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BlackBerry Push Development

Control the cache expiry date of pushed content

by BlackBerry Development Advisor ‎02-17-2010 01:42 PM - edited ‎02-18-2010 05:05 PM (3,880 Views)

Summary


This article applies to the following:

  • BlackBerry® devices based on Java®
  • BlackBerry Mobile Data Service


Description


When performing a Browser Channel or Browser Content push, the default amount of time that push content is stored in cache memory varies with the software version used.


In BlackBerry Device Software 3.8 and later, pushed content is removed from the cache after 12 hours.


In BlackBerry Device Software earlier than 3.8, pushed content expires and is removed from the cache after 29 days.


In BlackBerry Device Software 4.2 and later, the default expiry time of URLs without specific expiry times is designed to conform with section 13.6 in RFC document 2616, titled Hypertext Transfer Protocol -- HTTP/1.1.


Note: RFC 2616 is located at http://www.ietf.org/rfc/rfc2616.txt.


If the URL has a query, the default expiry time is zero. If the URL does not have a query, the default expiry time is 12 hours. If the Expires header is specified, the expiry heuristic is not used.


To increase or decrease the time content stored in cache memory, specify a date and time in the HTTP header of the push request with the Expires header. The following example will store content in cache until September 7th, 2005 at 8 AM.



Expires: Wed, 07 Sept 2005 08:00:00 GMT



Note: If the BlackBerry device is running low on flash memory, the browser cache may be cleared to free up needed space. This can result in content being removed from the cache prior to the value specified in the Expires Header.


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