How to structure a VCS with multiple dependent projects - version-control

I'm sure that this is a common issue that other have solved before so I'm calling on the collective wisdom of other developers/project managers out there for some help.
I've got a number of projects:
Application
WebApp
ServerApp
Dev Utils
ORM
All of the apps/utils depend on the ORM: When the ORM changes, it needs to be compiled and all of the apps need to be re-compiled against it and then deployed. Right now my VCS structure is kind of a jumble:
AppName
Trunk
Application
WebApp
ServerApp
Dev Utils (around 4 folders right now, but growing)
ORM
Relase
ProjectName (be it Application or WebApp) version.number
Branches
ExperimentName_DevName
Ideally, I'd like to have a root folder per application (Application/WebApp/ORM etc.), each with its own Trunk/Branches/Releases etc. to logically and physically separate them. My reasoning is that because lots of work gets done on the Application, and it gets released far more often, each release branch has identical copies of the same utils etc. Also checking out the Trunk to work on it always means that all of the other projects come along for the ride.
However, separating would mean ripping certain projects out of solutions and making modifying any projects simultaneously a pain - jumping between 2-3 IDEs (especially when making changes to the ORM).
I'm thinking about this because very soon I'm putting together a CI machine (be ready for questions about that in a week or so) and I'm trying to figure out a way to have the releases automatically created/deployed. Normally, just the Application gets deployed, via script copy to the server where all of the workstations pull from on startup, but like I said before, if the ORM changes/releases, all of the other apps should re-build and deploy.
(Today I broke our website and 3 utilities cause I changed the ORM and deployed it with an updated version of the Application, but forgot to rebuild/deploy the other apps with the new ORM - oops.)

Put yourself in your developer's shoes. This shouldn't be hard because it sounds like you're one of them :-) Look at your version control layout not from an architectural point of view, but from a usability point of view. Ask yourself: on a daily basis what are the most common things that we as developers do with our source code? Think specifically with regards to your interactions with your VCS system and the project layouts. You want to make the common things brain-dead easy. It's ok for the less common use cases to be harder to get to, as long as you have a record of how to do them, so that when (not if!) people forget, they'll know where to look to remind themselves how.
I've seen a lot of VCS layouts that try to be architecturally "perfect", but end up causing no end of hassles and headaches from a day-to-day usage point of view. I'm not saying the two can't coincide and mesh well together, I'm just saying think about it from the users point of view, and let that be your guide.
From a CI point of view, I'd still take this approach. Even if your setup ends up becoming more complex to define in your CI of choice, you only have to do the setup there once. If the layout is easy to use during development, most of your CI setup should also be relatively easy. You then just focus on the last bits that will take more time.

Splitting up your code base into different "projects" can be very difficult. We have done this at each separately "deployable" boundary. Including a "platform" layer that is common/used by the others, as a separate project. But this isn't really perfect either.
The one thing that I cannot stress enough is that one needs to have some form of continuous regression/testing that runs after checkins and before you actually deploy anything. In addition a "release" process that might even involve some manual testing can be helpful and has definitely prevented a few egg on the face situations. (Better to release it a couple days late then broken.)
(Sorry to not directly address your problem)

Related

Source control Branching needs

we are creating hospital information system software. The project will be different hospital to hospital and contain different use cases. But lots of parts will be the same. So we will use branching mechanism of the source control. If we find a bug in one hospital, how can we know the other branches have the same bug or not.
IMAGE http://img85.imageshack.us/img85/5074/version.png
The numbers in the picture which we attached show the each hospital software.
Do you have a solution about this problem ?
Which source control(SVN,Git,Hg) we will be suitable about this problem ?
Thank you.!
Ok, this is not really a VCS question, this is first and foremost and architectural problem - how do you structure and build your application(s) in such a way that you can deliver the specific use cases to each hospital as required whilst being able, as you suggest, to fix bugs in commom code.
I think one can state with some certainty that if you follow the model suggested in your image you aren't going to be able to do so consistently and effectively. What you will end up with is a number of different, discrete, applications that have to be maintained separately even though they have at some point come from a common set of code.
Its hard to make more than good generalisations but the way I would think about this would be something along the following lines:
Firstly you need a core application (or set of applications or set of application libraries) these will form the basis of any delivered system and therefore a single maintained set of code (although this core may itself include external libraries).
You then have a number of options for your customised applications (the per hospital instance) you can define the available functionality a number of means:
At one extreme, by configuration - having one application containing all the code and effectively switching things on and off on a per instance basis.
At the other extreme by having an application per hospital that substantially comprises the core code with customisation.
However the likelyhood is that whilst the sum of the use cases for each hospital is different individual use cases will be common across a number of instances so you need to aim for a modular system i.e. something that starts with the common core and that can be extended and configured by composition as much as by any other means.
This means that you are probably want to make extensive use of Inversion of Control and Dependency Injection to give you flexibility within a common framework. You want to look at extensibility frameworks (I do .NET so I'd be looking at the Managed Extensibility Framework - MEF) that allow you to go some way towards "assembling" an application at runtime rather than at compile time.
You also need to pay attention to how you're going to deploy - especially how you're going to update - your applications and at this point you're right you're going to need to have both your version control and you build environment right.
Once you know how you're going build your application then you can look at your version control system - #VonC is spot on when he says that the key feature is to be able to include code from shared projects into multiple deliverable projects.
If it were me, now, I'd probably have a core (which will probably itself be multiple projects/solutions) and then one project/solution per hospital but I would be aiming to have as little code as possible in the per hospital projects - ideally just enough framework to define the instance specific configuration and UI customisation
As to which to use... if you're a Microsoft shop then take a good long hard look at TFS, the productivity gains from having a well integrated environment can be considerable.
Otherwise (and in any case), DVCS (Mercurial, Git, Bazaar, etc) seem to me to be gaining an edge on the more traditional systems as they mature. I think SVN is an excellent tool (I use it and it works), and I think that you need a central repository for this kind of development - not least because you need somewhere that triggers your Continuous Integration Server - however you can achieve the same thing with DVCS and the ability to do frequent local, incremental, commits without "breaking the build" and the flexibility that DVCS gives you means that if you have a choice now then that is almost certainly the way to go (but you do need to ensure that you establish good practices in ensuring that code is pushed to your core repositories early)
I think there is still a lot to address purely from the VCS question - but you can't get to that in useful detail 'til you know how you're going to structure your delivered solution.
All of those VCS (Version Control System) you mention are compatible with the notion of "shared component", which allows you to define a common shared and deployed code base, plus some specialization in each branch:
CVCS (Centralized)
Subversion externals
DVCS (Distributed)
Git submodules (see true nature of submodules)
Hg SubRepos
Considering the distributed aspect of the release management process, a DVCS would be more appropriate.
