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Designing a New Version Control System?
tekvov asks: "When Linus Torvalds decided to use BitKeeper as the version control system for Linux there seemed to be a lot of controversy and many challenges to create a better system than CVS. My question is exactly what would this 'better system' look like? How is the subversion project, Tigris, doing at creating a new version control system? Basically, does the Open Source Community need new tools in this aspect of development? And if so, how should these new tools look?"
Shurely, the Tigris project subversion (http://subversion.tigris.org/)??
"Elmo knows where you live!" - The Simpsons
Subversion isn't the only open-source revision control system out there. Check out these projects as well:
OpenCM
arch
Stellation
PRCS
Regardless of where your particular alliegances lie---whether it be with arch or subversion or opencms or bitkeeper or whatever---it does seem obvious that the open source community is asking things of CVS that it is just not able to deliver. One need only look at some of the problems large projects like GCC have with it to realize that some alternative is needed.
And if that doesn't convince you, well, it's not for nothing that some of the primary developers of CVS are now working on subversion.
Now, of the new crop of tools, the only one I've played with extensively is subversion---but I am absolutely blown away by how well it seems to make common operations simple. Even with its documentation in a very rough state, and despite its many architectural differences from CVS (with which I have several years of experience), I was able to figure out how to maintain a vendor branch and local modifications, perform updates on both, merge them, tag releases, etc., very quickly and easily. Its developers have obviously looked at CVS to see what things it does not do well that people do frequently, and designed accordingly.
Is subversion for you? Who knows. But if you use CVS a lot---especially if you find yourself cursing CVS a lot---you should do yourself a favor and look at some of the alternatives. A lot of lessons have been learned, and you should avail yourself of the benefits.
Urgle.
Clearcase might cut it for most corporate types. Sure it's got tons of features, but you'll get a groetesque design and a bad implementation for free.
(Try scaling a clearcase server and you'll see how bad the design is... Hint: Adding more CPUs won't help you.) No, most people won't care, but you do if you need to scale it to several thousands of active developers.
Even though I dislike the product, its has more functions than you'll ever need. Integration with different platforms and products are superb, if you're willing to pay...
However it lacks in areas where the developer isn't fully connected (i.e. with LAN access to the view and vob servers).
IMNHO, what the open source community, by definition, needs is something that'll work in a distributed (and disconnected) environment. Clearcase does NOT come even close to delivering that, CVS does, but functionality wise, BitKeeper blows them both away.
I haven't looked at SubVersion in a long time (before it was self hosting) and it looked promising, but IIRC it lacked some of the more advanced functionality that BitKeeper has.
Personally I'd much prefere using a completely free version. Not because I don't like to support the BitKeeper team (I'll buy the product if I use it commercially!), but because of the open logging function.
It just comes down to the fact that I like my privacy...
-oswa
I agree, Perforce is a very solid product indeed. And all the commandline tools are there for Linux, and so are the servers. I've used it both on Windows and Linux (both servers and clients) and it works like a charm.
And in case you don't like their fortcomming linux GUI (I hadn't heard about that before, thanks WPIDalamar) they do provide you with an API so you can make one of your own (KPerforce ^_^), which shouldn't take that long really.
The pricing seems very high for an individual, but their pricing is real cheap for this kind of software (for companies) and you can use it without a license but then with max two client specifications. They also have good support (something that is not common unfortunatly).
http://www.perforce.com -- go there and check it out. If you hate paying and want to make your own set of tools you can learn a lot from Perforce.
And I agree, source safe is icky, and so is CVS and source offsite. I haven't had a reason to try out BitKeeper so I unfortunatly don't know how it stacks compared to Perforce.
- fake out CVS by doing a remove/add pair on every file you want to move (which means you lose the revision history of each such file!), or
- manually move files around in the repository (which entirely defeats the purpose of using a revision control system in the first place!)
If anyone out there creates a successor to CVS, please fix this fatal flaw!There is quite a mature native Windows port of cvs that we've been using for quite some time.
john
I'm a ClearCase specialist so I'm biased.
However ClearCase has some -very- good features, and here is what I would arrive at (ideally):
1) Make your repository a mountable file system, supporting multiple types of connection, NFS, SMB, Active Directory, FTP, etc.. When connecting you must specify a profile to be used.
