Published on Brock University (http://www.brocku.ca)
If your family or friends wish to visit you in Canada for your Convocation or just for a vacation, they need to apply for a Temporary Resident Visa (TRV) at their closest Canadian Consulate. For a list of countries whose citizens require a TRV to enter Canada, please visit the Citizenship and Immigration Canada's website at: http://www.cic.gc.ca/english/visit/visas.asp ). For full instructions on how the apply for a TRV, please visit: http://www.cic.gc.ca/english/information/offices/missions.asp 
On the Canadian Consulate's visiting visa instruction page, you will find list of documents required from the "applicant" (the person you are inviting), and from the "inviter"(you).
In order to assist your family/friends with their TRV application, you should send them the following supporting documents:
All the above are generally required by Canadian Consulates overseas for "inviters". There could be more detailed instruction from local responsible visa offices. It is very important that you check that local Canadian Consulate's website and follow the full instructions.