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Re: [xml-dev] Namespace Mistake?

I'm not exactly sure of your use case so it is hard to comment, but just to be certain:
  1. Namespace is the URL, not the prefix.
  2. Prefix is a convenient shorthand for representing a certain namespace.
  3. Namespaces know nothing of versioning.
So could just as easily make your namespaces "http://apples" and "http://autocannons", bind them to a: and b: respectively then use that as a thought exercise :)

If your database queries are not intended to be scoped by version, then you might want to look at your schema versioning scheme. The "semantic versioning" concept might be a good point of reference for that activity, eg. only bump up the version number in the namespace URL if your schema update makes incompatible changes with the previous version of the schema.

In the case of incompatible schema updates, you might then want to make a conscious decision to either upgrade the entire database to the new schema or instead update all your query code to handle the new schema version (this second option is what you question in your email below). The easy (and slighty scary) option would be to just ignore namespaces. Hard to recommend an approach without knowing more about the data and application.

It does occur to me however that if both the 2.4.1 and 2.4.2 schemas are compatible with each other then it doesn't seem like a great idea to use a different namespace for each version as that will complicate the query code and any other downstream consumers of the XML.

Just my 2c anyway, hope that helps?

Gareth Oakes
Chief Architect, GPSL

From: "Timothy W. Cook" <tim@mlhim.org>
Date: Thursday, 10 October 2013 8:34 PM
To: "xml-dev@lists.xml.org" <xml-dev@lists.xml.org>
Subject: [xml-dev] Namespace Mistake?

Hi All,

I don't recall my specific reasons now but I have been reusing a namespace prefix in schemas and instance data 'mlhim2' to reference different versions of a schema reference model. 

For example:
xmlns:mlhim2="http://www.mlhim.org/xmlns/mlhim2/2_4_1"  in one version of the schema and instance data and then  xmlns:mlhim2="http://www.mlhim.org/xmlns/mlhim2/2_4_2" in another version of the schema and instance data. 

Now I think this is a mistake when I need to have multiple versions of instance data in a single database and run queries across them.  

Should I change to start using:
xmlns:mlhim241="http://www.mlhim.org/xmlns/mlhim2/2_4_1" and xmlns:mlhim242="http://www.mlhim.org/xmlns/mlhim2/2_4_2"
to be more explicit and avoid any problems?

Thanks In Advance,

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