Seventh Heaven: The Transfer Protocols

There are many Internet-scale messaging systems: Telnet for duplex byte streams, File Transfer Protocol (FTP) for pulling files, Simple Mail Transfer Protocol (SMTP) for reliable e-mail messaging, Network News Transfer Protocol (NNTP) for pushing e-mail, HyperText Transfer Protocol (HTTP) for pulling Web pages, and a host of other special-purpose schemes, from Finger to Network File System (NFS). How can we make sense of it all? Understanding the history of these transfer protocols (TPs) is the key to charting their future, especially as new contenders like HTTP-NG (next-generation) emerge. In this article, I set forth a general ontology-a vocabulary for describing and classifying TPs, with the aim of developing a framework to help navigate among the alternatives.