mirror of
https://github.com/silverstripe/silverstripe-versionfeed
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73 lines
3.9 KiB
Markdown
73 lines
3.9 KiB
Markdown
# Version Feed
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## Development
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### Feed actions
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Creating functions called `changes` or `allchanges` on any of your page types or controllers will cause confusion with
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the extensions defined on the extension.
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### Enabling / Disabling
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By default the `allchanges` and `changes` feed are disabled.
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The `allchanges` feed can be enabled by setting the `SilverStripe\VersionFeed\VersionFeed.allchanges_enabled` config to true. If this is true, then the allchanges feed can still be disabled by unchecking the "All page changes" checkbox in the "Settings" section in the CMS.
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Likewise, the `changes` feed for each page can be globally enabled by setting the `SilverStripe\VersionFeed\VersionFeed.changes_enabled`
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config to true. If this is true, then each page can still be individually disabled by unchecking the
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'Make history public' checkbox in the CMS under page settings.
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See [user documentation on enabling / disabling](userguide/index.md#enabling--disabling).
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### Default RSS action
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Templates can offer a "Subscribe" link with a link to the most relevant RSS feed. This will default to the changes feed
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for the current page. You can override this behaviour by defining the `getDefaultRSSLink` function in your page type
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and returning the URL of your desired RSS feed:
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```php
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class MyPage extends Page
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{
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public function getDefaultRSSLink()
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{
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return $this->Link('myrssfeed');
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}
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}
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```
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This can be used in templates as `$DefaultRSSLink`.
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### Rate limiting and caching
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By default all content is filtered based on the rules specified in `vendor/silverstripe/versionfeed/_config/versionfeed.yml`.
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Two filters are applied on top of one another:
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* `SilverStripe\VersionFeed\Filters\CachedContentFilter` provides caching of versions based on an identifier built up of the record ID and the
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most recently saved version number. There is no configuration required for this class.
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* `SilverStripe\VersionFeed\Filters\RateLimitFilter` provides rate limiting to ensure that requests to uncached data does not overload the
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server. This filter will only be applied if the `SilverStripe\VersionFeed\Filters\CachedContentFilter` does not have any cached record
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for a request.
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Either one of these can be replaced, added to, or removed, by adjusting the `SilverStripe\VersionFeed\VersionFeedController.dependencies`
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config to point to a replacement (or no) filter.
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For smaller servers where it's reasonable to apply a strict approach to rate limiting the default
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settings should be sufficient. The `SilverStripe\VersionFeed\Filters\RateLimitFilter.lock_bypage` config defaults to false, meaning that a
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single limit will be applied to all URLs. If set to true, then each URL will have its own rate limit,
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and on smaller servers with lots of concurrent requests this can still overwhelm capacity. This will
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also leave smaller servers vulnerable to DDoS attacks which target many URLs simultaneously.
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This config will have no effect on the `allchanges` method.
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`SilverStripe\VersionFeed\Filters\RateLimitFilter.lock_byuserip` can be set to true in order to prevent requests from different users
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interfering with one another. However, this can provide an ineffective safeguard against malicious DDoS attacks
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which use multiple IP addresses.
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Another important variable is the `SilverStripe\VersionFeed\Filters\RateLimitFilter.lock_timeout` config, which is set to 5 seconds by default.
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This should be increased on sites which may be slow to generate page versions, whether due to lower
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server capacity or volume of content (number of page versions). Requests to this page after the timeout
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will not trigger any rate limit safeguard, so you should be sure that this is set to an appropriate level.
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You can set the `SilverStripe\VersionFeed\Filters\ContentFilter.cache_lifetime` config in order to control the maximum age of the cache.
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This is an integer value in seconds, and defaults to 300 (five minutes). Set it to 0 or null to make this
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cache unlimited.
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