Worker can handle more requests with less resources than Prefork. It turns Apache into a multi-process and multi-threaded web server. Not threaded this means in a process list, each Apache process is running a child that is either servicing a request or waiting for a request. Instead of implementing one architecture, Apache provides a variety of MultiProcessing Modules (MPMs): If this happens, you will increase your cache size and not be able to properly cache pages containing query strings.Īpache is an open-source HTTP server for modern operation systems, and the world's most widely used HTTP server today. It's really important to parse and order them or else for each different order (if you used exactly the same parameters), the gateway could create a different cache variation. Check our online documentation to configure eZ and Varnish ( )Ī small tip: be careful with Varnish and query strings. If so, the backend responds with a 304 status code meaning "Not Modified."ĮZ Publish uses both models in order to have less network requests on your architecture. Validation: Gateway could send an HTTP request to the backend (with some headers like Last-Modified and Etag) to determine if the cache is up-to-date or not.Most commonly used headers are Expires and Cache-Control. Expiration: HTTP caches assign expiration times, employing algorithms that use other header values to estimate a plausible expiration time.HTTP Protocol uses two different models to purge cache: This is done by settings HTTP cache headers on the response. To take advantage of the available cache layers, your application must be able to communicate which responses are cacheable and the rules that govern when and how that cache should become stale. If you answer yes to these questions, you should use Varnish.ĮZ Publish 5.x, which is based on the Symfony full-stack framework, implements HTTP Cache - a feature also implemented by Varnish. Do you want to implement a caching strategy without touching (or just barely touching) your codebase?.Does dynamic content in your application change (very) often?. So when and why use Varnish on a web project? The major questions you should ask yourself are: Varnish also supports additional features that can provide much more value such as Edge Side Includes (ESI), HTTP Streaming, Experimental support for Persistent Storage, DNS and Load Balancing. In the real world, however, the server may have to do a bit of work before returning a response to the client. In a perfect world, the server would return a response immediately, without having to do any real work. It's used to reduce load on a web server. Varnish is an HTTP accelerator that delivers cached pages. Now, let's dig into the individual components. That said, eZ's content platform is flexible and organizations can configure the architecture to meet their needs. Moreover, we recommend each layer has at least two servers to avoid a SPOF (Single Point Of Failure). Varnish servers have a mechanism to load balance the requests to eZ's servers.įor organizations using eZ Publish 5.x or eZ Platform, eZ recommends using Memcached to cache and share data (could be PHP sessions, too) and a NAS (Network Attached Storage within a cluster of eZ servers, as shown in the diagram above. Load Balancer dispatches your visitors to your Varnish Servers (cache system). In the typical eZ system architecture, three layers are implemented: Load Balancer, Varnish servers and eZ servers.
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