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Subversion Hits Alpha
C. Michael Pilato writes: "This overheard while eavesdropping on announce@subversion.tigris.org: Gentle coders, The ever-growing cadre of Subversion developers is proud to announce the release of Subversion 'Alpha' (0.14.0). Since we became self-hosting eleven months ago, we've gone through ten milestones. This milestone, however, is the one we've always been working towards; it's a freeze on major features for our 1.0 release. From here out, it's mostly bug-fixing. We hope this announcement will lead to more widespread testing; we welcome people to try Subversion and report their experiences on our development list and issue tracker." Subversion, a source control system akin to CVS, has been in the works for a couple of years now.
It would be more accurate to say subversion:CVS::mozilla:netscape4. Subversion is intended to replace CVS, and it's core team is made up many of the people that currently maintain CVS. CVS has really reached the end of its life cycle; its really showing its age, and it just doesn't make sense to extend it anymore. No, this is not a "CVS is dying" post, but anyone who has adminned it has been frustrated with it from time to time, and Subversion aims to remedy that. They're keeping what's good about CVS and replacing the bad with better things based on decades of experience with CVS and improvements in the SCM field in general.
This is intended to be a replacement for CVS. No less, and no more (for the "more", see some of the more experimental SCM stuff like Tom Lord's arch).
Surely the easiest way of finding out is to visit the website. From the front page:
Directories, renames and file meta-data are versioned.
Commits are truly atomic.
Apache as network server, WebDAV/DeltaV for protocol
Branching and tagging are cheap (constant time) operations.
Natively client/server, layered library design.
Client/server protocol sends diffs in both directions.
Costs are proportional to change size, not data size.
Efficient handling of binary files.
Parseable output.
For more details, see the website.
Jon
What is so bad about clearcase? From my point of view what *isn't* bad about clearcase is an easier question. Here's my hot list:
1. Needs kernel modifications in order to work. PROFOUNDLY STUPID. It's always an adventure trying to get clearcase to work with any recent linux kernel, and forget trying to keep current with kernel security patches.
2. "Filesystem" style sharing does not scale well outside of a high speed, local network. If your developers are distributed around the internet you need to use clearcase's horrible hack "snapshot" views, or shell out ridiculous amounts of money and complexity to implement multisite. It's very difficult from a performance and a security standpoint to use clearcase over a low-speed VPN.
3. Good GUI administration tools are windows-only. While rational could have created cross platform admin tools when they ported their product to Windows, they didn't. Instead they rewrote their admin tools to be windows only, added many new features, and now the windows tools are 200X more usable than their unix equivalents. When I pressed irRational when the unix tools would be similarly improved they gave the patronizing answer that unix customer's don't want good admin tools. Sounds like a self fullfilling prophesy to me. The unix GUI tools are so awful that it is easier to use the command line! Thus, irRational insures that unix shops with clearcase will always have a brick-wall style learning curve.
4. Vobs don't scale well, especially when you version large binary files, like media. You have to manually tune how many vobs to use and how large to make them.
5. Relies on automounting and persistent filesystem connections for day-to-day work. This design is inferior to a more traditional client-server TCP/IP app in terms of both performance and robustness.
6. Lack of commitment to the unix platform. iRational has stopped future development on their unix bug tracking software (DDTS) in favor of a MS-ACCESS backed solution. A large majority of new clearcase features are windows-only. You would think that Rational would be a cross platform company, but they are not. They make platform-specific solutions for multiple platforms, most of them purchased from some other company and poorly maintained.
7. Extremely high maintenance costs, not just in the licensing but in the dedicated personel needed to throw their careers away doing nothing but babysitting the vobs and views.
If you're buying a proprietary CMS the last thing you should consider is iRational clearcase. Try bitkeeper or perforce and you'll be much happier.
We've got python bindings for parsing RCS files, and bindings to subversion libraries (via SWIG). As a result, we now have a good start on a 'cvs2svn.py' repository-converter script.
The script examines the cvs repository, deduces changesets, and commits them to an svn repository. It works right now.
However, it doesn't yet convert cvs branches and tags. We're working on it.