A History of State
Get a brief introduction to model application rules as states and transitions.
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Before we move on to where we’re going, though, let’s see where we’ve been.
States and transitions
Early client-server applications were stateful. Clients connected to the server and stayed connected while they passed messages back and forth. We can think of mainframe applications with dedicated terminals as clients.
That worked well, but it meant that the number of possible clients was limited by system resources like memory, CPU, and the number of concurrent processes the system could support.
The web gets around these limitations because of HTTP’s nature. When a client makes an HTTP request to a server, it must supply all the data the server will need to fulfill that request. Once the server sends its response, it forgets everything it knows about both the request and the client.
This ...