Data exchange protocols
Any information exchange requires a set of conventions shared by the sender of a message and its recipient: both must know when the communication begins, what procedure it follows, and when it ends. Such sets of conventions are called protocols.
Several protocols enable machines to exchange bibliographic data or metadata.
Description of Z39.50 protocol
International standard ISO 23950: Information Retrieval (Z39.50), dating back to the 1980s. This is the oldest data exchange protocol, still widely in use in libraries.
This protocol, developed in 1999, was originally designed to meet the needs of publishers of digital scientific publications. Its use was then extended to libraries.