B protocol
From Wikipedia, the free encyclopedia
CompuServe B protocol, also known as CIS B+, is a file transfer protocol developed by the commercial online service CompuServe in 1979. The protocol was only available to members of CompuServe.
Contents |
[edit] Technology
[edit] Transferring files
B protocol was completely host-driven, meaning that an FTP client was not required to use the protocol. You only needed to be logged in as a member of the CompuServe system, and you could initiate file transfers between your and another member's computer. The protocol also featured error detection and correction technology that allowed for more reliable transfers. The process was as follows:
- Your computer contacted the CompuServe host and notified it that you had a file to send.
- The host located the recipient's computer and verified that they were also a CompuServe member.
- The host sent a special Enquiry command (CTRL-E) to your computer that initiated the transfer of your file to the host.
- The host sent another Enquiry command to the recipient's computer that initiated the transfer of your file to the recipient.
If the recipient was on online at the time of the transfer, they would be notified the next time they logged in that a file transfer was waiting for them.
[edit] Compatibility
Since B protocol was designed only to work within the CompuServe Information System, most communications clients of the day were not compatible with it. One notable exception was Datastorm's ProComm Plus, which featured the ability to listen for the Enquiry command on your active communications port. This development was part of a wider trend of using external communications applications in conjunction with online services.
[edit] Future development
A protocol named "Quick B" later evolved from B protocol and could only be used for downloads. It was much faster, and would be selected as the default file transfer protocol for CompuServe users of the time.
