The ANSI/NISO Z39.50 Protocol: Information Retrieval in the Information Infrastructure

ENHANCING THE STANDARD

While Z39.50 has been used initially for systems that manage bibliographic data (e.g., online public access catalogs), the protocol is actually quite general and extensible. In keeping with the dynamic networked information environment in which it is deployed, Z39.50 grows and expands in functionality and richness. Revisions to the standard, however, acknowledge and support the installed base of Version 2 implementations; this provides stability in the standard, compatibility between versions, and protects the investment in Z39.50 products while extending the standard's usefulness.

Based on the requirements of Z39.50 implementors and users, the current draft of Version 3 contains a number of new features and enhancements. Not all implementations will choose to support all these features, and conformance to the standard does not require support for all features. The following highlights new enhancements that will be available to implementors of Z39.50:

Sort: allows the client to request that the server sort and order a result set according to client-supplied criteria
Scan: provides the client with the ability to scan lists of terms (i.e., access point values) available from a database or a group of databases
Extended Services: defines a set of tasks or operations that the client may request the server to perform, such as: saving a result set for later use, executing search queries on a periodic schedule, exporting the records in a result set, ordering documents, and requesting printing
Explain: allows the client to obtain information about the implementation of a server system including the databases available for searching, restrictions on the use of the server, hours of operation and availability and a broad range other important information the client can use to facilitate effective information retrieval with a particular server
Segmentation: provides for the effective transfer of parts of a record when the entire record exceeds the transfer size negotiated between the client and server; this is especially critical for image databases and multimedia services
Proximity Searching: a query type (experimental in Version 2) that enables a client to specify proximity searching
New Record Syntaxes: defines several new record syntaxes that the target can use to package database records for transfer to the origin including:
- Simple Unstructured Text Record Syntax (SUTRS) -- intended for textual data and allows the origin to display the retrieved data with little or no processing;
- OPAC Record Syntax -- includes holdings and circulation data; Generic Record Syntax (GRS) -- a general-purpose format for packaging records of varying complexity with potentially arbitrary data in individual fields.

It is anticipated that as Z39.50 is developed further it will support information retrieval related services such as document delivery and offer new flexibility in the range of information that can be handled by the standard.