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RE: Locking support

From: Greg A. Woods
Subject: RE: Locking support
Date: Wed, 22 Aug 2001 22:05:18 -0400 (EDT)

[ On Thursday, August 23, 2001 at 08:48:06 (+1000), Ellison, Martin [IT] wrote: 
> Subject: RE: Locking support
> Are there any other freeware tools for version control?

Sure!  Lots!

RCS and CSSC (the free GNU implementation SCCS), or MySC (from which
CSSC was derived) are freely available.....

> Where do I find
> about Aegis and TCCS? 

On the WWW, for one:

There's also a good 1/3 or more of the O'Reilly book "RCS and SCCS"
actually dedicated to describing TCCS.

You might also find something else here:

such as:


> I'm not interested in CVS because it can do concurrent edits. I'm interested
> because CVS is a stable version control system that supports multiple
> platforms (and because it's freeware).

CVS was explicitly designed to effectively *force* developers into a
concurrent editing scenario.  Fight that design at your peril.

If you do not want to be forced into using a versioning system that only
really supports concurrent editing then you do not want CVS, no matter
how free or stable or otherwhise suitable it is for your project.

CVS is not the only kid on the block.  Indeed if concurrent edits are
antithetical to your group then even bare RCS or SCCS would be preferable.

> Should we modify the people to suit the software or the software to suit the
> people?

If CVS is realy your only viable solution then you must modify the people.

If you don't want to modify the people then you must find a more
suitable versioning system, or else write one yourself (re-engineering
CVS to for mandatory locking would ultimately amount to *more* work than
just writing something more suitable from scratch).

Note that several very successful commercial version control systems
have proven time and time again that concurrent editing with
semi-automatic conflict management (as with CVS), is highly successful.
Two such tools are Sun's TeamWare and their NSE which preceeded it.  If
you do some searches on the WWW you'll find several testimonials as well
as numerous research papers and tech reports describing the successes of
concurrent editing.

Even one of the few "white papers" you'll find on the WWW that tries to
scare programmers about the "dangers" of automatic merging usually done
by concurrent editing version control systems or systems that support
merging of branches still agrees that automatic merging is generally

   In practice this works very well.  In a large majority of the cases,
   the changes made by the programmers are so independent that no
   conflicts arise from this process.  Of the remaining cases, most have
   conflicts that are so obvious that it is trivial to spot them even
   with "automated" programs.  These cases require human intervention
   because of the conflicts and a programmer is then called in to
   examine both change sets and mediate between the two.

Of course the author then goes on from there to raise fearful issues in
an effort to try to sell you his "MergeRight" tool!  If you have fears
about the merging CVS does, perhaps you should consider purchasing such
a tool....  :-)

                                                        Greg A. Woods

+1 416 218-0098      VE3TCP      <address@hidden>     <address@hidden>
Planix, Inc. <address@hidden>;   Secrets of the Weird <address@hidden>

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