== Introduction ==

This directory contains a simple plugin that adds 
Subversion (http://subversion.tigris.org/) branch support to 
Bazaar (http://www.bazaar-vcs.org/)

== Dependencies == 

You will need at least version 0.13 of Bazaar-NG (currently unreleased).

You also need a fairly recent version of the Python bindings to the 
Subversion libraries. At the moment, the svn plugin only works with 
Subversion 1.5 (trunk). The python-subversion package in Ubuntu Edgy and 
Debian Sid also contains the required changes.

== Features ==

The following features are currently present:

 * Connecting to remote Subversion repositories over all 
   protocols supported by Subversion itself (at present: 
	svn://, svn+ssh://, http:// (webdav), file://) 
   as well as dump files. 

   Checkouts, lightweight checkouts and branching works.

 * Track Bazaar merges in Subversion. Merged revisions show up 
   as ghosts.

 * Subversion working copies. Can be modified, queried 
   (`bzr status' on a vanilla working copied created with 
	`svn co' works) and committed from.

 * Committing to Subversion from Bazaar.

 * Push Bazaar revisions to Subversion. These revisions will 
   show up in Subversion as a commit with the pushed revision 
   as one of the parents.

 * Follow branch copies. Revision history is not 
   truncated when a branch was copied in Subversion.

 * Efficiently uses network bandwidth. 

 * Recognizes file metadata (executable bits, symlinks).
 
 * 'import-svn' command with functionality similar to svn2bzr.

 * Ability to track merges done with SVK (http://svk.elixus.org/) 
   and write merges.

 * Generates consistent file ids and revision ids. Two branches made using 
   this plugin of the same Subversion branch will result in *exactly* the same 
   Bazaar branch.

 * Handles complex operations in Subversion: committing to two branches at 
   once, upgrading directories to branches, copies from early revisions, ...

== Future Enhancements ==

In the future, I also hope to support:

 * Renames. Initial work has been done to support this, 
   but the number of corner cases is wide, so support for this 
   has not been enabled by default yet.

   Those brave enough can test the current support out by 
   registering SvnRenamingRepository instead of 
   SvnRepository in __init__.py.

 * "True" push. This requires storing the Bazaar 
   inventory and revision in Subversion revision properties.

   Ideally, revision id aliases would have to be used so the 
   revision id that is being 'overriden' can still exist.

   Once this is implemented, it would also be possible and 
   make sense to store GPG signatures for commits in 
   Subversion branches.

   This might require also storing 'bzr:inventory' and 'bzr:revision' 
   properties in order to make sure the sha1's for a revision keep matching.

 * Proper read locking, which has basically been ignored for now. 

 * Performance. Network-wise (both bandwidth and roundtrips), the plugin is in
   good shape. However, it is currently quite CPU-intensive for no good reason 
   and I hope to make a couple of improvements in that area.

	 * Override implementation of get_revision_delta(). Will speed up 'bzr log -v'
	
	 * use svn_ra_replay() on systems that have Subversion 1.4. Saves a couple of roundtrips when fetching history.

	 * implement svn_ra_get_dir_revs() in Subversion to fetch the properties set on a specific directory all at once.

 * Creating native Subversion working copies. This 
   would mostly be supported for completeness' sake, there are not 
   a lot of advantages in supporting it.

Some Subversion properties can currently not be represented in Bazaar 
and are therefore ignored for the time being:

 * `svn:ignore' is not imported. There should be a 
   `Repository.get_ignores(revid)' call in Bazaar rather than a magic 
   '.bzrignore' file. 
   
 * `svn:externals'. Externals should be mapped to Bazaar 'by-reference' 
   nested branches and the other way around. This can't be implemented 
   this until Bazaars nested branch support lands. AaronBentley's work 
   in progress is at http://code.aaronbentley.com/bzr/bzrrepo/nested-trees/.
   This has been delayed until after 0.9 because of required repository
   format changes.

 * `svn:mime-type'

 * `svn:eol-style'

 * `svn:keywords'. Requires keywords support in Bazaar. Spec at 
   https://launchpad.net/products/bzr/+spec/bzr-keyword-expansion

Other features currently held back by Bazaars feature set:

 * Horizon revision history. Most of the existing Subversion repositories 
   are quite large and it would therefore be nice to be able to limit 
   the amount of history that needs to be retrieved during checkouts.

 * Tracking copies. 
 
   Spec at https://launchpad.net/products/bzr/+spec/filecopies

Features held back by Subversion:

 * Showing SVN merges as merges in Bazaar. This requires full merge tracking 
   information in Subversion, something which the Subversion folks are working 
   on at the moment (see https://svn.collab.net/repos/svn/branches/merge-tracking).

   Might require cherry-picking support in Bazaar (or at least the ability 
   to know about cherry picks). 
   
   Spec at https://launchpad.net/products/bzr/+spec/bzr-cpick-data

== Bugs ==
 
Please file bug reports in launchpad. The product URL for bzr-svn is
https://launchpad.net/products/bzr-svn/. The wiki for this 
plugin is at http://bazaar-vcs.org/BzrSvn.

== Installation ==

Simply place this directory in ~/.bazaar/plugins and you should be able 
to check out branches from Subversion using bzr.

== License ==

GNU General Public License, v2 or later.

== Unit testing ==

Simply run 'bzr selftest svn'

== Author ==

Jelmer Vernooij <jelmer@samba.org>