cache

Cache Control. Allows selectively disabling client-side caching (browser, proxy servers, network caching systems) and caching in the internal Platform Server cache.

cache=cacheControl

cache=clientControl, serverControl

cacheControl

on|off|validate|update

clientControl

on|off

serverControl

on|off

If only one cacheControl value is specified, it is applied to both client and server caches.

The validate keyword allows updating cache entries after image files have changed, without having to wait for the cache entry to expire automatically. Client caching is not affected by this command.

The update keyword can be used to force updating server-side cache entries. This is useful after resources have been changed which are not tracked directly by the cache validation mechanism, such as when a font file is modified without changing its file name or the associated font id.

If specified in a nested request, cache=on enables persistent, server-side caching of the image generated by the nested request. Care should be taken to enable caching for nested requests only when the same nested request is expected to be called repeatedly with exactly the same parameters.

Properties

Request attribute. Applies regardless of current layer setting. Ignored when the request does not return a reply image. clientControl is ignored when client-side caching is disabled by the image catalog (if catalog::Expiration has a negative value).

Client-side cache control (on and off only) is also available for static content requests at /is/content/.

Default

cache=on,on for HTTP requests, cache=off for nested/embedded requests, cache=on for static content requests.