I started using PHP a couple of months ago. For the sake of creating a login system for my website, I read about cookies and sessions and their differences (cookies are stored in the user's browser and sessions on the server). At that time, I preferred cookies (and who does not like cookies?!) and just said: "who cares? I don't have any good deal with storing it in my server", so, I went ahead and used cookies for my bachelor graduation project. However, after doin' the big part of my app, I heard that for the particular case of storing user's ID, sessions are more appropriate. So I started thinking about what would I say if the jury asks me why have you used cookies instead of sessions? I have just that reason (that I do not need to store internally information about the user). Is that enough as a reason? or it's more than that?
Could you please tell me about advantages/disadvantages of using cookies for keeping User's ID?
感谢大家在StackOverflow!
博士TL;
| Criteria / factors |
Sessions |
Cookies |
| Epoch (start of existence) |
Created BEFORE an HTTP response |
Created AFTER an HTTP response |
| Availability during the first HTTP request |
YES |
NO |
| Availability during the succeeding HTTP requests |
YES |
YES |
| Ultimate control for the data and expiration |
Server administrator |
End-user |
| Default expiration |
Expires earlier than cookies |
Lasts longer than sessions |
| Server costs |
Memory |
Memory |
| Network costs |
None |
Unnecessary extra bytes |
| Browser costs |
None |
Memory |
| Security |
Difficult to hijack |
Easy to hijack |
| Deprecation |
None |
Now discouraged in favor of the JavaScript "Web Storage" |
细节
优点和缺点是主观的。它们可能会导致一种两分法(对一些人来说是优势，但对另一些人来说是劣势)。相反，我列出了可以帮助你决定选择哪一个的因素。
第一个HTTP请求-响应期间的存在
假设您是服务器端人员，希望同时处理会话和cookie。第一次HTTP握手是这样的:
浏览器准备HTTP请求——SESSIONS:不可用;COOKIES:不可用
浏览器发送HTTP请求
服务器接收HTTP请求
服务器处理HTTP请求——SESSIONS:已存在;饼干:投
服务器发送HTTP响应
浏览器接收HTTP响应
浏览器处理HTTP响应——SESSIONS:不可用;饼干:存在
在步骤1中，浏览器不知道会话和cookie的内容。
在步骤4中，服务器可以有机会设置会话和cookie的值。
后续HTTP请求-响应期间的可用性
浏览器准备HTTP请求——SESSIONS:不可用;饼干:可用
浏览器发送HTTP请求
服务器接收HTTP请求
服务器处理HTTP请求——SESSIONS:可用;饼干:可用
服务器发送HTTP响应
浏览器接收HTTP响应
浏览器处理HTTP响应——SESSIONS:不可用;饼干:可用
有效载荷
假设在一个网页中，你加载了example.com托管的20个资源，这20个资源将携带关于cookie的额外字节信息。即使它只是一个CSS或JPG图像的资源请求，在通往服务器的途中，它仍然会在它们的头文件中携带cookie。对JPG资源的HTTP请求应该携带一堆不必要的cookie吗?
弃用
会话是不可替代的。对于cookie，在浏览器中存储数据有许多其他选项，而不是老式的cookie。
用户数据的存储
会话对于存储用户数据更安全，因为最终用户不能修改它，只能在服务器端进行设置。另一方面，cookie可能被劫持，因为它们只是存储在浏览器上。
