Z39.50

Z39.50 Protocol Overview - Z39.50 is an international standard client-server, application layer communications protocol. - It is used for searching and retrieving information from a database over a TCP/IP computer network. - Developed and maintained by the Library of Congress. - Covered by ANSI/NISO standard Z39.50 and ISO standard 23950. - Widely used in library environments for interlibrary catalogue search and loan. Search Syntax - The protocol supports search, retrieval, sort, and browse functions. - Search queries contain attributes from the bib-1 attribute set. - The syntax allows for very complex queries. - Functional complexity is limited by uneven implementations by developers and commercial vendors. - Results for the same query can vary widely among different servers. Modernization Efforts - Z39.50 is a pre-Web technology. - Modernization efforts include the ZING (Z39.50 International: Next Generation) projects. - The successors to Z39.50 are the protocols SRU/SRW (Search/Retrieve via URL/Search/Retrieve Web service). - SRU is REST-based and SRW uses SOAP. - These projects have a lower barrier to entry for developers compared to the original Z39.50 protocol. Firewall Information - The registered network port number for Z39.50 is 210, but other port numbers are used worldwide. - Dozens of other port numbers are used, such as 2100, 2200, 2210, 2213, 3520, or ports 2101 and higher for different databases. Related Concepts and References - Wide area information server (WAIS) - Dynix - Koha - OpenURL - OpenSearch