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Re: A different option for a new XML delta format

From: Karl Fogel <kfogel_at_galois.collab.net>
Date: 2000-10-03 20:35:39 CEST

Yes... I'd like to spend some serious thought on this, but only after
we've passed Milestone 1 (even though that may mean implementing
things one way and then reversing ourselves later, still I don't think
we'll go too far out on a limb).

If we were to change the XML format now, there would be absolutely no
chance of having that milestone (checkout/filemod/add) working by the
end of the week.

-K

Greg Hudson <ghudson@mit.edu> writes:
> (Sorry to flood people's inboxes... I'm a little verbose when it comes
> to design issues.)
>
> After thinking about the general unreadability of my proposed format,
> I thought I would go through and make a DTD and sample delta for Greg
> Stein's XML format proposal. If you go to the end of this message and
> look at the sample, you can see that it's considerably more readable,
> although it's maybe less clear to the uninitiated that you need to
> "add-file" or "replace-file" before you can "text-delta".
>
> >From an implementation perspective, this approach is about the same,
> except that the lookup strings for file and directory batons are parts
> of the pathnames. For instance, when the parser runs into something
> like:
>
> <add-dir path="/A/B/C"/>
>
> it will rip apart the path into a parent directory "/A/B" and a new
> directory name "C". "/A/B" will be used to look up the parent
> directory baton. For file-editing calls like text-delta, the entire
> path gets used as a lookup string for the file baton.
>
> Comparison:
>
> * Greg Stein's approach is more readable.
>
> * Greg Stein's approach becomes really verbose when directory
> names get long. My approach doesn't have this problem
> because IDs can be a lot shorter than pathnames.
>
> * My approach makes the constraints clearer, since you can't
> try to <text-delta> a file before you specify an ID for it.
>
> * My approach is a little cleaner from an implementation point
> of view since you don't have to rip apart paths. (But there
> is a middle-ground approach where you specify the parent
> path and directory element in separate attributes, so if
> this is a real issue it only requires a tweak to my
> rendition of Greg Stein's proposal.)
>
> So, opinions? At the moment I'm leaning in favor of Greg Stein's
> approach, long directory names be damned. But I'll take a break for a
> few hours and let people catch up before I start trying to crank out
> an implementation.
>
> <?xml version="1.0" encoding="UTF-8"?>
> <!-- XML DTD for Subversion's delta packages. -->
>
> <!ELEMENT delta-pkg (delete | add-dir | replace-dir | change-dir-prop
> | change-dirent-prop | close-dir | add-file
> | replace-file | text-delta | change-file-prop
> | close-file)*>
>
> <!-- delete-dirent: delete a directory entry -->
> <!ELEMENT delete-dirent>
> <!ATTLIST delete-dirent
> path CDATA #REQUIRED
> >
>
> <!-- add-dir: Create a new directory -->
> <!ELEMENT add-dir>
> <!ATTLIST add-dir
> path CDATA #REQUIRED
> ancestor CDATA #IMPLIED
> ancver CDATA #IMPLIED
> >
>
> <!-- replace-dir: Modify a directory -->
> <!ELEMENT replace-dir>
> <!ATTLIST replace-dir
> path CDATA #REQUIRED
> ancestor CDATA #IMPLIED
> ancver CDATA #IMPLIED
> >
>
> <!-- change-dir-prop: Edit the properties of a directory -->
> <!ELEMENT change-dir-prop (set | delete)+>
> <!ATTLIST change-dir-prop
> path CDATA #REQUIRED
> >
>
> <!-- change-dirent-prop: Edit the properties of a directory entry -->
> <!ELEMENT change-dirent-prop (set | delete)+>
> <!ATTLIST change-dirent-prop
> path CDATA #REQUIRED
> >
>
> <!-- close-dir: Indicate that we are done with a directory -->
> <!ELEMENT close-dir>
> <!ATTLIST close-dir
> path CDATA #REQUIRED
> >
>
> <!-- add-file: Create a new file -->
> <!ELEMENT add-file>
> <!ATTLIST add-file
> path CDATA #REQUIRED
> ancestor CDATA #IMPLIED
> ancver CDATA #IMPLIED
> >
>
> <!-- replace-file: Modify a file -->
> <!ELEMENT replace-file>
> <!ATTLIST replace-file
> path CDATA #REQUIRED
> ancestor CDATA #IMPLIED
> ancver CDATA #IMPLIED
> >
>
> <!-- text-delta: Edit the text of a file -->
> <!ELEMENT text-delta (#PCDATA)>
> <!ATTLIST text-delta
> path CDATA #REQUIRED
> >
>
> <!-- change-file-prop: Edit the properties of a file -->
> <!ELEMENT change-file-prop (set | delete)+>
> <!ATTLIST change-file-prop
> path CDATA #REQUIRED
> >
>
> <!-- close-file: Indicate that we are done with a file -->
> <!ELEMENT close-file>
> <!ATTLIST close-file
> path CDATA #REQUIRED
> >
>
> <!-- set: Set a property's value -->
> <!ELEMENT set (#PCDATA)>
> <!ATTLIST set
> name CDATA #REQUIRED
> >
>
> <!-- delete: Delete a property -->
> <!ELEMENT delete EMPTY>
> <!ATTLIST delete
> name CDATA #REQUIRED
> >
>
> <?xml version="1.0" encoding="UTF-8"?>
> <delta-pkg>
> <add-dir path="/A" ancestor="/A" ancver="1"/>
> <add-file path="/A/mu" ancestor="/A/mu"/>
> <text-delta path="/A/mu">This is the file 'mu'.</text-delta>
> <close-file path="/A/mu"/>
> <add-dir path="/A/B" ancestor="/A/B"/>
> <add-file path="/A/B/lambda" ancestor="/A/B/lambda"/>
> <text-delta path="/A/B/lambda">This is the file 'lambda'.</text-delta>
> <close-file path="/A/B/lambda"/>
> <add-dir path="/A/B/E" ancestor="/A/B/E"/>
> <change-dir-prop path="/A/B/E">
> <set name="car">buick</set>
> </change-dir-prop>
> <close-dir path="/A/B/E"/>
> <add-dir path="/A/B/F" ancestor="/A/B/F"/>
> <change-dir-prop path="/A/B/F">
> <delete name="glub"/>
> </change-dir-prop>
> <close-dir path="/A/B/F"/>
> <close-dir path="/A/B"/>
> <add-dir path="/A/C" ancestor="/A/C"/>
> <close-dir path="/A/C"/>
> <add-dir path="/A/D"/>
> <add-file path="/A/D/gamma" ancestor="/A/D/gamma"/>
> <change-file-prop path="/A/D/gamma">
> <set name="banana">yellow</set>
> <delete name="lemon"/>
> <set name="crabgrass">epistemological</set>
> </change-file-prop>
> <text-delta path="/A/D/gamma">This is the file 'gamma'.</text-delta>
> <close-file path="/A/D/gamma"/>
> <close-dir dir-id="/A/D"/>
> <close-dir dir-id="/A"/>
> </delta-pkg>
Received on Sat Oct 21 14:36:10 2006

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