Re: [xml-dev] Feasibility of "do all application coding in the XML langu

[Robert Koberg <rob@koberg.com>]

On Dec 2, 2008, at 9:44 AM, James Fuller wrote:

> On Tue, Dec 2, 2008 at 2:53 PM, Robert Koberg <rob@koberg.com> wrote:
>>
>> On Dec 2, 2008, at 8:20 AM, Christoph LANGE wrote:
>>
>>> On Tuesday 02 December 2008 12:52:15 James Fuller wrote:
>>>>
>>>> u might want to take another look at xquery  ... I have found that
>>>> most of the functional idioms are doable with extensions (1st class
>>>> funcs) and XQuery lends itself readily to working with XML... u may
>>>> even find you can port your code through time by directly using  
>>>> your
>>>> existing xslt transforms from within XQuery as you figure out
>>>> refactoring them.
>>>
>>> Thanks, sounds interesting!  Now that I only have basic knowledge  
>>> about
>>> XQuery, could you tell me
>>>
>>> * how to use XSL transformations from within XQuery
>>
>> very clumsily if you are using an XML DB, losing the advantage that  
>> you gain
>> by the XML DB
>
> w/o functional idioms then yes I agree, but once funcs are first class
> then all that awkwardness goes away.
>
> please expand ?

In an XML DB, XQuery can operate natively on the whole database  
without creating some DOM structure in memory. When you use XSL with  
an XML DB, you have to create some source DOM in memory to feed the  
transform. (There is some work being done in eXist to allow XSL to run  
natively on it - don't have the link...)

>
>
>>> * where to find such functional extensions
>>> ?
>>
>> You *get* to make/maintain different XQuery templates for each  
>> processor you
>> want to try out/use.
>
>
> I agree that we need the equiv of EXSLT for XQuery quick ...
> functional sigs are all different everywhere and all this is just
> vendor lockin in a new disguise.

Yep, even the same functions - eval for example - require you to  
basically maintain a different (set of) XQuery for each processor.  
There is no way to test if there is a 'function-available' or the like.

>
>
>> XQuery - the thinking man's PHP (but without PHP's standardization)
>
> hehe, I never knew that php had standardisation (I assume u being
> ironic??) and dont get me started on the probs associated with php
> (all funcs in the same namespace is a start ...)
>
> ... as for xquery it was never intended to be used as a replacement
> for php ... its an answer to sql

yea, but a lot of people are using it like PHP rather than a  
replacement for SQL on XML. It is the way XML DB vendors recommend you  
make webapps. Writers/editors (at least the ones I have been reading)  
seem to think this is the way to go. It seems like a step backwards.

best,
-Rob

>
>
> The relational data model is based on set theory and predicate logic.
> Data is represented as n-ary relations and the use of relational
> algebra is applicable. XQuery addresses the need of the xml data
> model.
>
> that being said XQuery is a useful language in its own right, just as
> much as XSLT is.
>
> Jim Fuller
>> -Rob
>>
>>>
>>>
>>> Then, I'm not so sure whether XQuery is the right solution for my  
>>> problem,
>>> as
>>> the processing order in which I do most of my XML->RDF extraction  
>>> is a
>>> depth-first recursive traversal of the input tree, i.e. what XSLT  
>>> gives me
>>> for
>>> free.
>>>
>>> Thanks in advance,
>>>
>>> Christoph
>>>
>>> --
>>> Christoph Lange, Jacobs Univ. Bremen, http://kwarc.info/clange,  
>>> Skype
>>> duke4701
>>>
>>
>>
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