If the bug is located in the common code base, you can quickly see in the other branches if:
what exact version of the common component they are referring to.
they refer the same or older version of that common component than the one in which the bug has been found (in which case chances are they also do have the bug)

How can I convince my department to implement a version control system?

I recently joined the IT department of a big insurance company. Although the department's title is "IT", a lot of code gets written here; Java, JSP, JavaScript, COBOL and even some C++ from what I've heard. All the programs that allow insurers, brokers and the rest of the tie-wearing, white-collar workers to issue new contracts and deal with clients runs on the code produced by this department. I've been told that the department is pretty good by the parent company's standards and that we've even received an internal award or two. We're 17 people in the department, split in smaller groups of 2 or 3. As you might've guessed from the COBOL part further up, the average age is over 40 years (as a point of reference I'm 29 yo).
Right now, there is no version control system in place (there exists a general backup scheme though). When needed, files are passed around through shared folders. Usually there's one person in every group responsible for copying the "final" version of the files back to the production server. I find this absurd and even a bit dangerous.
How may I try to convince management that we should implement a VCS scheme in our department? I've never deployed a VCS myself but every other place I've worked at had one. I think I'll hit a "we've been OK until now, why bother" wall from the first step, coupled with the age of most of my co-workers that will feel this step is an unnecessary hurdle.
I know the basic advantages of VCS (traceability, granular backups, accountability etc). I'm looking to back my case with realistic cases and examples of real added value over the implementation costs, not just a "but-but-but, we must have a VCS you fools!" :-)
You don't necessarily need their permission.
Install svn on your machine, start using it, and then start convincing your fellow team members to use it too.
Then watch and see what happens.
Edits
The basic idea of this is that it's easier to show than to tell.
It's a great idea to support your ideas with a working implementation/solution.
Of course, if you succeed, and they want the system used department/company wide, you must be prepared to support the transition, know how the software is to be installed and used.
Going ahead and using something accepted in the industry is faster than having discussions on what system should be used.
There is a good change that this will get you noticed. You may also get your peers respect and support.
As suggested, the same approach can be made on other areas:
issue/bug tracking systems
quality tools
time tracking
continuous integration
a wiki for knowledge base, HOWTO's, guidelines, tutorials, presentations, screencasts
different IDEs and tools
build tools
automated deployment
various scripts that would save your team time
.. any item that will visibly add quality to your work, but doesn't (yet) disrupt existing methodologies and practices.
Joel Spolsky has an excellent article: Getting Things Done When You're Only a Grunt
Quote
Nobody on your team wants to use
source control? Create your own CVS
repository, on your own hard drive if
necessary. Even without cooperation,
you can check your code in
independently from everybody else's.
Then when they have problems that
source control can solve (someone
accidentally types rm * ~ instead of
rm *~), they'll come to you for help.
Eventually, people will realize that
they can have their own checkouts,
too.
Management? I will put bold the expressions and words you should use:
Your should display some examples how a VCS will prevent losing money to the company if some error/bugs or disaster happens. It will be faster to solve all problems, so maintaning the systens won't be so lazy and people become more productive.
You should also mention that implementing a VCS has no costs.
VCS will also give advantages for backup all the existing code. So, all the code will be safe.
My opinion on how to go about doing this, is that you should try to convince your fellow developers first. The way I see it, there are two ways this might go about:
You give the right arguments to the other developers (possibly only the head developers will suffice), they like the idea, and the suggest it to management. Management is easy to convince at that point, so everyone is happy.
You give the right arguments to management, who get all excited (great!) and mandate that version control has to be installed and used by everyone. Here's the thing: If at this point the other developers are not sold to the idea already, then (a) they might be hostile to an idea that management is forcing upon them, and (b) they might not like you for being the cause of it all.
So what are good arguments to convince fellow developers? As someone who uses subversion (which is the one I recommend in this case, by the way) even for his solo projects, here's a few advantages I can think of:
Using version control forces people to think of code modification in terms of a series of small, self-contained changes. This is an extremely beneficial way of working: where otherwise people would be inclined to make lots of changes all over the place, leaving the code in a mess, version control kinda forces them to change the code in bite-size, easy-to-swallow bits, keeping the code compiling at all times, easing the cost of integration with other modules, etc.
Version control makes it very easy to see what has changed in the code each time. This might sound trivial, but when you start modifying code it's easy to lose track after a while. But with VC it's all an "svn diff" (or equivalent) away, always.
Version control makes it very easy to see who has changed the code each time. So that, for example, when something breaks, you know who to blame. (It's not an accident that the subversion command which shows who last changed each line is called "svn blame".)
Version control makes it very easy to see why a piece of code was changed. Commit messages, if used properly, essentially provide continual documentation of the ongoing development process. Documentation that otherwise wouldn't be written.
Version control makes it very easy to track down regressions and see where they appeared. In the easy case, you just track down commit messages and spot the culprit. In the average case, you have to consult the diffs too. In the hard case, you have to do regression testing of previous versions using what amounts to binary search, which is still better than the no-VC case, where you simply have no clue.
This list is not exhaustive, of course, but these are the main benefits that come to mind right now. Obviously, as others have already mentioned, it's easier to show all this to your colleagues than to describe it to them, and setting it up for yourself first (but importing everyone's code, mind) sounds like a great idea.
As Joel points out on one of his articles, start using your own one man version control system and market its benefit on every opportunity you get. Show them the benefits of traceability, granular backups etc from your single instance. People will start realizing its benefits irrespective of their age.
I agree with the answer that are referring to the Joel Guerrilla article.
Install/Use some thing with a low overhead. Hg (Mercurial) is easy in a mixed eniroment and is good because you can bail out and use something else in an easy way.
You must share your things without making a fuzz about it. When someone needs your code, export it and use the "standard" corporate method (shared folder or whatever)
When you get code, always import it into a repos, if you think it is a new commit of a repos you already have, try to get it into that one.
Sooner or later you will have a code for several project and hopefully some commits on some repos. Then you can expose those with the mercurials webserver interface (hg serve -p XXXX).
When the times comes when someone don't know why something suddenly don't works as it should be and is trying to figure out why becase it was working last monday ... and you know that you have that code in a repos step up and ask if you can be of any assistance. Get the falty code, commit it into your repos and expose with hg serve. Look at it in the browser.
My point is that you must prove with real cases to your colleges that this stuff has a value.
If the haven't figured it out by themselves after some many years you have a mountain to climb but it can be done. You must be patience though. It could very well take a year to convert one man (old dog). If you have any younger coworkers try to do this together, the more code you can get hold on the better.
I would point out the hazards of not having one - lost code, developers over writing each other changes, ability to rollback problems, etc.
Also since Subversion and some others are free, point out there is no real cost to purchase, jsut the time to implement.
The biggest issue you will have as the new guy is that you will be seen as rockign the boat, if they had no issues to date they will be hard to convince. Perhaps start using it locally jsut for yourself and maybe they will like what they see and start to adopt it.
