I have been getting questions about the highscore control of games that are submitted to be hosted on Mashooo and how to manage to show it inside the application from a different server.

I thought I might as well show it as a post for others to benefit from this useful piece of information. I'm just pasting what I explained to the last game developer who asked:

Since your high score system is hosted on your server and the Silverlight application would be hosted on our server the Silverlight application needs to make what is referred to as "cross domain calls".

For a Silverlight application to be able to access files on a different server than the one it is hosted on (cross domain calls) you have to add a special file in the root directory of your server.

Here's the explanation of what you need to do:

"To enable a Silverlight control to access a service in another domain, the service must explicitly opt-in to allow cross-domain access. By opting-in, a service states that the operations it exposes can safely be invoked by a Silverlight control, without potentially damaging consequences to the data the service stores.

Silverlight 2 supports two different mechanisms for services to opt-in to cross-domain access:

 -Place a clientaccesspolicy.xml file at the root of the domain where the service is hosted to configure the service to allow cross-domain-access.

 -Place a valid crossdomain.xml file at the root of the domain where the service is hosted. The file must mark the entire domain public. Silverlight supports a subset of the crossdomain.xml schema."

For more information visit the following links:

http://msdn.microsoft.com/en-us/library/cc197955(VS.95).aspx

http://msdn.microsoft.com/en-us/library/cc645032(VS.95).aspx

As we speak, at Mashooo.com we are working on a highscore keeping system that allows game developers to use it instead of having to create one themselves. I'll keep you posted on this.

Update 2009 Oct 6: Mashooo highscores and achievements service is ready!