This module is designed to control client side cache functions. Please read Client cache section for more explanation.

With Helicon Jet you can create a set of rules to control content expiration for specific directories, files or content types. Helicon Jet will then put appropriate Cache-Control, Expires and other required HTTP headers into server response to inform a client browser about content expiration and allow client-side caching. The rules could be of two possible types: directory patterns and content-type patterns.

Directory pattern:

Here you can specify an expiration rule for directory or exact file name. As for all other patterns in Helicon Jet you can use wildcards or regular expressions. Regular expression should be preceded with ‘@’ as follows @regex. Use ‘/’ directory pattern to target entire web site. Rules are processed from top to bottom, so more common rules should be placed at the bottom of the list.


Use is the same as for the directory patterns but this pattern will be matched against Content-Type server header. Example values:



Date field specifies when matched content should be considered as expired. Possible format values:

7 days after access

Specifies a time of content expiration relatively, starting from the specified point. The date is set with a human-friendly phrase. Supported keywords: year(s), month(s), week(s), day(s), minute(s) and second(s) separated by a space, comma or ‘and’ word, followed by a keyword after and one of two point keywords – access or modification.

Here are a few examples:

4 days, 3 hours and 20 minutes after access
30 seconds after access
1 month 1 day after modification

Thu, 01 Jan 2009 12:00:01 GMT

Exact expiration date in GMT format as usually used in HTTP headers. For more information please read

Possible values for cache type directives are public, private and nocache.

public – the content cache considered as public. Proxy servers and other intermediate level applications may store this content in their cache to return it for a different customer requests.

private – indicates that content is intended for this user eyes only and thus should be stored only in a user’s local cache.

nocache – disables caching for this content and marks it as already expired. The expiration date for nocache rules is ignored.

For the web applications pages it is recommended to specify a private content type while for page graphics and other linked files you can safely set public cache type.