married to canadian but she is a resident of china

hi pls i will like to get a solution to this as i am very confused as what to do.
my wife is a canadian i am from southafrica both of us married on december 2011
in cape town south africa but my questions are is my wife as a resident of china able to give me invitation to take visa from chinese embassy?and will she be able to endorse our marriage certificate in china? any advce will be appriciated. cheers