I would try small steps, maybe ask the others if they ever used one, point out the benefits, when an issue arises that a system would have prevented or aided in point it out delicately.
From a purely business perspective, and depending on the size and nature of your parent company an IT auditor may consider your lack of a VCS a finding (i.e. something that needs fixing). I believe you could improve your pitch to management by telling them that any CVS is a great way of showing that your department respects its resources and works in a structured way and efficient way, something auditors always like to see.
I don't know how your corporate culture works but I'd be careful about rolling out your own CVS since if it does see use it suddenly becomes your responsibility when things go wrong, even if you were not at fault. To cover your ass (and keep the aforementioned auditors even happier) I'd roll the system out with a full set of written procedures for its use and maintenance.
Finally while I myself am a big fan of initiative at any level of the enterprise don't expect people to remember to say thanks when they figure out how great it is. Some might, but for the most part you're doing this to make your own life easier and for your own karma.
Remember, there are plenty of version control systems that are absolutely free. And the amount of time spent installing and maintaining a version control system should be somewhere near 0 (they shouldn't require any maintenance). There isn't even a space penalty for most systems, as they can compress things internally.
You have listed some advantages, and there are others. But more importantly, I can't think of a single disadvantage.
I would also recommend starting with implementing VCS (Version Control System) for yourself first. I'd recommend using one of distributed VCS (Git, Mercurial, Bazaar) rather than centralized Subversion, because it would be easier to create central repository (or repositories) by cloning than moving your Subversion repository to central place. Distributed SCM can be also used in a smaller group to exchange ideas.
A few advantages of (modern) version control systems:
You can always revert (go back) to last working version of your code (provided that you follow some sane version control conventions, like at least tagging only tested code). With code shared via folders it might turn out that no one version works, backup copies were deleted to save space, and recovering code from backup is tedious / was never tested.
You can switch between working on some new feature (some experimental work), and working on urgent fix in currently deployed version (maintenace work) thanks to branches (and stash / shelve for uncommitted work).
If you follow good practices for version control (small and often commits, changes being about one single thing, writing good commit message describing change and whys of change) you would have much, much easier finding bugs, be it by bisecting history to find which change introduced bug, or by using version control system to look up who was responsible for given area of code (annotate / blame).
Start talking to the other developers about problems thay have had in the past as a way to get to know the system and how it evolved (sneaky, sneaky, sneaky, but hey this information will probably come in handy at some poitn even aside from the version control issue). You are bound to sooner or later find some wonderful examples of things that have already happened which would have been far less painful if you had version control. Use these examples when you present the idea to management.
I agree with the idea that you can probably start using your own version control and eventually will be able to help thm out of a fix, but I'd bet money they have been in some of those fixes already and if they already remember how painful the problme was before, it will help sell the new idea.
Look for another job.
Seriously.
There are way better jobs out there that don't require you to teach the existing staff.
Ones where you could go into work and just, y'know, work.
Also, keep in mind that 30 isn't far off. That's the age at which most people
stop suffering fools gladly.
Just a heads up.
EDIT
It's been suggested that quitting a bad job is for quitters.
Maybe so, but keep in mind that you're supposed to
put your employer to the Joel test before you accept the job, not after.

ClearCase advantages/disadvantages [closed]

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Because I'm currently struggling to learn IBM Rational ClearCase, I'd like to hear your professional opinion.
I'm particularly interested in advantages/disadvantages compared to other version-control-systems like Subversion or Git.
You can find a good comparison between ClearCase and Git in my SO answer:
"What are the basic ClearCase concepts every developer should know?", illustrating some major differences (and some shortcomings of ClearCase)
File-centric operations
The most single important shortcoming of ClearCase is its old "file-centric" approach (as opposed to "repository-centric" like in SVN or Git or Perforce...)
That means each checkout or check-in is done file per file. The atomicity of operation is at file levels.
Combine that with a very verbose protocol and a network with potentially several nodes between the developer workstation and the VOB server, and you can end up with a fairly slow and inefficient file server (which ClearCase is at its core).
File-per-file operations means: slow recursive operations (like recursive checkout or recursive "add to source control", even by clearfsimport).
A fast LAN is mandatory to mitigate the side-effects of that chatty protocol.
Centralized VCS
The other aspect to take into account is its centralized aspect (even though it can be "distributed" with its multi-site replicated VOB feature)
If the network does not allow access to the VOBs, the developers can:
still work within snapshot views (but with hijacked files only)
wait for the restoration of the network if they are using dynamic views
Expensive Distributed VCS option
You can have some distributed VCS feature by replicating a Vob.
But:
you need a special kind of license to access it.
that license is expensive and add to the cost of the regular license
any vob that uses the replicated vob (admin vob, admin pvob, ...) must be replicated as well (meaning some projects not directly concerned with a distributed development will still have to pay multi-site license...)
Old and not user-friendly GUI
the GUI is very old school and impractical (mid-90's MFC look, completely synchronous GUI, meaning you have to wait for a refresh before clicking elsewhere): when browsing baselines, you cannot quickly look for one in particular.
the GUI on Unix is not exactly the same than on Windows (the latest 7.1 version is better but not there yet)
the installation process is quite complicated (although the latest Installer Manager introduced by CC7.1 is now a coherent GUI on Windows or Unix and does simplify the procedure)
the only real rich application has only been developed for CCRC (the Remote Client)
UCM inconsistencies and in coherencies
As mentioned in "How to Leverage ClearCase’s features", dynamic views are great (a way to see data through the network without having to copy them to the disk), but the main feature remain UCM: it can be a real asset if you have big project with complex workflow.
Some shortcomings on that front:
the dependencies between components is not well managed for a depth superior to one (because of the bug of "parasite baseline")
UCM still has some in coherencies and inconsistencies as documented in CM Crossroads
Limited policies with Base ClearCase
Using ClearCase without using UCM means having to define a policy to:
create branch (otherwise anyone can create any branch, and you end up with a gazillon of them, with merge workflow nightmare)
put labels (otherwise you forget to label some files, or you put a label where you were not supposed to, or you "move" (gasp) a label from one version to another: at least UCM baselines cannot be moved)
define changeset. ChangeSets only exist with UCM activities. With Base ClearCase, you are reduced to clever "cleartool find" requests...
No application rights
ClearCase right management is entirely built on system rights.
That means you need to register your user to the correct system group, which is not always easy to do when you have to enter a ticket to your IT service in order for them to make the proper registration.
Add to that an heterogeneous environment (users on Windows, and server on Unix), and you need to register your user on Unix as well as Windows! (with the same login/group name). Unless you put some sort of LDAP correspondence between the two world (like Centrify)
No advanced API
only CLI is complete ("cleartool" is the ClearCase Command Line Interface), meaning that any script (in Perl or other language) consists in parsing the output of those cleartool commands)
ClearCase Automation Library (CAL) exists, but is quite limited
Java API exists, but only for web views for the CCRC client.
