Get JSon of report or analyzer report

Hi,
in which way is possible to call a web service in order to get the result set of a report or analyzer report (available in Pentaho EE) in a JSon format?

I'm not able to find any documentation on the web relating to the web services available within Pentaho platform both CE and EE.

Any help is really appreciated.

I'm using Pentaho 4.8 CE and EE

Regards

Nico