For quite some time, client-server architecture was one of the most widespread patterns in large-scale software development. Even systems that run purely on one computer are often designed this way. This allows us to clearly separate concerns: the server takes care of heavy business logic, persistent storage, accessing data from third-party services, and so on, and the client is responsible solely for presentation to end users.
This architecture also allows us to have multiple clients connected to one backend: mobile apps, IoT devices, third-party REST API consumers (for example, external developers), and the web, for example.
In the early days of web development, it was not that way though. Servers were responsible for everything. Usually, it was a combination of DB, app itself, template engine, a bunch of static assets (images, CSS, and so on) all baked together into a monolithic app. Later on, it became obvious that this kind of architecture does not scale well.
Nowadays, the modern web is moving back to client-server architecture with a clean separation of concerns and concrete responsibilities for each component. Server-side apps deal with data and client-side apps deal with presentation of that data.
We will cover the following topics in this chapter:
- What is a single-page app?
- Introduction to React
- Single-page app performance issues
- Server-side rendering with React