View Storages not easily centralized/backed up
The View storages are the equivalent of the ".svn" of SubVersion, exept there is only one "view storage" per view instead of many .svn in all the directories of a SubVersion workspace. That is good.
What is bad is that each operations within a view (a simple "ls", checkout, checking, ...) will trigger a network request to the view_server process that manages your view server.
2 options:
declare your view storage on your workstation: great for scalability, you can have as many view as you want without taxing the LAN: all communications are directly done on your workstation. BUT if that machine dies on you, you loose your views.
declare your view storage on a centralized server: that means all view_server process will be created there and that all operations on a view by any user will have to communicate with that server. It can be done if the infrastructure is "right" (special high-speed LAN, dedicated server, constant monitoring), but in practice, your LAN will not support this mode.
The first mode means: you have to backup yourself your work in progress (private files or checked-out files)
The second mode means: your workstation can be unavailable, you can just log on another a get back your views (execpt for the private files of a snapshot view)
Side discussion about dynamic views:
To add to the "dynamic view" aspect, it has one advantage (it's dynamic) and one shortcoming (it's dynamic).
Dynamic views are great for setting a simple environment to quickly share a small development between a small team: for a small development effort, a dynamic view can help 2 or 3 developers to constantly stay in touch one with another, seeing instantly when one's commit breaks something in the other views.
For more complex development effort, the artificial "isolation" provided by snapshot view is preferable (you see changes only when you refresh - or "update" - your snapshot view)
For real divergent development effort or course, a branch is still required to achieve true code isolation (merges will be required at some point, which ClearCase handles very well, albeit slowly, file-by-file)
The point is, you can use both, for the right reasons.
Note: by small team I do not mean "small project". ClearCase is best used for large project, but if you want to use dynamic views, you need to setup up "task branches in order to isolate a small development effort per branch: that way a "small team" (a subset of your large team) can work efficiently, sharing quickly its work between its members.
If you use dynamic views on a "main" branch where everyone is doing anything, then any check-in would "kill you" as it could introduced some "build breaks" unrelated with your current development effort.
That would then be a poor usage of dynamic views, and that would forget its other usages:
additional way of accessing data, in addition of snapshot views, meaning it is a great tool to just "see" the files (you can for example use a dynamic view to tweak its config spec until you see what you want and then copy those select rules into your usual snapshot view)
a side view to make merges: you work with your snapshot view, but for merges you can use your dynamic "sister-view" ("sister" as in "same config spec"), in order to avoid having a failed merge because of checked-out files (on which you would be currently working on your snapshot view), or because of a snapshot view not completely up-to-date. Once the merge is complete, you update your regular snapshot view and resume your work.
Developing directly in a dynamic view is not always the best option since all (non-checked-out) files are read over the network.
That means the dll or jar or exe needed by your IDE would be accessed over the network, which can slow down considerably the compilation process.
Possible solutions:
one snapshot view with all in it
a snapshot view with dll or jar or exe in it (files which do not changes every five minutes: one update per day), and dynamic view with only the sources visible.
The cost is a fairly obvious disadvantage. Not just the license cost, but also the cost of a ClearCase guru's salary. Almost every company I'm aware of that uses ClearCase seems to have at least one person whose only purpose is to tame the unruly beast.
The very fact that it's complicated enough to require a full-time nanny is also worrying.
An absolute nightmare of a system. It made me wish we could go back to VSS! (Never mind any modern source-control system like Subversion or Git!)
It's slooooow.
If you use dynamic views and the network goes down you cannot access your working copy of the source. You can do nothing but sit and wait for it to be fixed.
If you use snapshot views you seem to run into conflicts and "hijacked" files all the time, so the files in your working copy are never quite the same as in the source repository.
Whenever you try a large update or deliver operation it invariably FAILS for one reason or another, requiring your ClearCase guru to spend a few hour/days figuring it out. Oh yes, you must have a dedicated, full-time ClearCase guru!
When it fails you often cannot roll back the operation, either, so you're stuck with an operation in progress and the developers are blocked.
When you look past the pretty(?) icons, the GUI is very poor - right down to things like being unable to resize windows to see full file paths!
Their support staff are quite reluctant to fix anything. Their first response is always "this is by design" and "can you work around it?" If they do ultimately provide a fix (after much arguing) it will be the most basic possible fix to the most immediate problem.
Basically, it's slow, complicated and unreliable as hell. Oh, and did I mention it's ridiculously expensive? The only way they can possibly sell it is by talking to decision-makers who have never used the product and never will! I'm quite sure that no developer in the world would ever buy it.
Atomic commits and changesets are my biggest gripes against ClearCase. Let's say you check in five files as part of a bug fix or refactoring. Then it is discovered that something got messed up and you need to revert. Good luck finding which five files they are and what version each one needs to be on. But let's take a step back. You have just finished editing those five files, and it's time to commit. The first four go through just fine. That last one requires a massive merge. The other four files are already checked in. They don't wait for you to finish your necessary changes in the last file. I sure hope that no one updated or is using a dynamic view. A continuous integration build server is going to fail too.
Sometimes we make a whole new directory full of files that need to be checked in, but we don't want to check them in until they are done. It's early and everything is still volatile, so why check things in that you might delete very soon? OK, fine so far. Now it's time to check in. You add the newly created folder to source control. Well, ClearCase isn't recursive, so only that single folder is checked in. With SVN, that folder and everything below it is added, as you choose. The developer needs to remember to add everything, otherwise, a lot of files are going to be missing.
ClearCase owns the files and folders so you cannot modify anything unless you have checked it out first. The eclipse plugin takes away a lot of the nuisance here. I can't tell you how many times I opened a file in vi to make a quick change, only to find that I had forgotten to check it out first. Checkout isn't recursive either.
Updates can be painfully slow without changesets. When you update with a snapshot view, every file updates, not just the modified files. I worked on a project with 20,000+ files. I would remote in to my work machine, start the update, then drive to work; get coffee; go to my desk while it was finishing up. That might sound like an exaggeration, but it sadly isn't.
Dynamic views are terrible unless you are in a very small team. And if that's the case, why do you even have ClearCase? I have seen countless people's views getting hosed because someone checked in files that broke the views of everyone else. You should always update and merge any conflicts on your own view. That way, the changes only affect you. With a dynamic view, you cannot merge down before pushing back up; you just commit and hope.
I know cost probably isn't a big concern, but the developers who make the money for the company would enjoy spending the $50k-$100k (depending on ClearQuest license, which is a common addition) on either fun events or new equipment (chairs, monitors, etc.). IBM recommends having staff to keep ClearCase going. Why not re-purpose those people to generate revenue for the company, instead of making sure things don't crash and burn?
Some of the reasons that I have heard for not switching:
Learning will take time and money
Learning SVN or Mercurial should take no more than a day. Only ClearCase suggests having a certain ratio of admins to developers.
