this is an interesting idea?
Mon, 17 Jul 2006, Philippe Poulard wrote:
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")
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 :
""
or
"tag:dgresh@"
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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