Topic 1: What do we mean by "GUID"?

Patricia Mergen p_mergen at YAHOO.COM
Thu Oct 13 05:51:17 CEST 2005

--- Kevin Richards <RichardsK at LANDCARERESEARCH.CO.NZ>

> From my computer-oriented viewpoint I consider a
> GUID in our discussion domain to be a an identifier
> (a character string that represents an object) that
> "points" to a particular record in a database or
> file on a computer.  The idea is that the ID is
> globally unique - ie there is no other identifier in
> the world that is the same, but this is not easy to
> guarantee.  I think the main aim here is to ensure
> it is unique within the domain for which it was
> intended (and a the main reason for using an
> existing GUID system such as ARK).
> I thnik my main point here is that the GUID must
> represent a digital object (eg database record) and
> cannot represent a physical object (ie you cannot
> transfer the physical object via the Internet).  A
> record in a database may refer to a physical object,
> however the GUID will refer to the database record
> and the physical object will be "described" in the
> database record and referred to perhaps by a
> physical address/location.

I tend to agree with this suggestion that the GUIDS
should apply to the records served through the
GBIF/TDWG network. The physical objects like for
example the specimens in the institution have already
their identifiers which are not GUIDS and serve for
internal use mainly. Currently these identifiers are
already used in DarwinCore or ABCD data served to GBIF
to link  to Physical objects or additional information
available elsewhere.

> GUIDs should be assigned to any record/file/etc that
> will be served up to external users.

Could GBIF/TDWG in this context not play the role of a
ticketting service serving "GUIDS" for the UNIT level
data to the providers?

For example if a provider wants to provide 2000 new
records to GBIF, 2000 unique identifiers (like
accession numbers) will be assigned to his 2000

The interlinking and localisation business could than
be dealt with at an other level using the
"description"  of the record.


> I think the ARK article does cover most of the
> issues surrounding GUIDs, except implementation
> specific issues such as who the authorities should
> be and what form/granularity the data to be served
> up should be in.  I still favour LSIDs where the
> resolution of an LSID works in well with the DNS
> system, and perhaps because they are actuially
> intended for the life sciences domain.  The "problem
> definition" of the GUID as described below in
> Donald's email seems to sum up the requirements of a
> GUID to me.  I'm not sure that "statements of
> commitment" are a job for the GUID itself, but they
> should be implied.  Implied commitments for LSIDs
> include byte-identical data every time and infinite
> persistence of the data (a big ask I know).
> Kevin
> >>> dhobern at GBIF.ORG 12/10/2005 3:37 a.m. >>>
> [ I will be trying to provide some structure to
> discussions in this mailing list by raising specific
> topics and looking for comments.  Please keep the
> Topic number in responses ] Topic 1: What do we mean
> by GUID? The most fundamental thing that we need to
> establish as we consider a GUID implementation is a
> definition for "GUID" in this context.  We have been
> using a number of terms to describe the identifiers
> we need (unique, resolvable, persistent, etc.).
> I've been spending some time following up on Rod
> Page's recommendation that we consider the use of
> Archival Resource Keys (ARK) from the California
> Digital Library (see
> The CDL web site includes an excellent overview of
> this GUID model, which also serves as an excellent
> introduction to the issues involved.  I would urge
> you all to read this document * it's only nine pages
> long!):
> This document arrives at the following problem
> definition for persistent, actionable identifiers:
> The goal: long-term actionable identifiers.
> Requirement: that identifiers deliver you to objects
> (where feasible). Requirement: that identifiers
> deliver you to object metadata. Desirable: each
> object should wear its own identifier. Requirement:
> that identifiers deliver you to statements of
> commitment. The problem: URLs break for some objects
> (that is, associations between URLs and objects are
> not maintained), and we have no way to tell which
> ones will or won't break. Why URLs break: because
> objects are moved, removed, and replaced *
> completely normal activities * and the provider in
> each case demonstrates insufficient commitment to
> update indirection tables, or to plan identifier
> assignment carefully. Persistence is in the mission
> of few organizations. Conventional hypothesis: use
> indirect names (PURLs, URNs, Handles) instead of
> URLs; what worked for DNS should work for digital
> object references.  Wrong. Indirection is
> spectacularly successful and elegant in DNS, but
> it's a side issue in the provision of digital object
> persistence.  This document clearly identifies
> issues around provider service commitments as the
> key problem that needs solving.  The construction of
> ARKs seeks to address this in a couple of ways.  It
> separates the role of Name Assigning Authority (i.e.
> who initially assigns the identifier) from that of
> the Name Mapping Authority (i.e. who is able to map
> the identifier to the data object at any particular
> time).  It also defines a simple standard
> relationship between three things: the data object,
> the metadata for the object, and a commitment
> statement from the provider as to what aspects of
> persistence are guaranteed. ARK is a technology that
> we have not really considered up to this point.  My
> question for discussion is what, if anything, is
> missing or wrong about the problem definition
> provided in this document?  If we agree that it
> provides a crisp definition of what we need, that in
> itself will be a major step forward. Please provide
> your thoughts. Donald
> Donald Hobern (dhobern at
> Programme Officer for Data Access and Database
> Interoperability
> Global Biodiversity Information Facility Secretariat
> Universitetsparken 15, DK-2100 Copenhagen, Denmark
> Tel: +45-35321483   Mobile: +45-28751483   Fax:
> +45-35321480
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