Migration will be painful
This is why tools exist: cc2svn
It's not as easy with Mercurial
Security
There are no known gaping holes in SVN AFAIK, and the development team is dedicated to fixing anything that is found quickly. The Department of Defense seems OK with SVN.
No real productivity gain afterwards
It takes forever trying to track down bugs without changesets. I love being able to roll back until I can't see the bug. You can't do that in ClearCase.
Multisite
WANdisco solves that problem. It's not free though.
The only thing that ClearCase does better than the rest is branching individual files, while keeping the others on the same track as another branch.
Everything I have done in Clearcase always seems hard. Whereas, I've never had that impression with other systems(except maybe CVS on occasion).
I've used SVN, CVS, Clearcase, and Mercurial.
My experience with ClearCase was a disaster, and I will second Don's statement that it requires a resident expert-- unfortunately we had more than one. I had experience with CVS and other version control systems, I was familiar with the concepts, but I found the ClearCase documentation incomprehensible and had to ask for help several times; different experts gave me conflicting advice to the point where we actually broke cd. That is, after I issued a ClearCase command in a UNIX shell, the "cd" command failed with an error message.
The basic task of a version control system is really pretty simple. Honestly, I think that half a dozen commands should suffice, using a file scheme that plays well with others. To me ClearCase looks like the result of a marketing exec deliberately complicating the hell out of things to make the product look sophisticated and powerful. I've heard that it can be configured to behave in a simple, safe, reliable way, but again that requires the services of an expert-- out of the box it's like a motorized swiss army knife.
Everything I've experienced related in any capacity to ClearCase is inefficient, ugly, overly complex, slow, confusing, expensive and inconvenient.
It seems to attract managers and engineers that JUST HAVE GOT IT ALL WRONG.
Damn, IBM and Rational must have amazing sales guys to sell such a crappy product.
We are just migrating off CC onto Git for many of the reasons given here. I would like to add one reason to stay away from CC or any other commercial source control system.
Your vital business data is hostage to ClearCase. You can't get it out.
Your vital business data is the code, its version history and all metadata such as commit comments, who checked in and when.
All software will have a limited useful life. You should always ask yourself when you introduce a new system that swallows important business data, whether it is code, bugs, customer data or what not: How do I get my data out again? If you can't answer that question, you should not introduce that system.
When we migrated out we lost most of our history and all of our metadata. Essentially we only have history corresponding to released versions, but information about what changes were done in response to what customer requests is lost (we have that data in the customer support and bug ticket system, so it is not completely lost, but the coupling to the source code is gone).
This will be somewhere between a nuisance and a problem for us on short to medium term. In a couple of years time, it is not important anymore, but perhaps for 1-3 years it will matter.
(There are commercial tools to migrate CC to other SCM, but they were not deemed adequate to our needs, and I doubt it would have been feasible. The minimal export we did took long enough.)
The lesson learnt is: Never entrust vital business data to proprietary systems.
No atomic commits
Once you checked in files it is very hard to revert to a certain state, because atomic commits aren’t supported. When checking in multiple files, each file gets a new revision (similar to CVS) and not the check-in itself. I think this is a crucial feature, because you hardly want revert single files but complete commit actions (which should map tasks). With ClearCase you can only revert to certain states by using Labels. In practice using ClearCase Labels for each check-in is overkill and thus not done.
Crappy user interface
The GUI of ClearCase Explorer is just a big joke. Horrible in usability and ugly looking. Different and often necessary functions aren’t provided (e.g. recursively checking in worked on artifacts). Command line tool cleartool used with cygwin is much better, but still some things aren’t available like recursively adding new files/folders to source control. I have to laugh my head off if I read a 50 lines of code long script to workaround this.
High administration efforts
Administrating ClearCase beast is far from obvious or lightweight (in difference to other scm-systems like CVS, subversion or Git). Expect to put quite a few dedicated ClearCase experts to just keep it running.
Horrible performance
Nothing is worse as making your developers wait while interfacing with SCM-tool, it is like driving with hand brakes enabled. It slows down your brain and also your work. Getting fresh new files to your snapshot view takes around 30 minutes for 10K artifacts. An update (no artifacts were changed) for the same amount takes roughly 5 minutes. When experimenting a lot and jumping between different up-to-date views means a lot of waiting. It gets even worse, when you’re working on files and you want to check-in or update them. Check-out, check-in and adding to source control cycles take around 10-15 seconds which is obviously a nightmare. It gets very annoying when you’re refactoring renaming/moving types or methods (many files can be affected).
Lack of support of distributed development
Today software development is often a distributed thing (developers are spread around the world working on the same product/project). ClearCase definetely isn’t suitable for this, because it is badly suited for offline work. Doing a check-out (action before you can edit a file/folder) requires that you are network connected. Here you could use the hijack option but this is rather a workaround as a feature (you basically just unlock the file on the filesystem). If your development sites are far away from your ClearCase server the check-in/check-out latency can even increase so dramatically that it is not usable at all. There are workarounds for that like using ClearCase Multisite (scm DB replica technology), but you have to pay extra for it and is not trivial to adminstrate.
Git as alternative
Though being a big fan+supporter of Open Source I am still willing to pay money for good software. But looking at IBM-monster ClearCase I wouldn’t invest my money here, it has all these discussed shortcomings, and further more IBM doesn’t seem to invest money to improve their product significantly. Recently I had a look a Git scm which looks very good, especially for its branching+merging features, where ClearCase has its major strengths.
This information taken from http://www.aldana-online.de/2009/03/19/reasons-why-you-should-stay-away-from-clearcase/
Possibly the worst software ever made. I will not work for any firm that uses rational anything. Aside from CC completely crashing and restarting my workstation frequently on dynamic builds. What happens when you are pushing something to source control and CC does what it does best, crash? Is your code then put in lost+found, backed up somewhere maybe? No, it is gone forever. So if you are ever in the god-awful situation of using this giant piece of expensive software, keep duplicates of everything. Good job Rational / IBM. Way to capture the most important part of source control, reliability. Die slow.
Downsides of ClearCase - an addition to the most in-depth post here.
The merge tool is not worthwhile. It barely helps you, remembers no decisions you made, its just a glorified diff.
The merge tool has to check out directories to even CHECK if they need a merge. Its a bit insane.
I use BitKeeper at work (let's assume Git), and merging two repositories even if there are conflicts is so trivial and user friendly even with command line, while ClearCase having tons of GUI tools is a long and laborious process which is also extremely error prone.
All GUI tools require a ton of latency. Even seeing what can be done on a file requires a high speed connection. So right-clicking in the ClearCase tool on a file working from home could take a minute or two having high speed internet because of the extreme amount of networking requirements.
Someone can completely mess up the repository or check-ins if they make their view spec different than the team. Which is quite insane that nobody can just check out some branch; they need the appropriate view spec which will incidentally give them the right stuff. The whole concept can be nice and flexible but 99% of the time it just causes lots of pain. Did I mention you can't email your spec via Microsoft Outlook since CC tools don't accept UTF-8 so you can't copy-paste it?
