Dedicated image server in Sitecore – part 2

I have earlier blogged about setting up a dedicated image server for Sitecore here. The implementation required some customization of the LinkProvider, but from Sitecore 6.3 it is possible to achieve the same just using configuration.

A dedicated media server can be used to serve media on a separate URL, so that you can optimize performance due to limitations on the amount of connections the browser can open to the domain, which I also described in the last post. Further it can be used to optimize your server for handling media and supporting a CDN.

As mentioned it is now possible to have a separate server for media by configuration. In this scenario you might have a dedicated publishing target for media, and this should just be a standard Sitecore installation, which then only handles media by directing the DNS for your image URL to this server. For instance I have setup three Sitecore installations – one as a content manager server, one as the dedicated image server and one as content delivery server. The domain for my content management server is http://sitecore63/, the one for my image server is http://sitecore63imageserver/ and the content delivery server has the domain http://sitecore63cd/. What I then want to achieve is:

1. That my content management server serves images in the normal way, so that the editors can insert, alter and preview images without having to publish.
2. On my content delivery servers I want my images to be served by the image server.

The first goal is easy. I just leave every configuration to the standard. This means that the content management server serves media itself.
The second goal requires some configuration changes. On the content delivery servers I must make all media references point to the image server. This can be done by setting the Media.MediaLinkPrefix in the web.config to the domain name of the image server plus the media prefix I want. For instance like this:

<setting name=”Media.MediaLinkPrefix” value=”http://sitecore63imageserver/~/media/” />

This means that all media items on the content delivery server(s) will be prefixed with the above url:

<img width=”128″ height=”128″ alt=”” src=”http://sitecore63imageserver/~/media/Images/user.ashx?w=128&amp;h=128&amp;as=1“>

So in this scenario the html is delivered by http://sitecore63cd and the image is served by http://sitecore63imageserver. In the content management environment, the media is served locally. Now this is a lot easier, than the customization you needed in older versions of Sitecore.

If you want another media prefix then the standard /~/media, you also need to make the media server handle these requests as media. This is done by adding the prefix to the <mediaPrefix> element in the web.config and add the prefix to the customHandlers section in the web.config.