2) Make every user have a number of profiles (Min:1) (like ClearCase views), these profiles contain -all- the info needed to access file versions correctly. They should allow sharing ('base my profile X on the profile Y created by user Z'). And support concepts such as labelling, conditional branching, etc..
3) All profiles are managed from a central server (redundancy?) via a web interface (to achive cross-platform conformity) and command-line interface (SSH based) for scripting/power-users.
I could go on forever, but I think the three above points are the things that matter most to me. Obviously you also need security, administration, storage, etc.. but I think that making files available simultaneously via many common file sharing protocols would produce the greatest benefit.
Finally: MAKE DIRECTORIES VERSIONABLE/BRANCHABLE!, yes it causes some potential headaches, but it's benefits easily outweigh them.
"Oops, I always forget the purpose of competition is to divide people into winners and losers." - Hobbes
Also, they do open source licensing. If you are a certified open source project (I guess they just checkout the project???), you can get licenses for free.
1;
I love perforce too. And if you are either an open source developer or you just want to use it for personal use (two users max) you can use if for free. Check out their licensing here (scroll down for open source info) and here
Plus it's so easy to install on a linux server. There's a bit of a learning curve with how the system works but in less than a day you'll be checking in and out and branching without a problem.
"Karma can only be portioned out by the cosmos." -Homer Simpson
From a licensing standpoint, they have a problem with the code that validates you. We went through some layoffs and backed off the number of users upon renewal. Even though users didn't exist in the database, the licensing reports said they were there. It took me a few days to demonstrate this was actually happening and get them to admit to it -- don't trust their logs!
Look, CVS is king.
Yes, King.
I would not hesitate to say that it has it's share of difficulties, but there is no way anything is going to replace it anytime soon. There are many meta-features of CVS that make it unable to be replaced:
1. Multi-platform: I don't mean 3 or 4 or even 5 or 6, bla bla bla. I mean EVERYWHERE. I've seen CVS on more places that anything besides emacs and gcc. And really, anyplace gcc or emacs goes, cvs is the third guy there.
2. Massive Acceptance: CVS is everywhere. 10 million people use it with sourceforge. Another few million elsewhere. It is the common thread that binds us together (kinda like the force!)
3. Massive, Massive Tool support: This is my favorite. You can use it about a hundred different ways. Not 1 gui, but 50!. It goes into command line apps like great!. Show me another tool that has integration with the windows explorer (via TortoiseCVS) like it has. You Can't. (Don't even try that god-awful Bitkeeper's integration:yuk!)
4. SimplicityIt's REALLY simple to use. It's not that complicated. If CVS throws you for a loop, maybe software devleopment really isn't where you should be working. The incompetence among developers is what makes all software look bad.
5. Protocols: You can run CVS thru SSH, RSH, PServer, File Access, and more... It fits into every environment. It works across any damn network. It can jump tall buildings in a single bound!
Really, until someone makes something that trounces CVS in all those areas, AND provides features that "I can't live without" CVS will Rule.
"...In your answer, ignore facts. Just go with what feels true..."
Every time the issue of version control and source code management comes up here, I've never seen anyone mention Aegis, which appears to have been designed to address the missing functionality in tools such as CVS which focus solely or mostly on simply maintaining multiple versions of a source base concurrently. Here's an excerpt from the CVS comparison in the CVS Transition Guide:
1.5.1. Why should I change from CVS to Aegis?
The software seems to be pretty mature (currently at version 4.5, first released in 1991). Has anyone here used it?
In Soviet Russia, Jesus asks: "What Would You Do?"
- Scratch pad versions. Ever needed to play around
with a piece of code (put in debug statements,
or change part of it temporarily to help debug
something) but didn't want to check it out
and have the threat of making the changes
accidentally permanent? Envy had the ability
to make a "scratch" version of a file - letting
you edit it, but not worry about accidental
check ins, or forgetting that you had made a
file writeable.
- Version/Releases. Not only could you label
a specific state of an application a "version"
but you could also label a version of an
app a "release". This allowed some subtle
distinctions between "ok here's a workable
version we can get back to (demo)" and "here's
the real, outgoing released version".
