Help for Cached File Expiration

Use this form to define settings related to the expiration of cached files, and to create or modify lists of rules that define when you want various cached files to expire.

File Expirations

You can set values that define how you want your server to handle expired files.

You can also create or modify lists of rules that define when cached files expire. These rules override expiration dates in the files' URL request headers. When the server runs the storage reclamation process (also known as garbage collection), it removes cached files that have expired. You can use three types of lists for determining file expirations:

• Remove all cached files older than a specified expiration time - any cached file that matches a template in this list expires after the corresponding expiration time.
• Remove unused cached files after a specified expiration time - any cached file that has not been used and that matches a template in this list expires after the corresponding expiration time.
• Remove all documents that do not contain expiration time information in their header after a specified expiration time - any cached file that does not have an expiration time in its header and matches a template in this list expires after the corresponding expiration time.

To define file expiration settings:

1. Define the following settings:
• Enable cached file expiration checking - check this box if you do not want the server to be able to send clients cached files that have expired. Generally, you will want to keep this setting checked. An exception might be if you were demonstrating the server and did not particularly care about the content being returned.
• Disable retrieval of files from remote servers - check this box if you do not want the server to retrieve files from remote servers. If you check this setting, your server runs in stand alone cache mode, which means it can only return files it has already stored in its cache. Generally, you will not want to check this setting.

  An example of when you might want to run in stand alone cache mode is if you are using the server for a demonstration and know that all the files you want to use are already stored in the cache. Running the server in this mode can reduce the time it takes to retrieve files. Typically, you would also un-check the file expiration checking setting when running the server in stand alone cache mode.

• Last modified factor - enter a fraction in the form of "0.x". The server uses this fraction to set expirations for files it retrieves that have a Last-Modified date but no Expires date. The server uses the Last-Modified date to determine how long it has been since the file was modified. The server multiplies that length of time by the value on this setting. The server uses the result of this calculation to assign the file an expiration date. For example, if this setting is 0.1, the server would set expiration at 2 days for a file modified 20 days ago.
2. If you want to use the changes you make to the form, select the Apply button. If you want to go back to the values that were on the form before you made changes, select the Reset button.

To insert a new entry:

1. Select either the Insert before or Insert after button for the expiration rules list you are adding to.
2. Select an Index number.

   Your choices in steps 1 and 2 indicate the position you want the new entry to have in the list. For example, if you select Insert before and Index 2, the new entry will be second in the list. If you select Insert after and Index 4, the new entry will be fifth in the list.

3. Create the new entry by filling in the following fields:
• URL Request Template - the template that defines the URLs of files you want to associate with an expiration time. You can use the asterisk (*) wildcard character in the template.
• Expiration Time - the length of time between when a file is cached and when it expires. The time can be specified in any combination of months, weeks, days, and hours. For example:

  1 month 2 days
3 weeks
18 days

4. If you want to use the changes you make to the form, select the Apply button. If you want to go back to the values that were on the form before you made changes, select the Reset button.

To replace an entry:

1. Select the Replace button for the expiration rules list you are modifying.
2. Select the Index number of the entry you want to replace.
3. Create the new entry by filling in the following fields:
• URL Request Template - the template that defines the URLs of files you want to associate with an expiration time. You can use the asterisk (*) wildcard character in the template.
• Expiration Time - the length of time between when a file is cached and when it expires. The time can be specified in any combination of months, weeks, days, and hours. For example:

  1 month 2 days
3 weeks
18 days

4. If you want to use the changes you make to the form, select the Apply button. If you want to go back to the values that were on the form before you made changes, select the Reset button.

To remove an entry:

1. Select the Remove button for the expiration rules list you are modifying.
2. Select the Index number of the entry you want to remove.
3. If you want to use the changes you make to the form, select the Apply button. If you want to go back to the values that were on the form before you made changes, select the Reset button.