Re: [xml-dev] Is CVS A Practical Means to Manage XML Versions In AProduc

[cbullard@hiwaay.net]

"whereas XML documents usually don't have unique IDs."

I must be confused.  Unique id/idref management is one of the problems  
to be solved although I wasn't looking at a version control system to  
do that.

It is one of the tricky bits of using XSL (say and XSL-FO) because of  
autogenerating numbers (say work package numbers) from id/idrefs where  
the person redlining the document for changes (manually) refers to WP  
numbers but the actual relationship is denoted by id/idref values that  
are NOT the same numbers.  It's one of the challenges of using the  
DTD/Schema as the governing authority yet the XSL determines the  
actual end product.  This is a different topic and not discussed often  
enough when training people to use these technologies.

There is a separate problem for procurement but I won't take that up  
at this time.  Safe to say, far too many CDRLs are pointing into black  
holes.

len





Quoting "Johannes.Lichtenberger" <Johannes.Lichtenberger@uni-konstanz.de>:

> On 09/17/2011 03:02 PM, David Lee wrote:
>> What it *doesn't* do is 'intelligent' diffs and versioning.    A classic
>> case is someone may simply load a xml file into and editor and save it,
>> without changing any 'xml stuff' but whitespace may change and cause the
>> file to be versioned and presumed 'different'.   Does that matter ? It
>> depends on your needs.
>
> Yes, it all depends. I think the OP might not be interested in
> tree-aware or XML-aware diffs and integrated query mechanisms. That is
> also ACID properties which are usually guaranteed through transactions
> in database systems -- or CAP in NoSQL systems. But yeah, I'm more
> interested in the database/storage part and maybe a bit biased ;-)
>
>> For our needs it doesn't matter at all.  We just needed document management
>> at a document level and as long as the files are not corrupted and we can
>> assign unique versions and label and pull them, it works great.     Now if
>> you want to question say 'what XML element changed and by what'  then a text
>> based version control won't answer that, but you can use other (non version
>> control) XML diff tools, pull the 2 versions and diff them.   Also if you
>> want the system to  not create a new version unless the document has
>> semantically changed it won't do that.
>
> Hm, you also have to remember that such diff tools really compute diffs
> and can't be used for change detection (for instance they may try to
> generate minimal edit scripts, but an optimal tree-to-tree correction
> algorithm is known to have a CPU runtime complexity of O(n^3) and it may
> still not be what a user really has changed, that is most of the tools
> use some kind of heuristics to speed up the diff-computation but may in
> certain cases fail horribly, for example data-oriented XML is almost
> always a problem). If you want to determine the changes a user really
> has done you must have unique node IDs, whereas XML documents usually
> don't have unique IDs.
>
> ID-based algorithms are usually also much quicker.
>
> Furthermore even XML diff tools aren't sufficient if the user wants to
> have an overview about the changes, but all of that may not be what the
> OP wants anyway ;-)
>
> But as a side note -- with time aware XPath or even XQuery-extensions a
> versioned XML-DBS can be used to analyse time-dependent data, which
> might be significant in many areas. What do others think?
>
> best regards,
> Johannes
>
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