameworks and their functioning is of paramount importance for your career. Current applications are developed as a set of pieces to be fitted together. For example, when you create a web application, lots of frameworks and libraries do the demanding work for you (database connection, some queries, request handling, response generation, etc.). But what about when things don't work? Is the error in your logic, in the misuse of the framework, or in the poor understanding of a communication protocol?

Finally, if you want to be an above-average developer, you will need to understand how technologies work behind the scenes. And that is exactly the purpose of this book: to show, step by step, how we can implement a "simple" web server, an application server, and a web framework, guaranteeing productivity, reliability, and speed in the development of your projects and applications.

Welcome to this journey, which will explore, demystify, and clarify the entire web infrastructure so you can become a developer well above the average.

In this chapter, we will cover the following main topics:

• TCP/IP stack
• The need for a protocol definition
• Implementing a simple protocol using sockets

By the end of the chapter, you will understand how two applications running on different computers connected by a physical channel (a wired or wireless network) can exchange data. It's more complex than writing "Hello" to another user on a chat application. It requires several layers that control and handle different aspects to make this communication viable.