Cache-Control headers

To specify the operation of the cache, any request can assign a Cache-Control header.

For example, to request the latest copy from the PI System, you can add the following HTTP header to the request:

Cache-Control: no-cache

Alternatively, you can request a maximum age of the data served by the cache with a max-age directive in your Cache-Control header:

Cache-Control: max-age=0 (equivalent to no-cache)

Cache-Control: max-age=120 (the response must be no more than 120 seconds old)

If the cache instance has not been refreshed within the time period specified in the Cache-Control header, the cache instance will be refreshed before the request is served.

Note: Due to performance considerations, you cannot use the Cache-Control header on bulk data operations by default. However, you can change this setting by adding/setting a Runtime configuration IgnoreCacheControlForBulkRequests item and setting Value Type to Boolean and Value to true. See Configuration at runtime.