Is it common and/or acceptable to have Ajax requests every time a button is clicked on a shopping cart page? This is not a high traffic site. It will only have a few users at a time, like 5 max. I'm calling it a shopping cart for lack of a better term. The site is intended to let customers create highly customized orders, which benefits from logic being on the server instead of on the client.
I have many questions regarding the best practices in this sort of design. Like, should I block user input until the ajax request is received? Should I be sure to display an error message if the ajax request fails? Should I automatically repeat the ajax request if it fails? Are there any other considerations?