About CDNs

Division of responsibilities:


CDN: store static resources such as HTML, CSS, JS, etc.;
reverse proxy: separate static and dynamic, and only cache static resources requested by users;
distributed cache: cache hot data in the database;
local cache: cache common data such as application dictionaries ;
 


Request process:


(1) The browser initiates a request to the client, and returns directly if the CDN has a cache;


(2) If the CDN has no cache, it accesses the reverse proxy server;


(3) If the reverse proxy server has a cache , it directly returns Return;


(4) If the reverse proxy server has no cache or dynamic request, access the application server;


(5) The application server accesses the local cache; if there is a cache, return to the proxy server and cache the data; (dynamic requests are not cached)


( 6) If there is no data in the local cache, read the distributed cache; and return to the application server; the application server caches the data to the local cache (part);


(7) If there is no data in the distributed cache, the application reads the database data, And put into distributed cache;