I have absolutely nothing nice to say about CC. I used it for 2 years at 2 companies and dropped it in a heartbeat feeling happy the entire time. It is also impossible to just experiment with at home with your own projects, so you will still learn SVN or Git at home, and be forced to go through ClearCase pains at work. Nobody I know has ever used CC voluntarily. They only use it because some manager at work decided CC is the path to salvation and forced everyone to migrate to it. In fact my last company migrated from CVS to ClearCase, and after one year from ClearCase to SVN. It was that hated.
ClearCase is not just one thing that makes you say no. It's like living in a house infested with ants. Each ant is just a minor inconvenience at best, but the infestation will drive you mad.
I'm trying to consolidate a few comments into an actual post here. I'm not really here to persuade you that one is better than the other, except by way of making a few points:
If you're comparing git and ClearCase, I respectfully submit that you need to better define your needs - if you are considering ClearCase for a "good" reason, the git probably isn't even in the equation - it's far too new to trust for enterprise-level source control, imo.
ClearCase introduces a lot of concepts into the version control space that other systems don't have, so it can be pretty daunting and confusing. Especially if the only experience you have is reading the documentation, as appears to be the case for a few people here.
ClearCase is definitely not well suited to huge code bases supported by developers who are not on a LAN with a VOB server. You can have many replicated (multi-site) VOB servers to get them close to remote developers, but this isn't necessarily practical if those remote sites are just a single developer.
Do you want file versioning or repository versioning? This is a pretty important question, and one that will necessarily filter out an entire set of tools, making your job easier. Repository versioning has a lot of advantages (and it's not "new", like some posters claimed - commercial tools like Perforce have been around for more than a dozen years, and there may have been tools that did repository versioning even before Perforce), but it isn't a panacea.
With a sufficiently large installation of any source control system, you're going to need help. When considering tools, you need to consider how easy it will be to find people to help you (either job applicants who have experience, or consultants who will be there at a moments' notice to address any issues). There's no such thing as a maintenance-free SCM system, and assuming you have one will get you into more trouble than picking one that requires "too much" administration.
Don't pay too much attention to people who talk about how bad "dynamic views" are - bad SCM policies are bad, regardless of the tool you're using. Your configuration management policies and practices have to be separate from your choice of tool - no tool will stop people from smashing all over your codebase if you don't define sensible branching and merging policies. If someone suggests that having developers directly commit onto /main is ever a sensible idea, you might want to walk away from that conversation.
ClearCase is a fine tool, but it is a complicated tool. There is no getting around this - it does not have an "easy install" mode. :-) From a technical standpoint, there's nothing that git or SVN can do that ClearCase cannot (although often the terminology is different, since Open Source projects tend to just invent new taxonomy where there already existed one), but some things are definitely easier/harder for a given system, depending on their design. ClearCase "snapshot" views are basically the same thing you would have if you checked out a repository from SVN or CVS - it's a local copy of the source code on your machine, with pointers back into the central server for tools to query version history, etc. You can work with these views without any network connection to the ClearCase server at all once they have been created, and you can "recycle" them to avoid downloading your entire repository again when you want to move to work on another branch, for example. "Dynamic Views" are basically a ClearCase invention, and the standard operating mode for a LAN. They appear the same as checking out an SVN repository, but they don't actually copy any files until you make changes. In this way the view is available immediately, but it obviously cannot be worked with if the main clearcase server is unavailable, and is unpleasant to work with over a high-latency connection. They also have the convenience of being able to be mounted as a network drive on any machine with access to the server on which they were created, so if your windows workstation dies, you can just log onto another one, mount your view, and get back to work, since all the files are stored either in the VOB server (for files you haven't modified on this branch), or the view_server (for files you have created or modified just in this view).
Also, and this deserves its' own paragraph....clearmerge is nearly worth the price of admission alone. It's hands down the best merge tool that I've ever used in my life. I firmly believe a lot of bad practice in SCM has developed because of a lack of high-quality merge tools, so CVS users never learned to use branches properly and this fear of branching has propagated to the current day for no particularly good reason.
Ok, all that being said, if you're looking for reasons not to use ClearCase, they're not hard to find, although I think that's the wrong way to go about it. Really you should need to come up with good reasons TO use ClearCase, not reasons for NOT using ClearCase. You should come into any SCM situation assuming that ClearCase is too much tool or too complicated a tool for the job, and then see if you have some situation that encourages you to use it anyhow. Having IBM or Rational logos is not a good reason.. :-)
I would not even consider ClearCase unless you could say yes to all the following statements:
You do now, or will eventually have, more than 50 developers working on the same codebase.
Most of those developers are centrally located, or have high-throughput low-latency connections to a central location.
You have a set of SCM policies and can identify how to use ClearCase to enforce those policies (really you should consider this for any tool)
Money really is no object
My experience is mostly limited by CC, CVS and SVN. In principle, CC is technologically capable, enterprise ready and comparable by features with any modern VCS. But it has several flaws that make it unusable in any people-oriented environment. For process oriented environments it is probably more appropriate, though I doubt that such environments are appropriate by themselves. Maybe, in military, cosmic or medical software, I don't know. Anyway, I believe that even for these domains there are appropriate and still more friendly tools.
Beside being technically capable VCS, CC has several distinctive advantages:
Dynamic views
Nice version tree
Triggers
Good merge versioning, including renames
In my opinion, their use is limited excepting last one; and they don't compensate flaws. Dynamic view nice in theory, but not always available in practice. Version tree has much less use in other VCS, while necessary in CC because of proliferation of branches (see 6). Triggers, as I know, very detailed and capable, but I think that for most practical tasks SVN hooks are good enough. And now about disadvantages that mostly concerns usability:
CC totally fails in sense of usability for main user group: for developers. And that is the main reason why I think that it should never be used in any environment, be it enterprise or not. Even if it were free, it would nevertheless suck your company's money by wasting time of your developers and frustrating them. This point is composed from:
"Check out-Check In" with strict locking approach - it is counter-productive, refactoring unfriendly, and dangerous in repository organizations with single development branch for multiple developers. Meanwhile, the advantages of strict locking are negligible.
Poor performance and high load
It effectively cannot be used remotely without multi-site (due to 2). Multisite is expensive too. ClearCase Remote client is very limited. It don't even have cleartool (before version 7.1), leaving alone dynamic views.
It can hardly be used offline. Dynamic views are just not work. Snapshot views are effectively read only, because you cannot check out without access to repository (see 1). Hijack is poor option which in fact means that CC gives up any responsibility for hijacked file. And CC cannot show you difference with previous revision when offline. SVN is able to show difference with previous revision even being offline.
