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The following technical terms and acronyms are used somewhere in the Eco Companion service. You will not need to understand these terms to use the Eco Companion catalogue. However, the explanations here will give more insight.
The definitions provided here are in the context of the fields of resource discovery and geospatial information retrieval. They are intended to assist users of the Eco Companion document management service.
Other useful online dictionaries and glossaries:
Various organisations and individuals in the Australian and New Zealand spatial data communities have been working together over the last few years to implement co-ordinated nationwide approaches to the management, consistency, and availability of spatial data resources in this region. Lead organisations are Australia New Zealand Land Information Council (ANZLIC), the Australasian Urban and Regional Information Systems Association (AURISA), the Institution of Surveyors Australia (ISA).
"The primary objective of a national spatial data infrastructure is to ensure that users of land and geographic data who require a national coverage, will be able to acquire complete and consistent datasets meeting their requirements, even though the data is collected and maintained by different jurisdictions." [from Spatial Data Infrastructure for Australia and New Zealand - A Discussion Paper by Australia New Zealand Land Information Council (ANZLIC)]
The ANZLIC Strategic Plan 1997-2000 defines how the ASDI will be achieved.
See also the ASDI home page at AUSLIG.
"ANZLIC's mission is to provide leadership for effective management and use of land and geographic information to support economic growth, sustainable development and the social and environmental interests of Australia and New Zealand."
"ANZLIC's vision is that Australia and New Zealand will have the land and geographic data infrastructure needed to support their economic growth, and their social and environmental interests, backed by national standards, guidelines, and policies on community access to that data."
At the ANZLIC home page you will find many useful documents, including:
A browser is a client program (software) on your desktop computer that you use to "browse" through the many and varied document collections on the network. A browser also enables a server computer (at the other end of the connection) to present you with interactive interfaces with which to conduct searches of the databases held by the server.
A consistently organised collection of concise resource descriptions that is used to search for and discover relevant resources.
A catalogue is not the actual resources themselves, rather it is a list of notes that describe certain resources.
The catalogue record will then give give you information about the resource, metadata (data about data) such as: the name of the author, the title of the document, the date that it was published, how and where to find the actual resource. The catalogue record will often link directly to the resource that it describes.
A "directory" is another name for a catalogue.
A client is a software program designed to interact with specific server programs using accepted protocols.
You use the client, on your desktop computer, to prepare and specify a request. Your client then sends the request across the network connection to the server. The server program then carries out the relevant actions, packages the results, and sends them back. Your client then takes over and presents the results.
Clients talk with servers. Servers wait for, and conduct, requests from clients.
Some clients, such as WWW browsers, can also enable the server to present a gateway interface to other protocols, for example between the HyperText Transport Protocol of the WWW and the Z39.50 protocol of online library worlds.
Some server programs can also act as clients and request actions of other servers.
"Pairs of numbers expressing horizontal distances along orthogonal axes, ... expressing a precise location in n-dimensional space. Co-ordinates generally represent locations on the earth's surface relative to other locations." [from GIS Dictionary]
Latitude and longitude is a co-ordinate system.
See Eco Companion service Produce a locality map to plot coordinates on a basemap.
A dataset is a particular coherent collection of data with a common theme.
It might be a collection of photographs at a certain location or on a certain subject, a map, records of geological borehole samples, a database comprising records of pollution sites, a scientific report, a listing of results from a school project.
A dataset need not only be in digital form. A paper publication, or report, or collection of maps are also datasets.
Geospatial datasets are collections of spatial data that has reference to a location in earth-centred space.
A dataset description is a concise document that describes a dataset.
The dataset description document is well-defined and structured using elements of metadata (data about data). It is analogous to a card in the catalogue of your local library which describes the books and gives enough information to know what the book is called, its unique number, how and where to find it. These details are metadata - bibliographic elements such as Author, Title, Abstract.
Geospatial dataset descriptions describe spatial data that has reference to a location in earth-centred space.
A consistently organised collection of concise resource descriptions that is used to search for and discover relevant resources.
See the definition of the term "catalogue", which is another name for a "directory" .
The term refers to the many aspects of creating, editing, and publishing documents -- then keeping them up-to-date so that they are always relevant.
The process of document management involves authors, editors, software facilities, publishing and promotion
- Authors create documents, add content, and refine it.
- Editors oversee the documents to ensure that they have relevant content and contain useful search terms.
