They consist of:
- HTTP response header of the message
- HTTP request header of the message
- File of cookies in the user's machine (managed by the browser)
- Back-End Database
Cookies are collected within the authorization credentials and user information.
Are intended to speed up responses to user requests. If the user sets the browser to access the web via a proxy, the browser sends requests to the proxy. If the object is cached on the proxy it is immediately sent. The operation of the proxy is the servant (client-server). In this way the external traffic is reduced,decreasing the response time and allow the operation to ISPs notwell-connected.
The cache enhances performance but also create problems of consistency of the data contained within them.
Some settings in requests and responses:
-NO-CACHE, which prohibits the info will be cached (request +response)
-NO-STORE, prevents the details are put on a medium-volatile(request + response)
-NO-TRANSFORM, prevents the representation (request +response)
-MAX-AGE, indicates how long the most of the info can becached (request + response)
MUST-REVALIDATE / PROXY, requires all or only to renew itsproxy cache (answers)
-ONLY-IF-CACHED, response only if cached (required)