Jump to content

help understanding namespace


XSLTnewbie

Recommended Posts

I see this kind of declaration a lot in XSL files:

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">

and I tried opening the address referred to in the above declaration (http://www.w3.org/1999/XSL/Transform), and it's just a regular webpage, not some kind of collection of commands or syntax like I expected. my questions are:

1. how is this possible? how does machine understand commands like xsl:value-of if there's no specific codes in that URL?

2. what would happen if w3.org is down? will all web service that uses this namespace blow up?

 

and in the web service XML message, the structure is like so:

<foo:concat xmlns:foo="http://ttdev.com/ss"><s1>abc</s1><s2>123</s2></foo:concat>

let's say ttdev.com is a domain name I purchased (I put my web service in that server). and let's say for some reason, I change the domain name to myservice.com (switch to cheaper provider, etc.), does this mean the above message will blow up when trying to access my service which is now located at myservice.com? thanks a lot

Link to comment
Share on other sites

I also have trouble understanding the difference between qualified and prefixed elements:

<schema xmlns=”http://www.w3.org/2001/XMLSchema”targetNamespace=”http://www.example.com/name”xmlns:target=”http://www.example.com/name”>

and this one:

<xs:schema xmlns:xs=”http://www.w3.org/2001/XMLSchema”targetNamespace=”http://www.example.com/name”xmlns=”http://www.example.com/name”>

what's the difference? I only see that schema is prefixed, but name is not in the latter. what are the effects if I choose one over the other?

 

also this:

<name xmlns=”http://www.example.com/name”><first>John</first><middle>Fitzgerald</middle><last>Doe</last></name>

the example said that the elements (first, middle and last is qualified). I'll just assume that that would mean they won't get mixed up with other <first> element that belongs to other vocab.and also, is this what you call default namespace?

<n:name xmlns:n=”http://www.example.com/name”><n:first>John</n:first><n:middle>Fitzgerald</n:middle><n:last>Doe</n:last></n:name>

now this one is a bit weird. why do you need to prefix all the elements when previous example already qualifies the elements that belong to "name" vocab?

thanks

Link to comment
Share on other sites

 

 

what's the difference? I only see that schema is prefixed, but name is not in the latter. what are the effects if I choose one over the other?

The second one creates the xs namespace, the first one doesn't have a namespace prefix.

 

 

 

I'll just assume that that would mean they won't get mixed up with other <first> element that belongs to other vocab

They won't get mixed up as long as there aren't multiple vocabs in the same file. If there are, then you need to use namespaces to separate them, that's really what namespaces are for. Namespaces are a concept in languages other than XML, they are used to separate different pieces of code that might share names. They avoid naming conflicts when everything is in the same namespace.

 

Those examples are just illustrating the concepts, but they aren't all that useful on their own. With the last example, you wouldn't need to use a namespace if that was the only thing in the file.

Link to comment
Share on other sites

  • 5 weeks later...

If you have a single XML file that uses multiple namespaces, and every namespace has a "name" element, then you need to prefix every name element with the namespace that it belongs to. Otherwise it wouldn't know which name element you're referring to, it could be the name element from any of the namespaces. You specify the namespace to remove ambiguity.

Link to comment
Share on other sites

sorry, you lost me there. are we still talking about the <first> and <middle> and <last> element here? I was confused whether to add prefix to <first>, <middle> and <last> if it's contained in a prefixed element <name> like shown below:

<n:name xmlns:n=”http://www.example.com/name”><first>John</first><middle>Fitzgerald</middle><last>Doe</last></n:name>

and if I do, what's would the effect be if I dont add prefixes to <first>, <middle> and <last> element?

Thank you so much.

Link to comment
Share on other sites

From what I understand, you only need to prefix elements with a namespace if they are going to conflict with other elements from other namespaces. If you're dealing with a single XML element with a single namespace like you're showing then I don't think you need the prefix at all.

Link to comment
Share on other sites

<hn:husbandname xmlns:hn=”http://www.example.com/name”><first>John</first><middle>Fitzgerald</middle><last>Doe</last></hn:name><wn:wifename xmlns:wn=”http://www.example.com/name”><first>Jane</first><middle>Fitzgerald</middle><last>Doe</last></wn:name>

how about this one then? do I need to prefix the <first>, <middle> and <last> elements? and if I do, whose elements should I prefix? the husband, the wife or both, or neither?

thanks

Link to comment
Share on other sites

in what case would asking for a first name be returning all the first names? I'm only familar with xslt, so even without the namespace for husbandname and wifename element, I'll be able to access using "/husbandname/first" XPath expression. Am I missing something here? thanks

Link to comment
Share on other sites

  • 6 years later...

Does the namespace text HAVE to take the form of a url?

Since a namespace is just intended as a text identifier should another section of XML be used in the same webpage (such as different XML markup languages or those being called from different scripts) can another form for the namespace text be used, such as an email address or something else that should be unique? If all the sources are from a single website, they can be tracked and a unique identifier name assigned to them like "identifier1" and "identifier2" .

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...