Client Libraries
From VZ Developer Wiki
There are dedicated OpenSocial Client Libraries available in several different languages. See http://wiki.opensocial.org/index.php?title=Client_Libraries for a complete list.
These client libraries have to be configured to work with the VZ endpoints. For information on the endpoints which you have to use, have a look at our REST or RPC API documentation.
For PHP we are providing a ready configured client library at http://github.com/vznet/vz_os_clientlibrary_php
It is based on the official PHP OpenSocial Client Library but has all the extensions and configurations needed to work with VZ properly, so you should definitely use this.