HttpCacheBundle

The SuluHttpCache bundle provides tight integration between Sulu and HTTP caching proxies.

Handlers

All of the functionality of the Sulu HTTP cache implementation is encapsulated in “handlers”. Handlers are responsible primarily for handling the caching of Sulu Structure objects (e.g. Page and Snippet classes).

Most handlers will need to talk to a HTTP proxy cache implementation. The cache implementations are provided by the FOSHttpCache component. Examples of handlers which do not need to talk to a cache implementation are the DebugHandler and the PublicHandler.

Handler classes implement the HandlerInterface and are further specialized with three further interfaces:

  • HandlerFlushInterface: This handler is capable of being “flushed” - this will normally be a proxy for ProxyClient#flush.
  • HandlerInvalidateInterface: This handler can invalidate the cache.
  • HandlerUpdateResponseInterface: This handler can update the response.

Aggregate Handler

Implements: flush, invalidate and update response.

The aggregate handler is special as it aggregates other handlers so that you can apply multiple handlers at the same time.

This is the default handler and by default it will aggregate all enabled handlers.

Debug Handler

Implements: update response.

The debug handler simply adds debug information to your response:

  • x-sulu-handler: The handlers which are enabled
  • x-sulu-proxy-client: The name of the proxy client being used
  • x-sulu-structure-type: The structure type for which the response is being returned
  • x-sulu-structure-uuid: The UUID of the Structure
  • x-sulu-page-ttl: Send the TTL (time to live) to the proxy client with the header X-Resverse-Proxy-TTL (which is defined as a constant in the Sulu\Component\HttpCache class).

For example:

x-sulu-handlers: paths, public, debug
x-sulu-proxy-client: symfony
x-sulu-structure-type: OverviewPageCache
x-sulu-structure-uuid: 22a92d46-74ab-46cc-b47c-486b4b8a06a7
x-sulu-page-ttl: 2400

Paths Handler

Implements: flush, invalidate and update response.

The paths handler will invalidate all the URLs associated with the subject Structure when it is updated. For example, if a page is located at http://sulu.lo/de/my/page and http://sulu.lo/en/my/page then these two URLs will be purged in the cache, and their contents will be updated when they are next requested.

Note

When using the paths handler you need to be aware that pages which reference the structure being invalidated will not be updated - for example pages which aggregate the subject structure in a SmartContent content type.

Public Handler

Implements: update response.

The public handler adds generic caching information to the response which will be consumed by the users web browser. For example a max-age time of 3600 will instruct the users browser to locally cache the page for one hour before requesting it from the server again.

The following are example headers added by the public handler (the X-Reverse-Proxy header will normally be removed by the cache implementation):

Cache-Control: max-age=240, public, s-maxage=240
X-Reverse-Proxy-TTL: 2400

Tags Handler

The tags handler is the most comprehensive cache invalidation strategy, it will invalidate both the URLs of the structure and the URLs of the pages which display references to the structure. . It must be used in conjunction with a proxy client which supports Banning. Currently this handler can only be used with Varnish.

This handler works by sending all of the UUIDs of the structures which are contained in a page response to the proxy client. The proxy client can then store this information along with the cached HTML response.

When you update any structure in the admin interface it will instruct the HTTP proxy to purge all the caches which have a reference to the UUID of the structure you have updated.

Example header sent by the tags handler (which will be removed by varnish):

X-Cache-Tags: 22a92d46-74ab-46cc-b47c-486b4b8a06a7,cf4a07fe-91d0-41be-aed8-b1c9ee1eb72a

This header will be written at the end of the response by using the Reference Store. This service collects the entities/documents which was used to render the page.

Proxy Clients

Symfony Http Cache

The Symfony HTTP cache is the default caching client for Sulu CMF. It is integrated directly into Sulu.

It works by “wrapping” the kernel. You can find it in the website front controller web/website.php:

// web/website.php
// ...

// Comment this line if you want to use the "varnish" http
// caching strategy. See http://sulu.readthedocs.org/en/latest/cookbook/caching-with-varnish.html
 if (SYMFONY_ENV != 'dev') {
    require_once __DIR__ . '/../app/WebsiteCache.php';
    $kernel = new WebsiteCache($kernel);
}

It will need to be disabled when using varnish.

Varnish

The varnish proxy client is provided by the FOSHttpCache component.

See Caching with Varnish for more information about setting up varnish.

Default configuration

# Default configuration for extension with alias: "sulu_http_cache"
sulu_http_cache:

    default_handler:      aggregate

    # Configuration for structure cache handlers
    handlers:
        aggregate:
            enabled:              true

            # Handlers to aggregate, e.g. all or any of tags, path, public
            handlers:             []
        public:
            enabled:              false
            max_age:              300
            shared_max_age:       300

            # Use the dynamic pages cache lifetime for reverse proxy server
            use_page_ttl:         true
        paths:
            enabled:              false
        tags:
            enabled:              false
        debug:
            enabled:              false
    proxy_client:
        symfony:
            enabled:              false
        varnish:
            enabled:              false

            # Addresses of the hosts Varnish is running on. May be hostname or ip, and with :port if not the default port 80.
            servers:              # Required

                # Prototype
                name:                 ~

            # Default host name and optional path for path based invalidation.
            base_url:             null