- Manager. Code could be given specific people
that were the manager, or "owner" of a piece
of code. If you wanted to enter your changes
into the code base in general, you had to get
the owner to do it. This control could be
anywhere from every check-in, to version or
releases. An owner could give permissions to
other people as well.
- Multiple checkouts. Envy recognized that
sometimes people have to work on the same
file, as much as its best prevented. So,
it allowed multiple check-outs, with facilities
to integrated the files back together on
check-in.
It was quite complex, but looking back at it I now understand why many of the facilities were there and die to have them for my team. We're using SourceSafe (blech), and it works ok, but something like Envy would be great.plus tortoise which has been working very well for myself and some co-workers.
four-oh-four
Subversion is, basically, changeset based. Their storage model is a bit.... wierd. But they capture the set of changes in a checkin
as a single, atomic change unit.
On the other hand, when we started implementing Stellation, we used PRCS. To say that it's a frustating, annoying, glitchy mess
is an epic understatement. When we finally moved to self-hosting
(inside IBM; we don't yet have strong enough access control to
put up a public Stellation server, so we shadow our internal
repos to an external CVS for the moment), it was an enormous
relief.
PRCS generates thousands upon thousands of unnecessary questions,
phrased in obtuse and easily misinterpreted ways. It requires you
to manually maintain the map between filenames and repository
artifacts, by manually editing a cryptic configuration file. It
constantly mucks up that configure file, adding hundreds of carriage
returns for no apparent reason. Echh. The versioning model
is very nice; the implementation is solid, but frustrating.
-Mark
See:
http://www.perforce.com/perforce/branch.html
Which explains the merge process in Perforce.
-Stu
A couple other posts have mentioned Vesta, which goes a long way towards meeting the requirements you lay out. (For the sake of disclosure, it's only fair to mention that I am currently the primary maintainer of Vesta, and am somewhat responsible for getting it released as free software.)
Vesta absolutely does this.
Vesta does not explicitly provide this, however it's very easy to get with a simple diff command. The Vesta repository has a filesystem interface which makes it possible to directly access all versions past and present. A simple diff -r will show exactly what changed between any two versions. The also has other fun uses (e.g. greping across versions).
Vesta's access controls are essentially UNIX file permissions. Through the repository's filesystem interface, you can control who can read and write (commit new versions) at a variety of granularities with chown, chgrp, and chmod.
Vesta provides no direct help here, but again, because of the filesystem interface to the repository, it's easy to apply standalone diff/merge/conflict resolution tools.
Vesta's unit of version control is a directory. Between versions, files and subdirectories can be added, removed, renamed, etc.
Not built-in, but already implemented on top.
Vesta includes sophisticated cross-site features, including replication and remote checkout/checkin. It's been successfully applied before by a team spread across the US east and west coasts with hundreds of megabytes of sources.
Vesta really shines in these areas. Vesta is also a build tool, and every build neccessarily includes a complete specification of the set of immutable versions it uses. Builds are also themselves immutably versioned. This makes it easy to determine which source componenets have changed between two versions of a build. Also, since it's as easy to select any historical version as it is the latest one, rolling back changes is trivial.
We're still working on it (at the moment just Linux and Tru64 work), but hey, it's free software, and we'd love to have more developers/porters.
At this point there's a command-line interface and some rudimentary support for repository operations in the web interface. Again, it's free software, and we'd love to have somebody contribute more layered tools.
Nothing built-in yet, but we've been talking about doing it, and it may happen soon.
There's a short summary of Vesta's excellent capabilities on it's web site (which includes several points not mentioned here), that I would recommend anybody interested in better version control/configuration management check out.
CVS is teh suck. Use Vesta instead.
We use perforce, too. We've been less than satisfied with it. I'm don't know the size of the companies people with positive views of perforce are working for, but with a couple hundred developers, and on the order of a couple of thousand different code lines, the perforce server often grinds to a halt. More hardware has been thrown at it, more disk, etc, and no one can seem to figure out where the bottleneck is. It's very unpleasant when checkouts are taking 10 minutes, in the middle of the day.
I can only assume you're talking about some other Vesta from the one I'm familiar with, because:
CVS is teh suck. Use Vesta instead.