228
Accessing Geoenvironmental Data: From On-line to Expert Systems
This is not to say that WWW is not committed to serving on into the future, but
there is not an effort to put information into a consistent format that makes it
easier to assure that a search will come up with consistent, comprehensive results.
The software is also offered freely to everyone and therefore should not be
expected to have a high level of support for fixing errors.
3 THE INTERNATIONAL DIRECTORY NETWORK
There are many non-commercial services as well which offer the capability of
searching information which has been placed in a defined format. In the Earth and
space sciences the International Directory Network (IDN) was set up specifically
for this purpose. Through the cooperation of member agencies of the
international Committee on Earth Observation Satellites (CEOS) a number of
computer network sites were established which contained directory software
designed to provide information for the community about available Earth and
space science data sets. The sites gather information in their area about available
data sets and write descriptions about the data sets in a standard format called the
Directory Interchange Format (DIF) [2]. Anyone interested in advertising the
availability of a data set can submit a description of their data in this format to an
IDN site. A Directory Interchange Format Manual can be obtained from the
author.
The sites have all agreed to exchange this information on a periodic basis. Specific
sites do this through the computer networks using automated exchange programs.
Three sites, the American coordinating node (the Global Change Master
Directory) at Goddard Space Flight Center in Greenbelt, Maryland, the Asian
coordinating node in Hatoyama, Japan, and the European coordinating node in
Frascati, Italy have agreed to collect all DIF information in their databases and
make it freely available to users accessing their directories through networks or
dial-in lines. Other sites are more specialized, such as the NASA Master Directory,
also at Goddard Space Flight Center which emphasizes NASA-funded data
information with special emphasis on the space sciences. Information about
accessing or contacting most of the nodes has been compiled in a brochure
entitled "The International Directory Network" [3] which is available from the
author.
4
INTEROPERABILITY
The unifying factor of the Directory Interchange Format provides a common
"look and feel" to the information available through the IDN. On the World-Wide
Web, standard interfaces such as the Mosaic interface provide this common "look
and feel" as well. The commonality makes it easier for the user to access differing
information systems yet know how to operate in each. The ability to use different
information systems in a similar way is a measure of the interoperability of these
systems. Finding or displaying information in a common way is only half the
battle, however. Users must also be able to quickly acquire, understand, and use the
data. To make these types of services "interoperable" so that users can quickly
understand and use the services is a more difficult task.
Accessing Geoenvironmental Data: From On-line to Expert Systems
This is not to say that WWW is not committed to serving on into the future, but
there is not an effort to put information into a consistent format that makes it
easier to assure that a search will come up with consistent, comprehensive results.
The software is also offered freely to everyone and therefore should not be
expected to have a high level of support for fixing errors.
3 THE INTERNATIONAL DIRECTORY NETWORK
There are many non-commercial services as well which offer the capability of
searching information which has been placed in a defined format. In the Earth and
space sciences the International Directory Network (IDN) was set up specifically
for this purpose. Through the cooperation of member agencies of the
international Committee on Earth Observation Satellites (CEOS) a number of
computer network sites were established which contained directory software
designed to provide information for the community about available Earth and
space science data sets. The sites gather information in their area about available
data sets and write descriptions about the data sets in a standard format called the
Directory Interchange Format (DIF) [2]. Anyone interested in advertising the
availability of a data set can submit a description of their data in this format to an
IDN site. A Directory Interchange Format Manual can be obtained from the
author.
The sites have all agreed to exchange this information on a periodic basis. Specific
sites do this through the computer networks using automated exchange programs.
Three sites, the American coordinating node (the Global Change Master
Directory) at Goddard Space Flight Center in Greenbelt, Maryland, the Asian
coordinating node in Hatoyama, Japan, and the European coordinating node in
Frascati, Italy have agreed to collect all DIF information in their databases and
make it freely available to users accessing their directories through networks or
dial-in lines. Other sites are more specialized, such as the NASA Master Directory,
also at Goddard Space Flight Center which emphasizes NASA-funded data
information with special emphasis on the space sciences. Information about
accessing or contacting most of the nodes has been compiled in a brochure
entitled "The International Directory Network" [3] which is available from the
author.
4
INTEROPERABILITY
The unifying factor of the Directory Interchange Format provides a common
"look and feel" to the information available through the IDN. On the World-Wide
Web, standard interfaces such as the Mosaic interface provide this common "look
and feel" as well. The commonality makes it easier for the user to access differing
information systems yet know how to operate in each. The ability to use different
information systems in a similar way is a measure of the interoperability of these
systems. Finding or displaying information in a common way is only half the
battle, however. Users must also be able to quickly acquire, understand, and use the
data. To make these types of services "interoperable" so that users can quickly
understand and use the services is a more difficult task.