July 2014
Intermediate to advanced
329 pages
8h 50m
English
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Chapter 9. Cookies and Sessions
HTTP is a stateless protocol. That means that when you load a page in your browser, and then you navigate to another page on the same website, neither the server nor the browser has any intrinsic way of knowing that it’s the same browser visiting the same site. Another way of saying this is that the way the Web works is that every HTTP request contains all the information necessary for the server to satisfy the request.
This is a problem, though: if the story ended there, we could never “log in” to anything. Streaming media wouldn’t work. Websites wouldn’t be able to remember your preferences from one page to the next. So there needs be a way to build state on top of HTTP, and that’s where cookies and sessions enter the picture.
Cookies, unfortunately, have gotten a bad name thanks to the nefarious things that people have done with them. This is unfortunate because cookies are really quite essential to the functioning of the “modern web” (although HTML5 has introduced some new features, like local storage, that could be used for the same purpose).
The idea of a cookie is simple: the server sends a bit of information, and the browser stores it for some configurable period of time. It’s really up to the server what the particular bit of information is: often it’s just a unique ID number that identifies a specific browser so that the illusion of state can be maintained.
There are some important things you need to know about cookies:
- Cookies are not secret ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.