Overly complicated model, especially with UCM: VOBs, PVOBs, Projects, streams, branches, views, deliver, update, load, restore, rebase, merge, baseline, check in, check out. I think that half of this concepts are just superfluous and doesn't add value, while increasing both technical and conceptual complexity. Few developers understand even basic stuff about CC.
Proliferation of branches. For example, repository often organized with stream per developer (due to 1). It just has no sense in SVN or most other VCSs.
No repository wide revisions. Well, there are such revisions as understand, they called baselines. But when I see some file revision and want to get repository snapshot at the moment of that file revision, I will get some problems. I will need to do black magic with config spec to create a snapshot view, or find somehow through dynamic view if it is available.
Crappy user GUI. Version tree, even being nice, has mediocre usability. Merge tool is just a pity. Other "features": not resizeable windows, absence of incremental search in some places, mouse-centric interface, look and feel in 1995 style, strange work flow distributed between Client and Project Explorer etc.
CC provokes rare and vast check ins. You all know, that check ins must be small and frequent. But developers usually refrains from additional interactions with CC, hijack files and work in local VCS or even without VCS at all (which is more often, unfortunately). And then, after two weeks of development they begin commit comlex feature that adds 20 files and affects another 20 files. It lasts for a day or two, because they hijacked files and now need to perform manual merge with all new changes from repo and resolve all conflicts and discrepancies. During that process, code lies not compilable, because several files successfully got checked in and others do not. And after that it still lies not compilable because they forgot to add another 2 files to CC.
It is very expensive
It is very complex in terms of infrastructure and requires dedicated administrators
ClearCase seems extremely powerful, from the outside. But really, it's just that the number of commands and options you need to use for basic workflow is so high that these get hidden behind a few aliases or scripts, and you end up with something less powerful than CVS, with the usability of Visual Source Safe. And any time you want to do something a little more complicated than your scripts allow, you get a sick feeling in your stomach.
Compare this with Git, which seems complicated from the outside, but after a week working with it you feel completely in control. The repository model is simple to understand, and incredibly powerful. Because it's easy to get at the nuts and bolts, it's actually enjoyable to dig below the surface of your daily workflow.
For example, figuring out a trivial task such as how to just view a non-HEAD version of a file in a snapshot view took me a couple of hours and what I ended up with was a complete hack. Not the enjoyable sort of hack either.
But in Git, figuring out a seemingly complicated task such as how to interactively commit only some changes, (and leave the rest for later) was great fun, and all the time I have the feeling that the VCS is allowing me to organise code and history in a way that suits me, rather than history being an accident of how we used the VCS. "Git means never having to say 'you should have'".
At my work, I use Git for all sorts of lightweight tasks, even within ClearCase. For instance, I do TDD, and I commit to Git whenever a bunch of tests pass and I'm about to refactor. When the task's eventually done, I check in to ClearCase, and Git helps me review exactly what I'm changing. Just try to get ClearCase to produce a diff across a couple of files - it can't! Use Google to find out the various hacks people have tried to work around this. This is something version control should do out of the box, and it should be easy! CVS has had this for decades!
Nightmare to administer in secure environments
Outdated technology
Non-intuitive GUI
Expensive
Resource monster
Sellout to Microsoft
In my opinion? Only reason to have it? If you are religiously following RUP.
The support is terrible. We've had tickets open for years. Our eclipse guru actually fixed a bug in their eclipse plugin locally in about 30 minutes by disassembling the java file. But the ticket still hasn't got past level one support. Every so often they either try to sneakily close it or ping it back to us 'to try on the latest version' (even though we sent them a reproduction recipe which they could try for themselves.).
Do not touch with a barge pole.
Performance.
ClearCase is powerful, stable (IF properly maintained and supervised) but it's slow.
Geological sometimes.
Dynamic views views lead to horrible build times, snapshot views can take ages to update (lunch break for large projects) or checkout (go home for the day).
Clearcase is so annoying it actually drives people to write poetry about it:
http://digital-compulsion.blogspot.com/2007/01/poetic-pathetic-version-control.html
http://grahamis.com/blog/2007/01/24/if-it-was-free-no-one-would-download-it/
The developers will spend 1/2 their time figuring out clearcase before doing any work and once they've figured it out they'll install git locally and only push to the clearcase repo as needed.
You'll have to employ a dedicated Clearcase admin.
I would suggest SVN for toolset and Git for scaling/workflow. I'd also suggest avoiding CC where possible. (Not counting money, the fact it is such a pain to use that is requires a full time admin is a total joke)
I recently had to wrangle with a similar situation. Maybe you can learn from my story.
The team I was newly assigned to was using a heavyweight tool in an convoluted, error-prone manner. I first attempted to sell them on my tools and processes of choice. This attempt failed miserably. I was flabbergasted that they would pick such a burdensome environment over one that was both easier and more effective. Turns out that they wanted to be disciplined, and using a painful process felt disciplined to them. It sounds wierd, but it's true. They had a lot of other misconceptions too. After I figured out what they were after, we actually stuck with the same tool suite (Serena), but massively changed how it was configured.
My advice to you is to figure out what matters to your team. Ripping on ClearCase won't get you anywhere unless you speak to their interests. Also, find out why they don't want to use alternatives. Basically do a little requirements gathering and fit your tool choices to your needs. Depending on your options, who knows, Clear Case may end up being the best option after all.
I'm not totally against ClearCase ( it does have it's advantages ), but to list out the disadvantages:
License Limitations - I can't easily work from home, because I don't have access to the license server. Even with a snapshot view on my laptop I have to play tricks because I can't get a license. There is a special remote client, but adds tons of its own limitations to the mix
License Limitations again - Only so many seats to go around, and then no one can use it.
Unix tools out of date - ClearCase seems to run best on Unix systems, but the GUI tools suck there. Windows/Unix integration of ClearCase introduces all sorts of its own pains.
The biggest downfall for me is both the performance (especially if your VOB is multisite or offsite), and potentially lengthy downtimes.
If you're like me and work in a relatively small office as part of a large company (with no onsite IT), Clearcase servers going down can cost you the better part of a workday in non-productivity as well as getting the right people to get it fixed.
Bottom line, use it only if you really need it for what you are doing and make sure you have a beefy IT budget to maintain it.
ClearCase is perfectly usable if your willing to also use another version control system on top of it! personally I find using mercurial ontop of CC to work quite well.
no atomic checkins
As of the new version of version 7.1 CC provides atomic checkin as functionality IF you like that. Personally I would really not want it but apparently some people see that as "an essential feature". I NEVER would want one big bulk in one go as a sort of massive version. Then again... if you want it just turn it on.
so... no longer an argument.
We used UCM ClearCase integrated with ClearQuest (DR Tracking/change request system) for the last 4 years with more than 50 developers. We have over 50 UCM projects over thousand of streams that handled over 35K DRs and change requests. During this period we have officially made over 600 integration deliveries and while having up to 6 concurrent development and release efforts.
