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Network Working Group                                      M. St. PierreRequest for Comments: 1625                                    WAIS, Inc.Category: Informational                                       J. Fullton                                                                   CNIDR                                                               K. Gamiel                                                                   CNIDR                                                              J. Goldman                                                 Thinking Machines Corp.                                                                B. Kahle                                                              WAIS, Inc.                                                                J. Kunze                                                             UC Berkeley                                                               H. Morris                                                              WAIS, Inc.                                                        F. Schiettecatte                                                           FS Consulting                                                               June 1994WAIS over Z39.50-1988Status of this Memo   This memo provides information for the Internet community.  This memo   does not specify an Internet standard of any kind.  Distribution of   this memo is unlimited.1. Introduction   The network publishing system, Wide Area Information Servers (WAIS),   is designed to help users find information over a computer network.   The principles guiding WAIS development are:         1. A wide-area networked-based information system for searching,            browsing, and publishing.         2. Based on standards.         3. Easy to use.         4. Flexible and growth oriented.   From this basis, a large group of developers, publishers, standards   bodies, libraries, government agencies, schools, and users have been   helping further the WAIS system.   The WAIS software architecture has four main components: the client,   the server, the database, and the protocol.  The WAIS client is a   user-interface program that sends requests for information to local   or remote servers.  Clients are available for most popular desktop   environments.  The WAIS server is a program that services clientIIIR Working Group                                              [Page 1]

RFC 1625                 WAIS over Z39.50-1988                 June 1994   requests, and is available on a variety of UNIX platforms.  The   server generally runs on a machine containing one or more information   sources, or WAIS databases.  The protocol, Z39.50-1988, is used to   connect WAIS clients and servers and is based on the 1988 Version of   the NISO Z39.50 Information Retrieval Service and Protocol Standard.   The goal of the WAIS network publishing system is to create an open   architecture of information clients and servers by using a standard   computer-to-computer protocol that enables clients to communicate   with servers.   WAIS development began in October 1989 with the first Internet   release occurring in April 1991.  From the beginning, WAIS committed   to use the Z39.50-1988 standard as the information retrieval protocol   between WAIS clients and servers.  The implementation is still in use   today by existing WAIS clients and servers resulting in over 50,000   users of Z39.50-1988 on the Internet.2. Purpose   The purpose of this memo is to initiate a discussion for a migration   path of the WAIS technology from Z39.50-1988 Information Retrieval   Service Definitions and Protocol Specification for Library   Applications [1] to Z39.50-1992 [2] and then to Z39.50-1994 [3].  The   purpose of this memo is not to provide a detailed implementation   specification, but rather to describe the high-level design goals and   functional assumptions made in the WAIS implementation of Z39.50-   1988.  WAIS use of Z39.50-1992 and Z39.50-1994 standards will be the   subject of future RFCs.3. Historical Design Goals of WAIS   As an aid to understanding the original WAIS implementation and its   use of Z39.50-1988, the historical design goals of WAIS are presented   in this section.  Included with each goal is a brief description of   the assumptions used to meet these design goals.         1. Provide users access to bibliographic and non-bibliographic            information, including full-text and images.   Because Z39.50-1988 grew out of the bibliographic community,   additional assumptions with the protocol were required to serve non-   bibliographic information.  They were also necessary to serve   documents existing in multiple formats (e.g., rtf, postscript, gif,   etc.).         2. Keep the client/server interface simple and independent of            changes in the functionality of the server.IIIR Working Group                                              [Page 2]

RFC 1625                 WAIS over Z39.50-1988                 June 1994   To achieve this, the text string entered by the user was transmitted   to the server without parsing the string into a Type-1 RPN (reverse-   polish notation) query, as is common for bibliographic applications.   Instead WAIS defined a new Type-3 query containing the text string.   In this way, knowledge of the Z39.50 Attributes supported by the   server was no longer required by the client or the user, as is true   of many existing Z39.50 implementations.  In addition, the client   software did not require modification to support the evolving   functionality of the server.         3. Provide relevance feedback capability.   Relevance feedback is the ability to select a document, or portion of   a document, and find a set of documents similar to the selection.   WAIS included documents used in relevance feedback as part of the   Type-3 query.         4. Permit the server to operate in a stateless manner.   A WAIS server was designed to be "stateless", meaning that search   result sets were not stored by the server.  In Z39.50 terms, the   server exercised its right to unilaterally delete a result set as   soon as it sent the search response.  For this reason, the Present   Facility of Z39.50 was not used, and retrievals were performed using   the Search Facility.  Relaxing this constraint in future   implementations may prove the most prudent path.         5. Provide the ability for a client to retrieve documents in            pieces.   Because retrieval of a portion of a document could be done several   ways with Z39.50-1988, specific assumptions were made to implement   this functionality.  Accessing a portion of a document was required   for both retrieval and for relevance feedback.         6. Run over TCP.   The Z39.50-1988 standard was designed to run in the application layer   using the presentation services provided by the Open Systems   Interconnection (OSI) Reference Model.  Due to the popularity of   TCP/IP and the Internet, WAIS was designed to run over TCP.  Use of   Z39.50 over TCP is described in [4].4. WAIS Implementation of Z39.50-1988   By working with the Z39.50 Implementors Group (ZIG), the WAIS   developers used a recommended subset of Z39.50-1988 and specific   assumptions to fulfill its requirements.  Over time, many of theseIIIR Working Group                                              [Page 3]

