6.1 Configuring Caching Options

The Cache Options allow you to control how the Access Gateway caches objects.

  1. Click Access Gateways > Edit > Cache Options.

    Global Cache Options
  2. To disable caching of all Web server content, select Disable Caching.

    When this option is selected, all other caching options are disabled.

  3. (Access Gateway Appliance) Configure the Cache Management options:

    Enable Caching of Objects with a Question Mark: If this option is selected, a cacheable object is cached if it has a question mark in the URL.

    Enable Caching of Objects with CGI in the Path: If this option is selected, a cacheable object is cached if it has /cgi in its URL.

    Objects that meet these criteria are only cached if they are also cacheable objects. Web server administrators can mark objects as non-cacheable. When so marked, these objects are not cached, even when the above options are selected.

    If you disable both of these options, it does not mean that objects with question marks or cgi in their paths cannot be cached. These objects can match some other criteria and be cached.

  4. (Access Gateway Appliance) Configure the Cache Tuning options.

    These options restrict or enable functionality that affects all the resources protected by the Access Gateway.

    Refresh Requests from Browser: When a user clicks Refresh or Reload in the browser, this action sends a new request to the Web server. Select one of the following options to control how the Access Gateway handles the request:

    • Refill: Causes the proxy service to send the request to the Web server.

    • Ignore: Causes the proxy service to ignore the request and send the data from cache without checking to see if the cached data is valid.

  5. Modify the Cache Freshness settings. Use the Reset button to return these settings to their default values.

    These options govern when the proxy service revalidates requested cached objects against those on their respective origin Web servers. If the objects have changed, the proxy service re-caches them.

    WARNING:Enter whole number values. Decimal values (2.5) are not supported and generate an XML validation error.

    HTTP Maximum: Specifies the maximum time the proxy service serves HTTP data from cache before revalidating it against content on the origin Web server. No object is served from cache after this value expires without being revalidated.

    This overrides a freshness or Time to Expire directive specified by the Webmasters if they specified a longer time.

    You use this value to reduce the maximum time the proxy service waits before checking whether requested objects need to be refreshed. The default is 6 hours.

    HTTP Default: Specifies the maximum time the proxy service serves HTTP data for which Webmasters have not specified a freshness or Time to Expire directive. The default is 2 hours.

    HTTP Minimum: (Access Gateway Appliance) Specifies the minimum time the proxy service serves HTTP data from cache before revalidating it against content on the origin Web server. No requested object is revalidated sooner than specified by this value.

    This overrides the freshness or Time to Expire directive specified by the Webmasters if they specified a shorter time.

    You can use this value to increase the minimum time the proxy service waits before checking whether requested objects need to be refreshed. This parameter does not override No Cache or Must Revalidate directives from the origin Web server.

    The default value is 0, which allows the proxy service to honor the Time To Expire directive of each object (unless it is longer than the HTTP Maximum option). If the HTTP Minimum option is set to a value other than 0, the value overrides any object’s Time to Expire directive that is shorter than the value set. The default is 0.

    Continue Fill Time: (Access Gateway Appliance) Specifies the how long the proxy service ignores browser request cancellations and continues downloading objects from the target Web server until the download is complete. The default is 1 second.

    HTTP Retries: (Access Gateway Appliance) Specifies the number of retry requests to issue to a Web server. The default is 4 retries.

  6. To save your changes to browser cache, click OK.

  7. To apply the changes, click the Access Gateways link, then click Update > OK.