Cookies and sessions

Cookie

Cookie yes po; Generated by the server , Send it to the browser , The browser will Cookie Of key/value Save to a text file in a directory , Automatically send this... The next time you request the same website Cookie To server
Cookie Can be used in some WEB Persistent state between site sessions

Session

Session It's another mechanism for recording customer status , be based on Cookie Realization , When the client browser accesses the server , The server records client information in some form on the server , This is it. Session, The client browser only needs to access from Session To find the status of the customer

Differences and connections

contact

Cookie and Session Both are mechanisms for recording customer status

difference

1: Different storage locations

cookie The data information is stored on the client browser .
session The data information of is stored on the server .

2: Different storage capacity

Single cookie Saved data <=4KB, A site can save at most 20 individual Cookie.
about session There is no upper limit , But for the sake of server-side performance ,session Don't store too many things in the , And set up session Delete mechanism .

3: Different storage methods

cookie You can only keep ASCII character string , And it needs to be stored as Unicode Character or binary data .
session Can store any type of data , Including but not limited to string,integer,list,map etc. .

4: Different privacy policies

cookie Visible to clients , People with ulterior motives can analyze the data stored locally cookie And carry on cookie cheating , So it's not safe .
session Store on the server , It's transparent to the client , There is no risk of sensitive information leaking .

5: Cross domain support is different

cookie Support cross domain access .
session Cross domain access is not supported .

Cookie Working schematic diagram

Session Working schematic diagram

JWT token Working schematic diagram