RFC 1625                 WAIS over Z39.50-1988                 June 1994   requirements have then gone into the definition of subsequent   versions of Z39.50.  As new requirements become apparent, WAIS will   document any additional assumptions and work with the ZIG in   developing extensions.   WAIS supported the Init and Search Facilities of Z39.50-1988.  Both   search and retrieval were implemented using the Search Facility, as   described in this section.   Search was initiated by the client with a Search Request APDU   (Application Protocol Data Unit) using a Type-3 query.  The query   contained two main fields:         1. The "seed words", or text, typed by the user.         2. A list of document objects, where a document object is a            full document, or portion thereof, to be used in relevance            feedback.  Each document object contains a document            identifier (Doc-ID) [5], type, chunk-code, and start and            end locations.  The Doc-ID and type specify the location and            format, respectively, of the document.  The chuck-code            determines the unit of measure for the start and end            locations.  Examples of chunk-codes used include            byte, line, paragraph, and full document.  If the chunk code            is a full document, the start and end locations are ignored.   A Search Response APDU returned by the server contained a relevance   ranked list of records, or WAIS Citations.  A WAIS Citation refers to   a document on the server.  Each WAIS Citation contains the following   fields:         1. Headline - a set of words that convey the main idea of the            document.         2. Rank - the numerical score of the document based on its            relevance to the query, normalized to a top score of 1000.         3. List of available formats - e.g. text, postscript, tiff, etc.         4. Doc-ID - the location of the document.         5. Length - the length of the document in bytes.   The number of WAIS Citations returned was limited by the preferred   message size negotiated during the Init.   Retrieval of a document was initiated by the client with a Search   Request APDU using a Type-1 query.  The query contained up to four   terms:         1. Term: Doc-ID            Use Attribute: system-control-number      code = "un"            Relation Attribute: equal                 code = "re"IIIR Working Group                                              [Page 4]

RFC 1625                 WAIS over Z39.50-1988                 June 1994         2. Term: the requested document format            Use Attribute: data-type                  code = "wt"            Relation Attribute: equal                 code = "re"         3. Term: the start location            Use Attribute: paragraph, line, byte      code = "wp", "wl",                                                             "wb"            Relation Attribute: greater-than-or-equal code = "ro"         4. Term: the end location            Use Attribute: paragraph, line, byte      code = "wp", "wl",                                                             "wb"            Relation Attribute: less-than             code = "rl"   Because full-text and images were often larger in size than the   receive buffer of the client, clients were designed to optionally   retrieve documents in chunks, specifying the start and end positions   of the chunk in the query.  An example of a fully-specified retrieval   query is:   query = ( ( use = "un", relation = "re", term = <Doc-ID> )             AND             ( use = "wt", relation = "re", term = postscript )             AND             ( use = "wb", relation = "ro", term = 0 )             AND             ( use = "wb", relation = "ro", term = 2000 )            )   A retrieval response was issued by the server with a Search Response   APDU. In this case a single record corresponding to the requested   document, or portion thereof, was returned in the specified format.5.  Security Considerations   Security issues are not discussed in this memo.6.  References   [1] National Information Standards Organization (NISO).  American       National Standard Z39.50, Information Retrieval Service       Definition and Protocol Specifications for Library Applications,       New Brunswick, NJ, Transaction Publishers; 1988.   [2] ANSI/NISO Z30.50-1992 (version 2) Information Retrieval Service       and Protocol: American National Standard, Information Retrieval       Application Service Definition and Protocol Specification for       Open Systems Interconnection, 1992.IIIR Working Group                                              [Page 5]

RFC 1625                 WAIS over Z39.50-1988                 June 1994   [3] Z39.50 Version 3: Draft 8", October 1993.  Maintenance Agency       Reference: Z39.50MA-034.   [4] Lynch, C., "Using the Z39.50 Information Retrieval Protocol       in the Internet Environment", Work in Progress, November 1993.   [5] "Document Identifiers, or International Standard Book Numbers       for the Electronic Age", Brewster Kahle, Thinking Machines       Corporation, see URL=<ftp://wais.com/pub/protocol/doc-ids.txt>,       September 1991.7.  Authors' Addresses   Margaret St. Pierre   WAIS Incorporated   1040 Noel Drive   Menlo Park, California  94025   Phone: (415) 327-WAIS   Fax:   (415) 327-6513   EMail: saint@wais.com   Jim Fullton   Clearinghouse for Networked Information   Discovery & Retrieval   3021 Cornwallis Road   Research Triangle Park, North Carolina  27709-2889   Phone: (919)-248-9247   Fax:   (919)-248-1101   EMail: jim.fullton@cnidr.org   Kevin Gamiel   Clearinghouse for Networked Information   Discovery & Retrieval   3021 Cornwallis Road   Research Triangle Park, North Carolina  27709-2889   Phone: (919)-248-9247   Fax:   (919)-248-1101   EMail: kevin.gamiel@cnidr.orgIIIR Working Group                                              [Page 6]

RFC 1625                 WAIS over Z39.50-1988                 June 1994   Jonathan Goldman   Thinking Machines Corporation   1010 El Camino Real, Suite 310   Menlo Park, California  94025   Phone: (415) 329-9300 x229   Fax:   (415) 329-9329   EMail: jonathan@think.com   Brewster Kahle   WAIS Incorporated   1040 Noel Drive   Menlo Park, California  94025   Phone: (415) 327-WAIS   Fax:   (415) 327-6513   EMail: brewster@wais.com   John A. Kunze   UC Berkeley   289 Evans Hall   Berkeley, California  94720   Phone: (510) 642-1530   Fax: (510) 643-5385   EMail: jak@violet.berkeley.edu   Harry Morris   WAIS Incorporated   1040 Noel Drive   Menlo Park, California  94025   Phone: (415) 327-WAIS   Fax:   (415) 327-6513   EMail: morris@wais.com   Francois Schiettecatte   FS Consulting   435 Highland Avenue   Rochester, New York  14620   Phone: (716) 256-2850   EMail: francois@wais.comIIIR Working Group                                              [Page 7]