family visit L for my parents from Sri Lanka

I am married to Chinese from Sri lanka and writing to you from Shanghai. Kindly may I know the visa requirements for our parents in Sri lanka to visit us as family L visa this is there first time to visit my wife parents and family. So far I know is that my wife will write a invitation letter other than this what are the documents our parents must keep ?

1. Application
2.iniviation letter
3.bank statements
4.our marriage certificate
5.my wife ID copy

Is this all ?

And our parents plan to come with us together when we arrive to Sri lanka for holiday so our parents will submit the applications and if the embassy need to know anything can contact my wife as I have given her phone number too.

Thank you sir and staff,
Chris.