- Software facilities enable authors and editors to easily and consistently manage the documents. These facilities ensure that documents are generated to current digital library standards and so enables better resource discovery.
- Publishing, which includes document management, is the process of accepting the authors work, assisting to refine the content, and making the document publicly available.
- Promotion results in the documents having better exposure. It involves ensuring that the catalogue itself is well-known and that the documents can be discovered through many avenues.
When documents are personally maintained, then they are given dedicated attention. They will be more likely to have relevant and useful content.
Using controlled document storage and generation methods, the documents will be well-structured and contain elements of metadata, which concisely describe the document itself. This enables digital library catalogues to accurately index the information.
Online document management facilities, such as Eco Companion, relieve the author of the need to maintain such software on their own computer -- a time-consuming and expensive process.
We can update the facilities of the service at any time to ensure that your documents are always generated using the best available methods. Your documents will be more likely to rank highly with the many public search facilities, as well as in the Eco Companion catalogue.
Document management promotes resource discovery.
To ensure that all dataset descriptions are of a consistent type, the Document Type Definition (DTD) defines the metadata elements, and their order, structure, and relationships. The DTD is one component of the SGML document management solution.
A DTD allows different instances of documents of the same type to be automatically processed in a uniform way.
"The type of a document is formally defined by its constituent parts and their structure ... a special purpose program (called a parser) can then be used to process a document, claiming to be of a particular type, and check that all of the elements required for that document are indeed present and correctly ordered." [from A Gentle Introduction to SGML]
The ANZMETA DTD defines geographic dataset descriptions for Australia and New Zealand.
A gateway is a program on a server computer that provides access to resources that cannot be directly read by the client because they are in format that the client does not understand.
Clients are purpose-specific software programs that carry out a dialogue with a server using a particular protocol (rules of communication), for example WWW browser clients talk to WWW servers using the HyperText Transport Protocol (HTTP). If the client wants to access resources in a different realm (such as online libraries), then the server gateway handles the conversion between the two different protocols. The client program does not need to understand anything about the protocol on the other side of the gateway.
"Information about objects or phenomena that are associated with a location relative to the surface of the Earth. A special case of spatial information." [from GIS Dictionary]
Spatial data that has reference to a location in earth-centred space.
The field of "information retrieval" is concerned with the many aspects of the management, publishing, promotion, searching, discovery, access, and retrieval of information. "Geospatial information retrieval" refers to the discovery of, and access to, spatial data and information that is specifically related to earth-centred space.
The document format used for text documents on the World Wide Web. The language specifies the various elements of the layout and presentation of the document.
HTML is an application of the Standard Generalised Markup Language (SGML) which is widely used in the document management and network publishing fields.
"Hypertext" allows words and phrases in a document to be highlighted, to create links to other documents using Uniform Resource Locators (URLs).
You use your browser program on your desktop computer to navigate though a collection of HTML documents by selecting the marked hypertext links. The browser reads the layout commands of the various HTML elements and renders the document on your screen accordingly.
Further information:
- HTML Code Tutorial - Idocs guide to HTML
- The Bare Bones Guide to HTML
- Working and Background Materials at the World Wide Web Consortium (W3C)
A worldwide co-ordinate system used to define the location of points on the earth's surface.
- Latitude is the angular distance north or south of the equator
- expressed as decimal degrees in the range: -90 at the south pole, through the southern hemisphere to 0 at the equator, through the northern hemisphere to +90 at the north pole
- Longitude is the angular distance east or west of the prime meridian at Greenwich Observatory in London
- expressed as decimal degrees in the range: -180 at the antipodes of Greenwich meridian, through the eastern hemisphere to 0 at Greenwich meridian, through the western hemisphere to +180 at the antipodes of Greenwich meridian again.
See further explanations. Use these services to find the latitude and longitude of a location. Create a world map showing a particular location.
The action of providing your user credentials (username and password) so as to connect to a computer that provides services that are restricted to registered users.
Login does not mean that your browser stays connected to the server computer. As with all WWW connections, the server sends the document back to the client, disconnects, and then goes on to serve the next client. The server has sent your client a special code so that it can recognise you when you request another document.
With Eco Companion, the login procedure does not incur any charges, it is simply a method to ensure valid users and that each member's documents are protected from editing by anyone but the relevant member. There is no need to ever "logout".
Data about data. Describes the data, but is not the actual data itself.
