As of Tridion 2013, it is possible to get and set claims via OData. This serves two purposes:

1. You can now configure Session Preview on websites that are not .NET or Java based, e.g. Ruby, PHP or JSF based.

2. On the product roadmap the CD layer of the Tridion stack is moving towards a web-service model so that the CD API is a basic proxy client, instead of a mountain of jars and config files.

This means that cartridges run on the cd_webservice as well as the website, and XPM is plugged in via it's Session Preview cartridge. So the configuration of both, website and web service, is most likely because of class dependencies inside the cartridge.

As of Tridion 2013, it is possible to get and set claims via OData. This serves two purposes:

1. You can now configure Session Preview on websites that are not .NET or Java based, e.g. Ruby, PHP or JSF based.

2. On the product roadmap the CD layer of the Tridion stack is moving towards a web-service model so that the CD API is a basic proxy client, instead of a mountain of jars and config files.

This means that cartridges run on the cd_webservice as well as the website, and XPM is plugged in via its Session Preview cartridge. So the configuration of both, website and web service, is most likely because of class dependencies inside the cartridge.