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Version Feed
Development
Feed actions
Creating functions called changes or allchanges on any of your page types or controllers will cause confusion with
the extensions defined on the extension.
Default RSS action
Templates can offer a "Subscribe" link with a link to the most relevant RSS feed. This will default to the changes feed
for the current page. You can override this behaviour by defining the getDefaultRSSLink function in your page type
and returning the URL of your desired RSS feed:
:::php
class MyPage extends Page {
function getDefaultRSSLink() {
return $this->Link('myrssfeed');
}
}
This can be used in templates as $DefaultRSSLink.
Rate limiting and caching
If the Policy Filter Module has been installed then additional rate limiting and caching functionality will be applied automatically. For more information on how this modules works see the policy filter documentation.
By default all content is filtered based on the rules specified in versionfeed/_config/versionfeed.yml.
For large servers with a high level of traffic (more than 1 visits every 10 seconds) the default settings should be sufficient.
For smaller servers where it's reasonable to apply a more strict approach to rate limiting, consider setting the
ContentController.filter_policy.rate_lock_byitem config to false, meaning that a single limit will be
applied to all URLs. If left on true, then each URL will have its own rate limit, and on smaller servers with lots of
concurrent requests this can still overwhelm capacity. This will also leave smaller servers vulnerable to DDoS
attacks which target many URLs simultaneously. This config will have no effect on the allchanges method.
ContentController.filter_policy.rate_lock_byuserip can also be set to true in order to prevent requests
from different users interfering with one another. However, this can provide an ineffective safeguard
against malicious DDoS attacks which use multiple IP addresses.
Another important variable is the ContentController.filter_policy.rate_lock_timeout config, which is set to 10
seconds by default. This should be increased on sites which may be slow to generate page versions, whether
due to lower server capacity or volume of content (number of page versions). Requests to this page after
the timeout will not trigger any rate limit safeguard, so you should be sure that this is set to an appropriate level.
The default cache of 1 hour can also be adjusted by setting the ContentController.filter_policy.cache_lifetime
to any time period in seconds.