Iranian who live in Italy needs visa for short term to go to China

I am an Iranian student here in Milan (hold Iranian passport), Italy since 2008, and hold residence permit of Italy, I plan to go to Shanghai to attend a conference and workshop for two weeks, as I submitted a paper I will receive my formal invitation letter in a while, I wonder if I can apply here in Milan for the visa and I wonder if I have to apply for tourist or business visa (via my invitation letter which means business or via a travel agency for tourist visa )
the accommodation will cover by the institute which hold the conference so I shall I enclose that to my documents as well?
what else I will need?