I do it all the time in chat. I'll say, Good Morning [name], and wait for them to respond. It seems rude to me to just blurt out what I want. If I walked up to someone in an office whom I don't normally speak with, I would first say, "Hi. How are you?" and wait for them to respond. At the very minimum, I would say hi and wait for them to say, hi back before I tell them what I'm looking for. Same thing over chat.