Re: Xdelta and CVS

[Greg A. Woods]

[ On Friday, April 20, 2001 at 08:23:24 (-0700), Stephen Rasku wrote: ]
> Subject: Re: Xdelta and CVS
>
> I would agree with this.

Unfortunately the network interface to CVS is only one facet of a CVS
repository, and there are several subtle interdependencies between RCS
and that protocol.

One other attribute of RCS files that's important to CVS is that there
is a single file for every source file and the entire history for every
source file is self-contained in that single file.  Obviously this
attribtue would apply to SCCS files too.

> This is irrelevant.  I converted an SCCS repository to a CVS repository 
> and RCS compatibility was (obviously) not required to do this.  It 
> wouldn't matter what file format CVS stored its files in if I have a tool 
> to convert from my existing source control file format.  

It's probably important to note that if you were using SCCS "properly",
and you were making any significant use of its full feature set, then
you almost certainly lost important history information during the
conversion (unless you used an unpublished conversion process --
i.e. not the sccstorcs script included with CVS).

In any case you've proved my point -- the conversion tools must come
along with any new repository format.  CVS didn't need any conversion
tools when it was introduced because it was intended for RCS users in
the first place.  Writing such conversion tools correctly is a
non-trivial task and requires a deep understanding of both the source
and destination structures and semantics.  Remember too that unless such
a new format is truly successful and purvasive the conversion tools
would have to be bi-directional.  In the case of CVS using RCS the
conversion from SCCS to RCS was the only important direction because RCS
itself was purvasive enough that even if you decided to ditch CVS you
still wouldn't have had to go back to using SCCS because you could
equally well have continued using just RCS.

So, who's got 6 months to a year or more of free time to design and
build a CVS replacement that uses Xdelta and build bi-directional
conversion tools for efficient and save conversion to and from an
RCS-based CVS repository?  You might even get me to use it if I can be
assured that my repository can be converted and assuming that it has all
the other CVS attributes I depend upon.

Meanwhile the BitKeeper folks have apparently written CVS conversion
tools, and someday I might just try using their stuff instead of CVS.
The only problem is that it see they've failed as yet to provide an
inverse conversion tool.

-- 
                                                        Greg A. Woods

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