The records in a card catalogue in a local library give brief details about the actual book. You are given enough information to know what the book is called, its unique number, how and where to find it. These details are metadata - bibliographic elements such as Author, Title, Abstract.
Dataset description documents use elements of geospatial metadata to describe specific collections of spatial data (datasets).
Metadata has many uses, including:
- concisely describe datasets and other resources
- using elements such as: the name of the dataset, the quality, who is the custodian, how to access the data, what is its intended purpose, who to contact for more information about the data
- enable effective management of resources
- enable accurate searching and resource discovery
- provide an online interface to a dataset and link to other information about it
- a record in a searchable catalogue of datasets
- search software will index each dataset description document, using the words in each metadata element, to create a database that can be searched using keywords
- accompany a dataset when it is transferred to another computer so that the dataset can be fully understood, and put to proper use, and so that custodians are duly acknowledged
Metadata records are resource descriptions. See more explanation about metadata.
The spatial extent (geographic coverage) of a dataset is defined by a rectangle. This will express the limits of coverage of the dataset as four geographic co-ordinates - north and south latitude, east and west longitude.
The official Australian Geographic Extent Names (GEN) each have an associated MBR. See the authority lists of GENs.
See Eco Companion service for plotting Australian MBRs on basemaps to show the location of a particular defined Australian GENs.
A parser is a computer program that reads a text document and distinguishes all of the separate elements found in the document. It can also determine the relationships between elements of the document.
The parser needs an associated Document Type Definition to know what to look for as it reads the document sequentially from beginning to end.
A protocol is a particular set of accepted rules of communication that computers use to carry out a consistent dialogue over a telecommunication connection. The protocol allows each end of the connection (the client and the server) to understand, and correctly respond to, what the other computer is saying.
Some widely-used protocols are:
- FTP ... File Transfer Protocol
- HTTP ... HyperText Transport Protocol
- used to transfer HTML documents of the World Wide Web
- SMTP ... Simple Mail Transport Protocol
- used to transfer electronic mail
- Z39.50 ... information search and retrieve protocol
- enables distributed digital libraries and sophisticated search and discovery
"To issue to the public the works of an author" [Macquarie Dictionary]
The publishing process includes many aspects, including: assist the author to prepare and create their work, edit the work to ensure that it is fit for consumption by the target audience, make the work available to the public, promote the work so that it reaches a wider audience, issue revisions and updates of the work.
Resources are works that have been published.
Every unit of data or information that is available on the network is a "resource". There are many forms: WWW pages, images, text documents in various formats, movies, databases, sound files, photographs, programs, spreadsheets, bibliographies, interactive Internet services.
Resources can be static (such as documents) or dynamic (generated by a computer program).
Resources are uniquely named using Uniform Resource Locators (URLs)
A "resource description" is a concise document that describes another document (or resource) using elements of metadata (data about data).
Resource descriptions serve as records in a searchable catalogue. They concisely describe the resources, so then the searching facilities can more readily find relevant documents. They enable effective resource discovery.
The World Wide Web Consortium (W3C) is developing the Resource Description Framework (RDF) to consistently describe resources on the Internet. The Dlib Magazine article "An introduction to the Resource Description Framework" by Eric Miller provides an excellent overview.
The discipline of information technology that is concerned with all aspects of finding, locating, and retrieving resources that are relevant to the user who is conducting a search.
Resource Discovery - A Definition is provided by the Resource Discovery Unit (RDU) of the Distributed Systems Technology Centre (DSTC).
A server is a computer that performs tasks and provides services to other computers.
You use a client software program, on your desktop computer, to prepare and specify a request. Your client then sends the request across the network connection to the server. The server program then interprets the query, carries out the relevant actions, packages the results, and sends them back. Your client then takes over and presents the results.
Clients talk with servers. Servers wait for, and conduct, requests from clients.
The term "server" can also refer to a software program. A single server machine can simultaneously run many different server programs, such as WWW servers, an e-mail server, and an FTP server.
Some server programs can also act as clients and request actions of other servers.
Server programs can also be gateways between different protocols, for example between the HyperText Transport Protocol of the WWW and the Z39.50 protocol of online library worlds.
Spatial means "pertaining to space". This term is often used instead of "geographic". However, geographic means "pertaining to geography (the study of the surface of the earth)" and "referring to or characteristic of a certain locality, especially in reference to its location in relation to other places" [Macquarie Dictionary]. Spatial has broader meaning, encompassing the term geographic.
