[Zope-Coders] Re: [ZODB-Dev] Re: revising layout of ZODB3 checkout

[Shane Hathaway]

On Fri, 9 Jan 2004, Ken Manheimer wrote:

> It's probably worth looking over two comparison charts findable from
> the URLs jeremy mentioned:
> 
>   http://better-scm.berlios.de/comparison/comparison.html
>   http://gnuarch.org/bin/view/Main/SubVersionAndCvsComparison
> 
> In the first, subversion looks quite good, while the second, from the
> 'arch' development site, arch looks better.  While the lack of
> corroboration between the two might be frustrating, tracking through
> the discrepancies might make for a useful focus.

I'm glad comparisons are finally starting to appear.  Here's what I gather 
from those documents.

>From the 1st comparison:

- Subversion has "svn diff", similar to "cvs diff".  Arch doesn't yet have
an equivalent.  That's surprising.

- Subversion's documentation is more mature than Arch's.

- Subversion requires a few more libraries.  Two years ago people were
concerned about Gnucash for a similar reason.  It depended on recent
versions of 60 large libraries, so everyone had a hard time installing it.  
Yet Gnucash thrives today.  I think library requirements are irrelevant.

  http://lwn.net/2001/0614/
  http://plope.com/Members/chrism/gnucash_is_good

- Subversion takes less effort to learn because it uses a command set 
similar to that of CVS.  Arch uses different conventions.

- Subversion is portable to Windows by design.  Arch is designed for Unix,
though a compatibility layer is available.

- Many GUIs are already available for Subversion.  Arch only has a 
work-in-progress Web UI.


>From the 2nd comparison:

- Arch has advanced merging features that Subversion does not.  How much
better can it be, though?  Merging is difficult because people make
incompatible changes.  Only humans can resolve actual conflicts.

- Subversion and Arch both support branches, but as before, Arch has
advanced merging features.

- Subversion doesn't yet have a script to generate ChangeLog files.  
(Surely someone will write it.)

- With Arch, all revisions are accessible as regular files.  With
Subversion, revisions are accessible via WebDAV. (davfs anyone? ;-)

- Arch supports private repositories very well.

- The other two columns of the table ("easy" and "scalable") are too
subjective.


Subversion seems much more mature than Arch, perhaps because there are
more people in the Subversion camp.

The one major advantage Arch has over Subversion is the strong support for
distributed repositories.  If I understand it correctly, it's a very cool
concept.  Let's say you want to make changes to the Zope source and check
in those changes so others in your company can get them, but you're not
ready to check in to the main tree.  With Arch, that's no problem--just
make a repository within your company that mirrors the main tree.  With
CVS, you'd need to hassle with vendor imports.  I don't know what you'd do
with Subversion.

BitKeeper is tied up in a big political battle over free vs. non-free.  
We don't need that.  Aegis requires NFS for remote communication, so it
doesn't suit open source development.  Monotone and OpenCM are new 
competitors with potential.

Shane