ABSTRACT
In the 1970s, a number of library leaders, such as Henriette Avram at the Library of Congress and the developer of the machine-readable catalog record (MARC), envisioned the convergence of computing and telecommunications that would enable machine-to-machine communication for accessing bibliographic and other types of information. Initial work on intersystem communication focused on connecting large bibliographic databases such as those at the Library of Congress, the Online Computer Library Center (OCLC), and the Research Libraries Group (RLG). Making this vision a reality required the development of standard protocols for intersystem communication. Protocols specify rules for communication including what information can be exchanged, in what format, and in what order. Thirty years later, the networked information landscape has changed dramatically, but the need still remains for standard protocols that support information retrieval (IR) transactions (e.g., sending a query and receiving the results of the executed query) against a range of databases or systems. Standards development work through the 1980s and 1990s yielded the ANSI/
Introduction .................................................................................................................................... 629 IR .................................................................................................................................................... 630 Communications Protocols............................................................................................................ 631 The Z39.50 IR Protocol................................................................................................................. 632
A Brief Chronology of Z39.50 Development........................................................................... 632 Z39.50 Protocol Details ............................................................................................................ 633
Init Service ........................................................................................................................... 634 Search Service...................................................................................................................... 634 Present Service..................................................................................................................... 636
Interoperability and Intersystem IR............................................................................................... 636 A Next Generation Z39.50 ............................................................................................................. 637 SRW ............................................................................................................................................... 638
Protocol Operations and Examples........................................................................................... 638 searchRetrieve Operation..................................................................................................... 639 Explain Operation.................................................................................................................640
