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RE: Venetian Blinds vs Garden of Eden patterns forindustry sta

• From: Philip Fennell <Philip.Fennell@marklogic.com>
• To: Pete Cordell <petexmldev@codalogic.com>, "xml-dev@l..."<xml-dev@l...>
• Date: Thu, 28 Oct 2010 04:59:54 -0700

Pete wrote:

> That way you only ever have one namespace declaration (ignoring QName 
> issues) irrespective of the types you use from other namespaces, and you 
> only have the root element as qualified.  So your XML instance looks like:
> <myNS:root xmlns:myNS="abc">
>     <element1>
>         <elementWithTypeDefinedInAnotherNamespace>
>         </elementWithTypeDefinedInAnotherNamespace>
>     </element1>
> </myNS>
> The instance is appropriately tagged with it's namespace, but it's all 
> clearly done in one place and there's no other namespace gotchas to worry 
> about.

I think I see what your trying to do but surely with the above approach you are going to have problems when processing fragments of the document because you'll lose the context if the fragments are taken as-is. I presume, to counter that you're talking about having the 'context' or 'root' wrapper being used to contain any fragment of the document which means that the container element's content model must allow all possible elements, from the schema, as children (or may be a defined sub-set of all). In more complex compound documents (XHTML + XForms or XSLT + XHTML + XForms) that'd introduce a lot of noise into the document and add a different kind of complexity where you're switching namespaces more frequently as you traverse the tree in and out of context wrappers. From a readability point of view you'd be constantly having to scan back up the tree to get you namespace context. Within an XSLT transform that'd be a nightmare.

Regards

Philip Fennell 
Consultant
MarkLogic Corporation
Mobile +44 (0) 7824 830 866
email  Philip.Fennell@marklogic.com
web    www.marklogic.com

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________________________________________
From: Pete Cordell [petexmldev@codalogic.com]
Sent: 28 October 2010 11:16
To: xml-dev@lists.xml.org
Subject: Re:  Venetian Blinds vs Garden of Eden patterns for industry standards XML Schemas

One thing I'm surprised is not more popular is to always use Venetian Blind,
even across namespaces, BUT make local elements unqualified, i.e. use
elementFormDefault="unqualified".

That way you only ever have one namespace declaration (ignoring QName
issues) irrespective of the types you use from other namespaces, and you
only have the root element as qualified.  So your XML instance looks like:

<myNS:root xmlns:myNS="abc">
    <element1>
        <elementWithTypeDefinedInAnotherNamespace>
        </elementWithTypeDefinedInAnotherNamespace>
    </element1>
</myNS>

The instance is appropriately tagged with it's namespace, but it's all
clearly done in one place and there's no other namespace gotchas to worry
about.

The approach mirrors JSON's response to "there's nothing like XML namespaces
in JSON."

I think the issue is that the interpretation of a element depends on the
context provided by the parent and XSLT and other XPath technologies have
difficulty with that.

Spot the outsider!

Pete Cordell
Codalogic Ltd
Interface XML to C++ the easy way using C++ XML
data binding to convert XSD schemas to C++ classes.
Visit http://codalogic.com/lmx/ or http://www.xml2cpp.com
for more info
----- Original Message -----
From: "Pete Cordell" <petexmldev@codalogic.com>
To: <xml-dev@lists.xml.org>
Sent: Thursday, October 28, 2010 10:58 AM
Subject: Re:  Venetian Blinds vs Garden of Eden patterns for
industry standards XML Schemas


> FWIW I would use:
>
> <xs:element name="" type=""/>
>
> (i.e. Venetian Blind) where type is within the same namespace/schema as
> the element, and:
>
> <xs:element ref=""/>
>
> (i.e. Salami Slice) when the element(/type) being accessed is in a
> different namespace.
>
> To give it a name I'll call it Venetian Slice!
>
> By analogy to a class interface, I see the global elements as the public
> members of an interface, and the global types as the private members.  The
> interface should only publically expose what it has to, and Venetian Blind
> provides a non-narrative way to express that.  Accessing a new namespace
> is analogous to accessing a new class, and so the public interface (i.e.
> global elements) of that namespace have to be used.
>
> That should open up the discussion!
>
> Pete Cordell
> Codalogic Ltd
> Interface XML to C++ the easy way using C++ XML
> data binding to convert XSD schemas to C++ classes.
> Visit http://codalogic.com/lmx/ or http://www.xml2cpp.com
> for more info
> ----- Original Message -----
> From: "Dennis Sosnoski" <dms@sosnoski.com>
> To: <xml-dev@lists.xml.org>
> Sent: Thursday, October 28, 2010 6:41 AM
> Subject: Re:  Venetian Blinds vs Garden of Eden patterns for
> industry standards XML Schemas
>
>
>>
>> If you're thinking of using data binding for working with the data in
>> applications I'd strongly recommend a Venetian Blinds approach. Most
>> data binding approaches turn Garden of Eden into an amorphous foam of
>> tiny classes - which is, after all, exactly what Garden of Eden
>> represents in XML terms.
>>
>> Associating the name "Garden of Eden" with this concept of pureed
>> structure was excellent marketing, but doesn't really give the right
>> impression. I'd suggest "Element Soup" as an alternative. :-)
>>
>>  - Dennis
>>
>>
>> On 10/28/2010 05:31 AM, Lech Rzedzicki wrote:
>>> Hi all.
>>>
>>> I am now involved in developing the next iteration of schemas to
>>> standardise information storage and exchange for trademarks and design
>>> (there is also some cooperation with patent people).
>>> The current standards (TM-XML and DS-XML) use a venetian blind pattern
>>> because it nicely mimics OO model, so it's easy to generate classes
>>> and objects, also it hides element definitions so there's no conflicts
>>> when processing them. Finally the naming convention (not my idea)
>>> means that the element names are not reusable anyway.
>>> Some people are now proposing that we move to "Garden of Eden" design
>>> patter, but I don't see that as a particularly smart move in the
>>> context of our domain.
>>> I have noticed that many of the schemas in the industry, for instance
>>> UBL have gone for Garden of Eden first and and later reverted to
>>> Venetian Blinds.
>>> I am very interested in some thoughts from the trenches as to why one
>>> or the other approach might be more useful in a committee driven
>>> standards with contributors from different domains.
>>>
>>> No need to point me to google either - I have read all the articles
>>> about it [1,2,3] and authored schemas that are in production now both
>>> ways, but still unconvinced either way...
>>>
>>>
>>> References:
>>>
>>> [1] A slideshows on various approaches:
>>> http://dret.net/lectures/xml-fall08/xsd-2#(11)
>>> [2] http://www.xfront.com/GlobalVersusLocal.html - schema best practices
>>> [3] http://www.ibm.com/developerworks/xml/library/x-schemascope/
>>> etc...
>>>
>>> _______________________________________________________________________
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>>>
>>
>> _______________________________________________________________________
>>
>> XML-DEV is a publicly archived, unmoderated list hosted by OASIS
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>>
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>>
>




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• Follow-Ups:
  • Re: Venetian Blinds vs Garden of Eden patterns for industry standards XML Schemas
    • From: "Pete Cordell" <petexmldev@codalogic.com>
  • Re: Venetian Blinds vs Garden of Eden patterns for industrystandards XML Schemas
    • From: David <dlee@calldei.com>

• References:
  • Re: Venetian Blinds vs Garden of Eden patterns for industry standards XML Schemas
    • From: "Pete Cordell" <petexmldev@codalogic.com>