Writing a Web Caching Resource Policy
To write a Web Caching resource policy:
- In the admin console, select Users > Resource Policies > Web.
- If your administrator view is not already configured to show caching policies, make the following modifications:
- Click the Customize button in the upper right corner of the page.
- Select the Caching check box.
- Select the Policies check box below the Caching check box.
- Click OK.
- Select the Caching > Policies tab.
- On the Web Caching Policies page, click New Policy.
- Enter a name to label this policy (required) and a description of the policy (optional).
- In the Resources section, specify the resources to which this policy applies.
- In the Roles section, specify:
- Policy applies to ALL roles - To apply this policy to all users.
- Policy applies to SELECTED roles - To apply this policy only to users who are mapped to roles in the Selected roles list. Make sure to add roles to this list from the Available roles list.
- Policy applies to all roles OTHER THAN those selected below - To apply this policy to all users except for those who map to the roles in the Selected roles list. Make sure to add roles to this list from the Available roles list.
- In the Action section, select one of the following options:
- Smart Caching (send headers appropriate for content and browser) - Select this option to send a cache-control:no-store header or a cache-control:no-cache header based on the user's Web browser and content type.
When you select this option, the system makes media files and zip files work properly by removing their origin server's cache-control headers. For example, the following logic searches for "msie" or "windows-media-player" in user-agent headers in order to remove cache or cache-control:no-store response headers and make the files cacheable:
(if content type has "audio/x-pn-realaudio" OR
if content type begins with "video/" OR
if content type begins with "audio/" OR
if content type is "application/octet-stream" and the file extension begins with "rm" or "ram"
)
If the system finds "msie" or "windows-media-player" in the user-agent header and any of the following apply:
- Request is for Flash, .xls, .pps, .ppt files
- Content-type is application/, text/rtf, text/xml, model/
- Origin server sends a content-disposition header
then the system sends the cache-control:no-store header and removes the origin server's cache-control header.
In all other cases, the system adds the pragma:no-cache or cache-control:no-store response headers.
Citrix .ica and QuickPlace files get some special treatment. Citrix .ica files are always cacheable and get cache-control-private as well. QuickPlace files that do not match a specified rule files (which takes precedence) get CCNS and cache-control:private.
Also note that if you select this option, enable GZIP compression, and try to access a text file attachment using Domino Web Access 6.5 through Internet Explorer, you cannot open the attachment. To enable text attachments, you must either install the Internet Explorer 323308 patch or enable the Don't Cache (send "Cache Control: No Store") option.
- Don't Cache (send "Cache Control: No Store") - Select this option to deliver attachments to Internet Explorer without saving them to the disk. (The browser temporarily writes files to the disk, but immediately removes them once it has opened the file in the browser.) When you select this option, the system removes the origin server's cache-control header and adds a cache-control:no-store response header if the user-agent string sent by the browser contains "msie" or "windows-media-player."
This option might slow browsing by causing repeated content fetches, which can cause performance issues on very slow connections. Alternatively, you can specify a policy that allows certain kinds of content to be cached, such as images that do not exceed a specified size limit.
- Don't Cache (send "Pragma: No Cache") - Select this option to prevent the user's browser from caching files to the disk. When you select this option, the system adds the standard HTTP pragma:no-cache header and cache-control:no-cache (CCNC) header (HTTP 1.1) to response files. Also, the system does not forward the origin server's caching headers, such as age, date, etag, last-modified, expires.
When no-cache headers are present on certain types of attachments (PDF, PPT, streaming files), Internet Explorer does not properly render the documents because the rendering process requires the browser to temporarily writes these files to cache.
- Unchanged (do not add/modify caching headers) - Select this option to not add the pragma:no-cache or cache-control:no-store response headers and forwards the origin server's caching headers.
- Remove Cache-Control: No-Cache|No - Store-Select this option to help "cache" files sent by web applications in an HTTPS environment. This option removes the Cache Control:No Cache and Pragma:no-cache headers. Removing these headers is necessary to allow the successful download of certain file types. These headers work fine in an HTTP environment, but fail in an HTTPS environment where the associated pages become uncacheable, preventing the user's web browser from downloading the pages.
Use this option when you want the end user to have the ability to download and open a file that will be opened by another third-party application. For example, zip files and wav files are stored on disk and opened by another application.
- Use Detailed Rules - To specify one or more detailed rules for this policy.
- Click Save Changes.
- On the Web Caching Policies page, order the policies according to how you want to evaluate them. Keep in mind that once the system matches the resource requested by the user to a resource in a policy's (or a detailed rule's) Resource list, it performs the specified action and stops processing policies.