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6 by mbp at sourcefrog
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Ideas from Aegis
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* Very mature -- in use for 14 years, many large projects, etc.
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* "Essential process can be learned in a day" -- which is still kind
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  of a long time; i'd like it to be well under an hour.
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* Good process integration; show who is supposed to be working on what
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  and how far through they are.
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* Very poor Windows support.
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* Distributed repositories. (??)
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* Very focussed on security -- can reproduce any previous revision;
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  availability/integrity/confidentiality; uses Unix permissions and
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  seteuid() to prevent users changing the database.
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* Does not itself track history -- assumes this will be done by some
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  other tool such as RCS operating on the baseline.
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* I think every individual project needs a single baseline. (??)
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* The baseline is always working and always releasable -- to the
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  extent that you have scripts which can enforce this.
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* Integration step is somewhat similar to that used by distributed
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  systems.  It seems that you could build some features of aegis as
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  policy macros on top of Bazaar-NG.
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* The baseline also contains object files built from current source,
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  which can be used to pre-populate working directories.  Also people
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  only need a copy of the source files they're changing.  I think the
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  economics of this have changed a bit.  Also tends to assume all
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  developers are on the same Unix host, which is no longer generally
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  true.
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* Only one review/integration can be in process at a time.
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* One process difference is that developers produce all changes;
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  reviewers/integrators can only accept or reject them.  This is
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  different from the integrator-makes-right model of many distributed
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  tools.  (Though the integrator still has the choice to reject, but
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  they have the option of fixing it too.)
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* Can automatically append Signed-off-by field.  Interesting idea.  I
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  wonder if we should have a metadata facility to include licence
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  data?
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* Much of the functionality of Aegis is to prevent people doing things
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  they could otherwise do.  That can be useful in enforcing a healthy
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  process but bazaar-ng is not the place for it. 
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* Can serialize an (in-progress) changeset to text, and then mail from
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  one place to another.
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* Branches are an extension of the 'change' concept; they can be
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  merged into the parent in the same way that a change can be.
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  Merging branches onto the mainline seems to hit a similar problem to
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  that of centralized branches.  If someone else has committed, you
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  need to make a new changeset reconciling all their changes, commit
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  that to the child branch, then commit everything to the parent.
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  This suggests a different way to do shared branches in Bazaar-NG:
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    You can push to the parent if you incorporate either directly or
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    by merger all changes on the parent.  That means that everything
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    someone has committed to the parent is present in some way in your
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    branch.  By extension, it is safe to transform the parent text
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    into your branch without losing anything.  We can therefore
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    remotely record that changeset to the parent.  This is more or
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    less what Aegis does.
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    The problem with this in the Bazaar-NG model is that then the new
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    commit will be only in the parent, and not on the child.  So if
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    you run ``bzr log`` on the child, you won't see what you just
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    committed.  We can't apply it to both because the predecessor is
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    different.  (darcs could do that, but it has a looser patch
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    history than I want.)
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Overall, the process model is good for a particular type of
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organization.  It would be good to build this on top of Bazaar-NG.  To
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support that we need:
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 - patches are submitted, rather than being directly written in 
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 - arbitrary levels of branching/review
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 - users can submit changes to branches they are not directly allowed
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   to write to 
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 - branches can be cleanly removed when they're no longer necessary
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 - strong audit trail
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Interestingly, the BitKeeper model which is criticized__ by Greg
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Hudson is similar to that of Aegis: a single integrator (or small
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team?) who ultimately decide what gets into the main tree.
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__ http://web.mit.edu/ghudson/thoughts/bitkeeper.whynot
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The Aegis workflow can probably be `emulated in bzr <workflow.html>`_.