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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: RE: defining xml diff/changes in xml : XUpdate etc
 Is there no way off this list?????? --- Robin Berjon <robin.berjon@e...> wrote: > On Apr 12, 2006, at 20:47, Adrian Mouat wrote: > > The IETF had a bof on the subject of xml patching > - the notes can > > be found here: > > > > > http://www3.ietf.org/proceedings/05nov/xmlpatch.html > > > > Basically there seems to be no current support for > the creation of > > a standard. > > Have you taken a look at REX? It is not intended to > be a generic XML > patch language, but since the list of supported > events is to be made > open-ended, you could devise a set of events that > correspond to > patching operations. It may not be an ideal > solution, but it does > have strong support in terms of moving the standard > forward so piggy- > backing that might be a good idea. > > > Michael Kay wrote: > >> * must the effect of applying diffs be > independent of the order in > >> which > >> they are applied? > > > > Surely impossible?? I can't add a node to a > subtree that doesn't > > exist. Or do you have a completely different > format in mind? > > It depends on whether you have the constraint of > being able to create > a WF XML document at each step, or if your patches > can work on > intermediate in-memory representations that may not > hold the entire > tree and may have ghost nodes. IIRC in theory MPEG-B > updates can send > you fragment updates that are inside nodes that you > don't yet have > (you would use the path to create stubs). In > practice I'm not sure > it's fully supported, but I can ask. > > >> * do diff files need to be human-readable? > > > > I think not - they can be transformed into human > readable formats. > > I guess the question is also about whether they have > to be XML. I > think it's best but then I'm an integrist :) > > >> * do diff files need to be small? > > > > Is XML ever? > > Yes of course, just use an efficient XML format! Oh > wait, it's not > Friday, sorry. > > >> * what kind of changes need to be diff'ed? Do > they include, for > >> example, > >> renaming of nodes? Do they include any bulk > changes, such as > >> deleting all > >> instances of a particular attribute? Do they > include changes at > >> the lexical > >> level, e.g. changing the expansion text of an > internal entity? Do > >> they > >> include DTD changes?DUL doesn't handle > expressions like this, and > >> I don't think it should - leave that to XQuery > update. > > Entities are a hard question - there are even more > questions if you > > consider whether they should be resolved or not. > DTD changes are > > not supported in DUL. > > I would personally opt for supporting only what the > XPath DM > supports, but I realise that this limits some of the > use cases. > > The EXI WG is working on a similar issue related to > the fidelity of > efficient XML encodings, which is basically the > issue of the Infoset, > namely what "matters" in an XML document. XML itself > is defined > entirely at the syntax level, but for some problems > if you stick just > to that you end up with good old gzip (for the > efficient XML case) or > good old diff (for the diff case). Presumably there > are use cases > that require more than what those options can bring > to the table, > which is where things get interesting. Currently I'm > working on a > scale measuring fidelity along the following lines. > It is meant to > evaluate efficient XML formats, but I think it could > be usefully > adapted to work on XML diff languages: > > -1: does not support "very basic" parts of the > Infoset, such as PIs > or comments > 0: supports what can be captured by the Infoset, > except notations > (and perhaps unresolved entities -- under > discussion) > 1: supports everything that is captured by the > Infoset > 2: supports the Infoset plus items that the > Infoset does not take > into account but that cannot be discounted as purely > syntactic (e.g. > element and attribute declarations) > 3: supports the above plus some completely > syntactic constructs, > such as CDATA sections, all the way to perhaps > attribute quote > characters, the variants in empty elements, or the > amount of space > between attributes or between target and data. > > There's still some fair amount of fuzz in there of > course, but I'd be > very interested in feedback on the matter. > > FYI REX could support renaming (by transmitting the > corresponding DOM > mutation events) and batch changes (by using an > XPath selector that > matches several nodes -- this is currently in the > draft but I think > it'll be dropped). > > -- > Robin Berjon > Senior Research Scientist > Expway, http://expway.com/ > > > > ----------------------------------------------------------------- > The xml-dev list is sponsored by XML.org > <http://www.xml.org>, an > initiative of OASIS <http://www.oasis-open.org> > > The list archives are at > http://lists.xml.org/archives/xml-dev/ > > To subscribe or unsubscribe from this list use the > subscription > manager: > <http://www.oasis-open.org/mlmanage/index.php> > > __________________________________________________ Do You Yahoo!? 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