Data that has, among its attributes, a reference to a location in space.
"Any information about the location and shape of, and relationships among, geographic features ..." [from GIS Dictionary]
The Commonwealth Spatial Data Committee (CSDC) addresses spatial data issues affecting the Commonwealth of Australia.
The methods used in the document management and publishing field.
"The Standard Generalised Markup Language (SGML) is an international standard for the definition of device-independent, system-independent methods of representing text in electronic form. SGML is a metalanguage, that is, a means of formally describing a language." [from A Gentle Introduction to SGML]
"SGML is necessarily sophisticated: It is providing a much-needed service by allowing the exchange of information at any level of complexity among software, hardware, storage and presentation systems (including database management and publishing applications) without regard to the manufacturer's name on the label. And it is doing all this with the authority of an International Standard." [from Introduction to the SGML PRIMER]
At its very basic form, SGML describes particular elements of text with easily recognisable nametags in opening and closing pairs. These elements can be parents and children, thus describing a hierarchical, structured relationship between the elements of a document.
<document> <title>My Life</title> <author>Fred Nerk</author> <abstract>Not much</abstract> </document>The Eco Companion service stores documents as SGML/XML files and uses parsers and Document Type Definitions to process the documents.
To find out more about SGML, read A Gentle Introduction to SGML and find many resources at the The SGML/XML Web Page.
Client and server computers communicate with each other across a network connection using a particular protocol (rules of communication). When the server remembers each request from the client, then the server has maintained the "state" of the conversation.
- HTTP (HyperText Transport Protocol) of the WWW is a stateless protocol
- When your browser requests a WWW server to return a document, then your client sends a small message to the server. The message simply tells the server the name of the document and the network address to send it back to. The server sends the document, then forgets who you are, and serves another client.
- Z39.50 protocol of online libraries is a stateful protocol
- When you connect to a Z39.50 server then a session is established. The server assigns your client an identification number and creates some files to hold the history of your session by logging each query. When you conduct a query, then the server remembers the results so that you can request the next 20 documents when you are ready. If your client is idle for some time and does not send any more queries, then the server decides that you are finished and terminates the connection (timeout).
Uniform Resource Locators (URLs) are a scheme to assign unique names to resources on the Internet. This scheme gives a uniform way to refer to, access, and retrieve the resource. Resources are documents, programs, files, images, etc.
The URL of this glossary page is http://www.indexgeo.com.au/ec/about/glossary.html
It is composed of three basic parts:
- http:// ... the protocol or method used to access the resource, in this case HTTP (HyperText Transport Protocol)
- www.indexgeo.com.au ... the Internet name of the computer that holds the resource
- /ec/about/glossary.html ... the pathname of the document, giving the name of the file and the hierarchical folders that contain it. The filename extension (.html) often indicates the type of document.
- well-structured documents that conform to a set of rules
- separates the structure and content from the formatting and presentation
- plain text documents that are independent of software, vendors, proprietry formats, and computing platforms (XML documents live longer)
"XML itself is not a single markup language: it's a metalanguage to let you design your own markup language. A regular markup language defines a way to describe information in a certain class of documents (eg HTML). XML lets you define your own customized markup languages for many classes of document. It can do this because it's done in SGML, the international standard metalanguage for markup languages." [from the XML Frequently Asked Questions]
The SGML/XML Web Page covers everything to do with SGML and XML.
Z39.50 is the information search and retrieve protocol which defines the interactions between client and server computers using integrated online libraries. Those libraries, and the clients that search them, may be distributed on a wide network.
"Z39.50 -- properly "Information Retrieval (Z39.50); Application Service Definition and Protocol Specification, ANSI/NISO Z39.50-1995" -- is a protocol which specifies data structures and interchange rules that allow a client machine (called an "origin" in the standard) to search databases on a server machine (called a "target" in the standard) and retrieve records that are identified as a result of such a search. "[from The Z39.50 Information Retrieval Standard Part1: A Strategic View of its Past, Present and Future April 1997 issue of Dlib Magazine by Clifford Lynch]
"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)]
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 provides field-level and full-text query of attributes and can conduct stateful sessions. ANSI Z39.50 is now internationally recognised as ISO 23950. See the Z39.50 Maintenance Agency.
At Eco Companion we use the Isite Information System as our Z39.50 server and search services.
URL:http://www.indexgeo.com.au/ec/about/glossary.html
Last Modified: 21 April 2001