General ASDD Z39.50 configuration issues

Overview

The ASDD search and retrieve overview explains ASDD Z39.50 search, retrieve, and present. Please read that for background understanding. The ASDD documentation and resources technical index page has high-level definitions of some technical terms.

The main components of the Z39.50 solution are briefly described below.

The requirements for establishing an ASDD node are concisely summarised in the document Requirements and Standards while the document Implementing new ASDD nodes provides the detail. Essentially, the ASDD nodes need to run a Z39.50 server that responds correctly (according to the GEO Profile) ... responds to Brief and Full Element Sets and to Record Syntaxes (HTML, XML, SUTRS) and delivers geospatial metadata according to the ANZMETA XML Document Type Definition (DTD).

Z39.50 Profiles

A profile identifies a set of base standards, together with appropriate options and parameters necessary to accomplish identified functions for purposes including: (a) interoperability, and (b) methodology for referencing the various uses of the base standards, meaningful both to users and suppliers. [from Z39.50 Maintenance Agency: About profiles]

See more information about Z39.50 profiles in general. However, that is only for further reference. These ASDD technical pages will provide sufficient information.

Essentially your Z39.50 server, and its configuration, must comply with the GEO Profile (and optionally the GILS and BIB-1 Profiles). Note that your server is probably already pre-configured to handle all of this. If it is not, then you may need to consult these documents.

• GEO Profile - "Z39.50 Application Profile for Geospatial Metadata (GEO)" version 2.2
• GILS Profile - Global Information Locator Service
• BIB-1 Profile - for bibliographic information

Z39.50 Attribute Sets

Z39.50 queries are composed by a client or gateway using "Attribute Types", "Attributes", and search "Terms". Here are the Attribute Types ...

1. Use attributes - which field to conduct the query against (4=title, 62=abstract, ...)
2. Relation attributes - the relation of the search term to the use attribute (greater than, less than, equal to, ...)
3. Position attributes - the position within a field/subfield (first data in field, any, ...)
4. Structure attributes - whether the search term is a word, a phrase, a date, etc
5. Truncation attributes - use truncation when searching the index (right, left, ...)
6. Completeness attributes - whether the term must be the only data in the field

From the point of view of configuring a Z39.50 server, the most important attribute type is the "Use Attribute". For example, the ASDD Isite has a simple "Use Attribute" configuration file. This file maps the Use Attributes (the field numbers behind the WWW interface pick-lists) to the actual field names in each document collection. For example, Use Attribute number 4 is mapped to the ANZMETA metadata element "title" and Use Attribute number 62 is mapped to the ANZMETA metadata element "abstract". In this way the standard Z39.50 Use Attributes (numbers that are well-understood by all clients and servers) can be mapped to any back-end information system. Z39.50 insulates the user from the actual schema (structure and field names) of each document management system.

The other important attribute types are usually handled internally by your server. However, with some brands of Z39.50 software you may need to configure them. If you are building your own client or gateway then you will certainly need to know them.

Here are direct links to some of the relevant appendices of the GEO Profile standards document ...

• Use Attributes - However, remember that the GEO Profile is largely geared towards the US FGDC metadata. Australian metadata has far fewer Use Attributes. The Isite configuration files (see above) shows the Use attributes for Australia.
• Relation Attributes
• Structure Attributes
• GEO Attribute combinations

The GEO Profile adopts many of the BIB-1 attributes and some GILS attributes. For further explanation, see the GEO Profile.

Element Sets

"Element Sets" allow the client to specify which elements from a metadata record should be presented ...

• B ... Brief
  • show only the TITLE element
  • the ASDD gateway requests this to present the list of results
• F ... Full
  • show the full data set description, i.e. all elements

There are also optional element sets called "S" for Summary which provides a selection of useful elements and "R" for Resource which provides specific linkage elements to link to other resources.

Record Syntaxes

The "Record Syntax" specifies the format in which the client wants to see the metadata ...

• HTML - for presentation via WWW browsers.
• SUTRS (Simple Unstructured Text Record Syntax) - plain text, could have some informal structure. Some clients from the library world will request this. Note that it has no specified format, and is just what it says - unstructured text. However, a suitable format would be colon-tagged element names and 72 character line width with long paragraphs wrapped into multiple lines.
• XML - for modern information systems. As specified by the ANZLIC Metadata Guidelines, the XML (according to the ANZMETA DTD) is the prime format for the metadata record. The other Record Syntaxes are presentation forms.

Each ASDD node should be capable of responding to these three Record Syntaxes. Ideally, your server should also respond to the GRS-1 Record Syntax.

Further information

If you are implementing your own client software or gateway, then you will need further information. The detail of the GEO Profile is still your main resource. Here are some others ...

• Z39.50 Maintenance Agency
• Z39.50 Object Identifiers (OID)
• www.z3950.org