We have several controls in place that trigger the clearing of the caching mechanisms for specific URLs when the content contained within is modified. However, these tools are still under development and do not always catch all the URLs involved in a given update. To clear a particular URL, click on the “Configuration” tab and then the “External Cache Control” link underneath “System” (highlighted in purple below).
This will bring you to the first tab of our external cache control configuration, which allows you to queue a URL. Note that, for performance reasons, we do not default to clearing the page immediately. Instead, the queue is processed every three hours. Adding a URL to the queue will have it wiped the next time your site checks the list (which should be less than three hours). This queue affects both the Varnish cache and the Drupal cache in the correct order, so you do not need to worry about the Drupal cache as well.
Adding a URL to the queue is as simple as entering the URL in the box and clicking “Queue”. You can enter either an absolute URL (like http://www.uottawa.ca/uoweb/en/) or a Drupal URL (like <front> or node/10). We recommend you use the Drupal URL as much as possible, and the un-aliased version of it especially. Drupal will automatically determine the URLs related to it and queue them as well but this is less likely to work if you use an alias or an absolute URL. Note that, once the URL is cleared, the next request to it may take a couple of seconds to load completely.