What is a namespace ... really?
Roger L. Costello
costello at mail11.mitre.org
Fri Jan 15 18:27:13 GMT 1999
I have been closely monitoring (with great interest!) all the discussion
arising from my question on what is a namespace. It seems that people have
differing ideas on what it is. I would like to try to summarize the points
of view, and add my own two cents.
(1) A namespace is just a URI. It references some domain. It is simply
there to tell an application/processor what domain the associated XML
elements hail from.
(2) A namespace is a URI to a DTD. It references a domain and also a DTD
within the domain. In addition to telling an application/parser what
domain the associated XML elements hail from, with this namespace
declaration a validating parser could validate that portion of your XML
document against the DTD at that URI.
So, with point-of-view (2) this is a valid namespace declaration:
and this is not a valid namespace declaration:
because there is no referenced DTD at that domain.
Is this a fair assessment of the points of view?
My two cents:
What is the purpose of namespaces? It is my understanding that the purpose
of namespaces is twofold:
(a) Disambiguation. e.g., if BookCatalogue is defined in another
DTD that you are using then namespaces allow you to distinguish
BookCatalogue in DTD A from Bookcatalogue in DTD B
(b) Reuse/validation. e.g., if you declare that BookCatalogue
comes from a DTD in some domain then conceivably a parser
could validate that portion of the XML document.
Who's right? What is "truth"? /Roger
xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev at ic.ac.uk
Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/
To (un)subscribe, mailto:majordomo at ic.ac.uk the following message;
To subscribe to the digests, mailto:majordomo at ic.ac.uk the following message;
List coordinator, Henry Rzepa (mailto:rzepa at ic.ac.uk)
More information about the Xml-dev