Re: Subversion with multiple read/write replicated repositories

Kis Gergely wrote:

> I would like to recommend subversion to my company, but there is one feature
> subversion is currently lacking: the support for multiple replicated
> repositories. The approaches known to me (svn::Mirror, Svn::Push, svn-push)
> are not sufficient, because I need two way synchronization.

See also svk:

        http://svk.elixus.org/

which does support two-way mirrors, but possibly not in the way you expect.

> A maximum synchronization lag of 1-2 hours may be acceptable.

This is never going to be 100% automatic if you are permitting writes to more
than one repository (due to possible conflicts).

> The revision numbers should be preserved across the repositories.

This is going to be the biggest problem, because the revision number is merely a
monotonically increasing value. You cannot commit on one mirror and
simultaneously commit to another and have the revision numbers mesh (without
doing what you suggest and have multiple blocks of revision numbers which are
only used for commits.

If you can lose this constraint, you can get very close today with svk certainly
and thus SVN::Mirror. IMHO, the revision number is an artifact of the
repository structure and it should not be used as an external datapoint (say to
retrieve a specific set of files) except in very restrictive circumstances.
Good tagging procedures serve this need very well. Similarly, the CVS
$Revision$ tag was never intended to be used as a file version (though many
people have done so over the years).

> It should be possible to commit in the local repositories even if the network
> links to the other repositories are down. The system should support 10 or
> more connected repositories - I am thinking of a hierarchical approach.

svk supports disconnected transactions.

HTH

John

-- 
John Peacock
Director of Information Research and Technology
Rowman & Littlefield Publishing Group
4501 Forbes Boulevard
Suite H
Lanham, MD  20706
301-459-3366 x.5010
fax 301-429-5748
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