Browsers are divided into negotiated caching and mandatory caching
Mandatory cache
Enforce caching headers. Use Expires in HTTP1.0. Use cache-control in HTTP1.1
Process: Initiates a request —- The browser determines whether the resource matches the “forcible Cache” based on Expires and cache-control —- if the resource matches, it will Cache the resource directly and does not request the server
Cache-control can be:
- Public: All content is cached, as are clients and proxy servers
- Private: All content is cached only by the client (this is the default for cache-control)
- No-cache: indicates the content cached by the client, but whether to cache requires negotiation cache authentication
- No-store: All content is not cached, neither mandatory nor negotiated
- Max-age = XXX: the cache contents will be invalid in XXX seconds
- Must-revalidate: Forces the browser to adhere to the cache rules you set
- Proxy-revalidate: forces the proxy to adhere to the cache rules you set
Negotiate the cache
Force cache invalidity —- Trigger negotiation cache —- The client sends a request to the server with the negotiation cache id —- The server determines whether the cache id is valid
Two things happen
- Negotiation cache takes effect, return 304
- Negotiation cache invalid, returns 200 and result
