You have to go into the past a little bit. Think about your:
University email, FTP, and terminal server.
The Internet is just a highway. You will end up at a destination.
University email, FTP, and terminal server.
The Internet is just a highway. You will end up at a destination.
Email protocol suite is designed to be federated. FTP is just a file system access protocol. But you could combine it with an inter-server filesystem synchronization protocol/service to make it a distributed federated service. And as for terminal servers,.. well, I don't think centralization makes much sense there. How can you achieve any of these with centralized services?
Again i talk about the past when email was primarily used to talk to other peoples often not even over a net but inside a mainframe thing.
I though i was clear talking about the past hence not including Facebook or GitHub, and btw. Email just became "federated" when everyone agreed to use smtp when talking over the internet.