cache-control:no-cache; cache-control:max-age:0; cache-control:no-store;
are they different from browser to browser. What should then be considered a standard?
What is the Cache-Control Header. Cache-control is an HTTP header used to specify browser caching policies in both client requests and server responses. Policies include how a resource is cached, where it's cached and its maximum age before expiring (i.e., time to live).
Cache-control is an important way by which developers can dictate how resources will be cached when a user browses the internet. Without cache-control, the browser caching and the resulting experience for the user will be sub-optimal.
To use Cache-Control headers, choose Content Management | Cache Control Directives in the administration server. Then, using the Resource Picker, choose the directory where you want to set the headers. After setting the headers, click 'OK'.
Without the cache control header the browser requests the resource every time it loads a new(?) page.
no-cache
If the no-cache directive does not specify a field-name, then a cache MUST NOT use the response to satisfy a subsequent request without successful revalidation with the origin server. This allows an origin server to prevent caching even by caches that have been configured to return stale responses to client requests.
If the no-cache directive does specify one or more field-names, then a cache MAY use the response to satisfy a subsequent request, subject to any other restrictions on caching. However, the specified field-name(s) MUST NOT be sent in the response to a subsequent request without successful revalidation with the origin server. This allows an origin server to prevent the re-use of certain header fields in a response, while still allowing caching of the rest of the response.
max-age
Indicates that the client is willing to accept a response whose age is no greater than the specified time in seconds. Unless max- stale directive is also included, the client is not willing to accept a stale response.
no-store
The purpose of the no-store directive is to prevent the inadvertent release or retention of sensitive information (for example, on backup tapes). The no-store directive applies to the entire message, and MAY be sent either in a response or in a request. If sent in a request, a cache MUST NOT store any part of either this request or any response to it. If sent in a response, a cache MUST NOT store any part of either this response or the request that elicited it. This directive applies to both non- shared and shared caches. "MUST NOT store" in this context means that the cache MUST NOT intentionally store the information in non-volatile storage, and MUST make a best-effort attempt to remove the information from volatile storage as promptly as possible after forwarding it.
Even when this directive is associated with a response, users might explicitly store such a response outside of the caching system (e.g., with a "Save As" dialog). History buffers MAY store such responses as part of their normal operation.
The purpose of this directive is to meet the stated requirements of certain users and service authors who are concerned about accidental releases of information via unanticipated accesses to cache data structures. While the use of this directive might improve privacy in some cases, we caution that it is NOT in any way a reliable or sufficient mechanism for ensuring privacy. In particular, malicious or compromised caches might not recognize or obey this directive, and communications networks might be vulnerable to eavesdropping.
more information @ http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9.2
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