I'm developing eBay Sinatra application and need to authenticate an user by their login and password to give them the ability to request their information from eBay by themself. By authentication I mean authentication by redirection (or something like) to eBay and entering their login and password. It's similar to Facebook authentication.
I did a research but found almost zero. Your suggestions?
Omniauth has a strategy for ebay authentication. I haven't used it but omniauth is a competent gem for handling different login strategies for various sites out there. Recently I have used omniauth with rails but a couple of months ago I did likewise with padrino so I think it should work nice with pure sinatra also.