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even if the resource has been moved to a different server. Using URNs as persistent identi-
fiers would ensure that when a document is moved or its ownership changes, the links to it
would remain active.
Yet, a persistent identifier system only works, if it is regularly maintained. If the location
of a web resources changes, the URN must be linked to this new location.Therefore, for
the system to be functional, a resolver database is needed. A resolver database automatically
maps, through server software, the unique resource name to its current location.The use of
Uniform Resource Names is still at an experimental stage and as current prototypes to
manage and track URNs are not functioning well, persistent identifier systems have not yet
reached a critical mass.
Naming on the web and the concept of Uniform Resource Identifiers (URIs) still are
hot areas that need considerable research.The objective would be to realise URI-
management systems that allow to track, monitor and manage persistent access to digital
uniquely identified information resources on the web. Such a system would support the
following properties of naming:
Scope: names would be globally valid and location transparent,
uniqueness: names would be globally unique and valid for the whole life-time of a
resource,
readability: usually well supported by current web URLs (except for e.g. cgi-based
location),
scalability: aspect of number of accesses, number of resources managed,
mobility: re-location of resources, names should be location independent,
querying: users might only know some properties of a resource but not the name.
Besides the Uniform Resource Name URN and the Uniform Resource Locator URL,
a persistent identifier system based on the URI concept also provides the Uniform
Resource Characteristics URC as general category to further describe the information
object.This category might include a reference to the terms of use and its cost.
224
IX TECHNOLOGY
Persistent identifier system
Uniform Resource Identifier System
LOCATION
Meta data descriptions
Location-independent names
in use
experimental
explor
ed,but no
critical mass
Southhampton Public Library, 2nd floor, 3rd
aisle, 2nd shelf, 3rd book from the left
http://ftp.somewhere.com
ISBN 3-920993-23-7
urn:duns:002373846: annual report
urn:fpi:-//Sun%20 Microsystems::SunSoft//
DOC%20Solaris%20Manual//EN
urn:uuid:BH39746-74H64-74H64-74HGU/
intellectual property rights, user
profiles, etc. i.e.
genre:book; title;Hypermedia and
the We; author: D.Lowe, W, Hall
URL
Uniform
Resource
Locator
URI
Uniform
Resource
Identifier
URN
Uniform
Resource
Name
URC
Uniform
Resource
Characteristics
Source: Salzburg Research, 2001