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RE: [xml-dev] Basic namespace question
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You should focus first on understanding my answer.: ) Clarification: I
was actually replying only to the single question of if a resolvable URI is
used, is information from that URI being used in the document somehow. I did
understand Philippe Poulard's response, and was responding to a question from
the original poster that no one had responded to yet.
Joe
Joseph Chiusano
Associate
Booz Allen Hamilton
700 13th St. NW, Suite
1100
Washington, DC 20005
O: 202-508-6514
C: 202-251-0731
Visit us online@ http://www.boozallen.com
Hi,
Chiusano Joseph said => Although it could/should be (if it is indeed a resolvable URI), that is not a requirement
I think it's a good idear too, like giving related documentation and schema and so forth if you choose a "resolvable URI"(Thx for the terms, I didn't knew it(my english is so poor ..:)), but keep in mind that's a lucky side effect for people that understand namespaces, and in the other side, the greater source of confusion for the rest of the world.
You should focus first on undersanding Philippe Poulard's answer, and
after try to use this side effect of choosing a "resolvable URI" (thx
again :).
Regards,
Xavier
Chiusano Joseph a écrit :
Also, to answer the following:
Is information from that URI being used in the XML document somehow?
Although it could/should be (if it is indeed a resolvable URI), that is not a requirement. For example, if you use a URI of 'http://ecommerce.org/schema' per your example below, chances are that the information in the XML document somehow relates to e-commerce (it would be a good, logical bet). This not have to be the case, but it seems like good practice to me to have such an association. If your URI were more specific, perhaps to indicate a certain domain (such as "automotive"), then chances are that the information in the XML document somehow relates to automotive e-commerce, perhaps the purchase of auto parts.
Joe
Joseph Chiusano
Associate
Booz Allen Hamilton
700 13th St. NW, Suite 1100
Washington, DC 20005
O: 202-508-6514
C: 202-251-0731
Visit us online@ http://www.boozallen.com
-----Original Message-----
From: Philippe Poulard [mailto:Philippe.Poulard@sophia.inria.fr]
Sent: Monday, July 17, 2006 12:22 PM
To: Daniel Gresh
Cc: xml-dev@lists.xml.org
Subject: Re: [xml-dev] Basic namespace question
hi,
namespace URIs are used to disambiguish names used in elements (and sometimes in attributes) ; the idea is to consider that a name has 2 parts, an ID and a local name ; 2 elements that have the same local name are distinct when the ID you choose is not the same than mine ; now what would happenned if unfortunately we have both choosen the same ID ? we would have a clash ; the solution would be :
1) to disambiguish again our elements by considering that a name has 3 parts (an ID, another ID and a local name) ; now loop again if we choose again the same IDs
2) to choose a better ID
so we must ensure that when you choose an ID, it is not the same than mine ; the idea is to use a "universal ID", an ID that is unique all over the world
candidates :
-URIs ("http://foo.com/myNs" or "urn:isbn:9-780201-770049") -GUIDs (they are also expressible with URN : "urn:guid:etc...") -à la Java ("com.foo.myNs") -...
URIs win
avoid using "that text document" : even if XML processors won't complain because it's not an URI string, it is not a unique string
so, the kind of URI you could use could be something like this :
"http://lle.rochester.edu/myProject/myNs"
or
"tag:dgresh@lle.rochester.edu:2006-07-17:myNs"
or any other, as long as it is unique
Daniel Gresh wrote:
I have a basic question about XML Namespaces, as I just cannot seem to
fully grasp the concept.
I know how to set up a namespace, and I know how they are used in the
document and such; my question is mainly about the URI associated with
a namespace. Let's use this as an example:
|<x xmlns:edi='http://ecommerce.org/schema'>
<!-- the 'price' element's namespace is http://ecommerce.org/schema
--> <edi:price units='Euro'>32.18</edi:price> </x>||
Now I'm not too sure how to phrase this question, but here goes: do I
have to associate a URI with a namespace? In the above example, what
would be the case if there was no xmlns declaration and the ns "edi"
was used? I suppose what I am asking is: what is the benefit of
declaring an xmlns in the manner xmlns:prefix='URI'? Is information
from that URI being used in the XML document somehow? It's all very confusing to me.
Also, let's say I have a simple text document located somewhere on my
hard drive, like C:\document.txt. If I wanted to define a namespace
for that document, such as xmlns:doc='that text document', how
exactly would I do so? Is it even needed?
Thanks in advance,
Dan
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--
Cordialement,
///
(. .)
--------ooO--(_)--Ooo--------
| Philippe Poulard |
-----------------------------
http://reflex.gforge.inria.fr/
Have the RefleX !
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