RE: Change tracking processing instructions and deletion

It is however commonplace in personal-productivity software that changes can be accepted and reject in any order so long as they are not collision cases (though Microsoft Word and *Office Writer may do something anyhow).  These product also allow tracking to be turned on and off for various reasons.  
 
At DChanges 2014 on 16 September, Operational Changes and pointing *into* documents was talked about a great deal.  
 
I remain nervous about it.  Any defect or missed change has the potential of completely corrupting the result.  Cases where change information is somehow anchored within the changed document has defects be more-likely local and not having such global consequences.  
 
I would much rather us an approach that is not so brittle and based on the perfect-software/-programmer assumption.  Even perfect software experiences misadventures in the face of multi-point failures, problems with saves during a shutdown, etc.  Oh, and that raises issues about document recovery too, something that most products now support in some manner and, while such incidents are certainly more rare, the user lists I follow reveal scarcity but not absence.
 
-   Dennis
 
PS: If changes are meant to preserve digitally-signed originals, some counterpart of external tracking is required (apart from prospective brute-force cases).  That came up a little bit at DChanges 2014 also.
 
From: Claudius Teodorescu [mailto:claudius.teodorescu@gmail.com] 
Sent: Wednesday, September 17, 2014 09:28
To: public-change@w3.org
Subject: Fwd: Change tracking processing instructions and deletion
 
 
---------- Forwarded message ----------
From: Claudius Teodorescu <claudius.teodorescu@gmail.com <mailto:claudius.teodorescu@gmail.com> >
Date: Wed, Sep 17, 2014 at 2:42 PM
Subject: Re: Change tracking processing instructions and deletion
To: Robin LaFontaine <robin.lafontaine@deltaxml.com <mailto:robin.lafontaine@deltaxml.com> >


Hi,
 
On Thu, Sep 4, 2014 at 5:44 PM, Robin LaFontaine <robin.lafontaine@deltaxml.com <mailto:robin.lafontaine@deltaxml.com> > wrote:
Hi Claudius,

I think one issue with XQuery Update for change tracking is that although it looks good for one transaction, it does not work well for multiple transactions because the XPaths will change as the document is changed. In theory you could undo the changes in order (though only if every change had been tracked), but it would be almost impossible to undo in any other order with predictable results.
 
You can have one transaction containing multiple update operations, like:
<?change user="nigel" time="2014-08-27 15:12:00" change="(delete node //p[1], insert node &lt;p xml:lang="en"&gt;Hello World&lt;/p&gt; into //body)" ?>.
 
But, this will not work with randomly acceptance/rejection of changes, as you said. On the other hand, dealing with random acceptances/rejections is hard for separate change logs, not matter how they are written.
Keeping the change log within the document is needed to be a positional approach, in order to allow random acceptances/rejections, as the change log records are to be nearby the former/new content.
So, this positional approach seems to be the answer for change log kept within document.
I wonder if this system has some issues with nested changes, either for undoing or for accepting/rejecting any of them.


Claudius
 

Consider also a document with a series of XQuery Update changes, it would be quite hard to work out how to display these changes, but much easier if the changes are embedded in PIs within the document (or indeed in markup).

There is a design decision about where to keep the changes:
1. Within the document
2. Separate, e.g. in a series of transactions in XQuery Update

Most current systems I believe use choice 1, either as markup (e.g. Word, ODF, Arbortext) or PIs (e.g. oXygen, XMetaL, Xopus). I think there are good reasons for this choice.

Robin

-- 
Robin La Fontaine
Director
DeltaXML Ltd "Experts in information change"
 
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