For users in a Google domain, there's a property called gidNumber. The only way I know of how I can access this id is by connecting to the Google Ldap. When I do a query in Google Admin Directory, I cannot find this property. Are there other methods to accessing the gidNumber other than via ldap?
There are two ID that you can use to identify any user, the first one is the email address ( that could be changed but Google API's use to recognise a userKey ) and then is the ID for a user, which can be get if you run the Admin SDK using as Userkey from a user that you know the email address.