About library search services

Introduction

The Eco Companion search services are the same as those used in many online library information systems. These facilities use the Z39.50 search and retrieve protocol.

This means that the documents that are managed and published by members can then be discovered through many avenues. Users can either search using Eco Companion services, or they can search using virtual digital libraries that conduct simultaneous searches at many distributed servers.

Eco Companion is a node of the distributed Australian Spatial Data Directory (ASDD). Simultaneous search for geospatial dataset descriptions at many directories.

What is the Z39.50 protocol

The need of the early digital libraries to share bibliographic information led to the development of the Z39.50 protocol. Modern information systems can now be implemented using sophisticated gateways between the HTTP protocol of the WWW and Z39.50 protocol of library worlds. They can also utilise the capability to conduct a distributed query to many information servers.

"Z39.50 is an ANSI standard which describes a protocol which enables you to search and retrieve information in a variety of information resources using your preferred user interface (client). When Z39.50 is implemented properly you don't even know you are using it. This is a good thing!!!!" [from Z39.50 UNLEASHED (Internet Trends)]

Z39.50 provides field-level and full-text query of attributes and can conduct stateful sessions. ANSI Z39.50 is now internationally recognised as ISO 23950.

Sophisticated search services

Z39.50 services are capable of sophisticated searching:

• full-text
  • every word in each document is indexed
• text fields
  • structured documents have separate fields: Abstract, Keywords, etc.
  • searches can be constrained to certain fields
• spatial
  • using a geographic window
  • north, south, east, west coordinates of a minimum bounding rectangle (MBR)
  • within, overlapping, encompassing
  • bounding polygon would be desirable, but is not yet possible
• temporal
  • dates within a range
  • dates within a number of days of the present
  • before, after, equal to a certain date
• numeric
  • geographic coordinates
  • postcode
  • use numeric operators, such as: >, =, <=
• boolean operators
  • AND ... the query "solar AND energy" will find only documents that contain both words.
  • OR ... the query "solar OR wind" will find only documents that contain either word (as well as both words).
  • ANDNOT ... the query "solar ANDNOT wind" will find only documents that contain the word "solar" but do not contain the word "wind". ANDNOT is the complement of AND.
• phrase
• proximity
• truncation and wildcards
• distributed searching
  • searches can be conducted simultaneously at a number of distributed Z39.50 servers
• query languages are used to precisely define the query
  • usually a user-interface will compose this behind the scenes
  • advanced interfaces allow you to compose your own complex query
• intelligent agents can conduct automated searches
  • your server could automatically send off a robot to specific nodes every night to conduct a query that you have configured, you could specify "datasets published yesterday, theme keyword: marine biology" and read the results as an HTML page when you are ready in the morning

Canned example searches

See the document "Canned example searches" which has some prep-prepared example searches that you can run simply by selecting the hypertext links on the page.

URL:http://www.indexgeo.com.au/ec/about/search.html
Last Modified: 21 November 1998