Re: [xml-dev] Namespace Mistake?

[Fraser Goffin <goffinf@gmail.com>]

> I don't believe you can assign two different namespaces the same prefix.

You can if they are in different scopes.

Fraser.

On 10/10/2013, Bob Jolliffe <bobjolliffe@gmail.com> wrote:
> Hi Tim
>
> I've no idea if this is best practice, but what I have done in the past
> when I have minor (backward-compatible) modifications to a schema is keep
> the namespace the same but also have a minorVersion attribute to allow
> consumers to recognize the version, and keep namespace change for more
> breaking changes.
>
> I don't believe you can assign two different namespaces the same prefix.
>
> Bob
>
>
> On 10 October 2013 21:00, Timothy W. Cook <tim@mlhim.org> wrote:
>
>> Thanks for the prompt reply Gareth.
>>
>> Well, the schemas are not 100% compatible, that is why I version them.
>>  The use case is such that we do not want to convert the data from one
>> version to another. It is for longitudinal healthcare records and this
>> has
>> been (and continues to be) a problem, especially when using SQL
>> databases.
>>  The science changes over time but what was recorded at that point in
>> time
>> is what is important; forever. Including the semantic links that are
>> embedded in RDF annotations in the schema.
>>
>> I understand that the URI is the namespace but when I use the same prefix
>> to represent different namespaces, will that cause a problem?  One other
>> thing to note is that I use UUIDs for complexType and element names so
>> any
>> combination of prefix:element-name will always be unique, even though the
>> prefix is the same.
>>
>> My question actually comes up because I am using MarkLogic and it won't
>> allow me to define mlhim2 as a QName with two different namespaces.  So,
>> maybe it is only a MarkLogic limitation because of the way the database
>> works?
>>
>> --Tim
>>
>>
>>
>> On Thu, Oct 10, 2013 at 4:49 PM, Gareth Oakes
>> <goakes@gpslsolutions.com>wrote:
>>
>>> 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
>>> www.gpslsolutions.com
>>>
>>> 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,
>>> Tim
>>>
>>>
>>>
>>> --
>>> MLHIM VIP Signup: http://goo.gl/22B0U
>>> ============================================
>>> Timothy Cook, MSc           +55 21 94711995
>>> MLHIM http://www.mlhim.org
>>> Like Us on FB: https://www.facebook.com/mlhim2
>>> Circle us on G+: http://goo.gl/44EV5
>>> Google Scholar: http://goo.gl/MMZ1o
>>> LinkedIn Profile:http://www.linkedin.com/in/timothywaynecook
>>>
>>
>>
>>
>> --
>> MLHIM VIP Signup: http://goo.gl/22B0U
>> ============================================
>> Timothy Cook, MSc           +55 21 94711995
>> MLHIM http://www.mlhim.org
>> Like Us on FB: https://www.facebook.com/mlhim2
>> Circle us on G+: http://goo.gl/44EV5
>> Google Scholar: http://goo.gl/MMZ1o
>> LinkedIn Profile:http://www.linkedin.com/in/timothywaynecook
>>
>