I am the main CM/ClearCase guy with a backup who is able to perform the regular delivery/merge and integration builds. The network and servers are supported by the IT team. All I can say is we have had virtually no problems coming from the CM side of this huge development effort and were never a show stopper. Our developers where trained with just the basic stuff and a simple steps were given to them whenever a new project (branch) was created at the request from the project management.
Too many developer complained about ClearCase because they lack the proper CM/IT/ClearCase/Process/Management support. Developers should focus on development not SCM or be a tool specialist. For a large software development, at least 5-7% of the budget should be spent on CM and tool support.
Running a JDK from a VOB in Linux.
Try it, you need to play with the LD_PRELOAD variable (I know!)
the point of "it needs a dedicated person" and "it is complicated" etc....
The core issue here with finding this a problem is that you have to define if you want to have configuration management performed in your organization (which is NOT version management). Configuration Management is like Project Management: even without a tool you still can do project managment and without a tool you can do Configuration Management. Lots of people have a hard time understanding this and lots of people think Configuration Management is equal to a tool which versions sources of software or something...... (therefore comparisons with subversions or other VERSION management systems)
ClearCase is a solution that is build for usage in a Configuration Management environment ERGO: there is a configuration manager (just like "there is a project manager").
So... if in your perception that dedicated person is there to manage a tool I think there is something very wrong. In my perception there is a dedicated person who does configuration management who from an end-user perpective only shows up when there is a problem with the tool but regards this as only 1% of his job.
So what you need to do (like in any other software project) go back to your requirements and put a list of requirements together on what your organisation wants with configuration management. AND YES like in any other software project you will have users (like e.g. developers) who totally not agree with other users (like e.g. management) on certain requirements. There lies the key imho on some reactions I read here.
And IMHO if you have the organization list of requirements AND a configuration manager in the mix.... the choice is pretty clear (see also the forum on www.cmcrossroads.com)
ClearCase is not a tool only for end-users entering their sources under version control like subversion or git. That is only 1% of why a configuration manager really wants a mature configuration management tool.
And... I think the choice of a CM system should never lay with developers equal to choosing the right project management tool or the right CRM system. Developers are end-users of a certain part of the functionality of the tool.
I will be maybe alone here, but ClearCase is not that bad as everyone says. It can handle huge repositeories. Dynamic view are pretty cool and powerful feature too. It is reliable, can be customized by adding triggers and constraints on a pef file basis, permissions, etc.
Unfortunatelly, it comes with a price, big price. It is costly, and to operate properly needs to be properly configured and maintained by dedicated IT team. It makes it really good for BigCo, but not so wise choice for SmallFirm.
I'm a big fan of DVCS and git, but can understand why would BigCo choose ClearCase over SVN and Git. What I can't understand why would anyone choose SVN over Git ;>
Dynamic Views. Must admire a fully functional translucent file system.
One big benefit is that the Intellectual Property is always in the corporate network. A laptop can be lost/stolen and no source code in jeopardy.
Another is the instant access to source code and changed files, no time is ever spent downloading anything.
It serves well for the purpose it has.

Strategies for Developing Multiple Products from One Codebase

I'm working on a project that will (soon) be branched into multiple different versions (Trial, Professional, Enterprise, etc).
I've been using Subversion since it was first released (and CVS before that), so I'm comfortable with the abstract notion of branches and tags. But in all my development experience, I've only ever really worked on trunk code. In a few rare cases, some other developer (who owned the repository) asked me to commit changes to a certain branch and I just did whatever he asked me to do. I consider "merging" a bizarre black art, and I've only ever attempted it under careful supervision.
But in this case, I'm responsible for the repository, and this kind of thing is totally new to me.
The vast majority of the code will be shared between all products, so I assume that code will always reside in trunk. I also assume I'll have a branch for each version, with tags for release builds of each product.
But beyond that, I don't know much, and I'm sure there are a thousand and one different ways to screw it up. If possible, I'd like to avoid screwing it up.
For example, let's say I want to develop a new feature, for the pro and enterprise versions, but I want to exclude that feature from the demo version. How would I accomplish that?
In my day-to-day development, I also assume I need to switch my development snapshot from branch to branch (or back to trunk) as I work. What's the best way to do that, in a way that minimizes confusion?
What other strategies, guidelines, and tips do you guys suggest?
UPDATE:
Well, all right then.
Looks like branching is not the right strategy at all. So I've changed the title of the question to remove the "branching" focus, and I'm broadening the question.
I suppose some of my other options are:
1) I could always distribute the full version of the software, with all features, and use the license to selectively enable and disable features based on authorization in the license. If I took this route, I can imagine a rat's nest of if/else blocks calling into a singleton "license manager" object of some sort. What's the best way of avoiding code-spaghettiism in a case like this?
2) I could use dependency injection. But generally, I hate it (since it moves logic from the source code into configuration files, which make the project more difficult to grok). And even then, I'm still distributing the full app and selecting features at runtime. If possible, I'd rather not distribute the enterprise version binaries to demo users.
3) If my platform supported conditional compilation, I could use #IFDEF blocks and build flags to selectively include features. That'd work well for big, chunky features like whole GUI panels. But what about for smaller, cross-cutting concerts...like logging or statistical tracking, for example?
4) I'm using ANT to build. Is there something like build-time dependency injection for ANT?
A most interesting question. I like the idea of distributing everything and then using a license key to enable and disable certain features. You have a valid concern about it being a lot of work to go through the code and continue to check if the user is licensed for a certain feature. It sounds a lot like you're working in java so what I would suggest is that you look into using an aspect weaver to insert the code for license checking at build time. There is still a going to be one object into which all calls for license checking goes but it isn't as bad of a practice if you're using an aspect, I would say that it is good practice.
For the most part you only need to read if something is licensed and you'll have a smallish number of components so the table could be kept in memory at all times and because it is just reads you shouldn't have too much trouble with threading.
As an alternative you could distribute a number of jars, one for each component which is licensed and only allow loading the classes which are licensed. You would have to tie into the class loader to achieve this.
Do you want to do this via Subversion ? I would use Subversion to maintain different releases (a branch per release e.g. v1.0, v2.0 etc.) but I would look at building different editions (trial/pro etc.) from the same codebase.
That way you're simply enabling or disabling various features via a build and you're not having to worry about synchronising different branches. If you use Subversion to manage different releases and different versions, I can see an explosion of branches/tags in the near future.
For switching, you can simply maintain a checked-out codebase, and use svn switch to checkout differing versions. It's a lot less time-consuming than performing new checkouts for each switch.
You are right not to jump on the branching and merging cart so fast. It's a PITA.
The only reason I would want to branch a subversion repository is if I want to share my code with another developer. For example, if you work on a feature together and it is not done yet, you should use a branch to communicate. Otherwise, I would stay on trunk as much as possible.
I second the recommendation of Brian to differentiate the releases on build and not on the code base.

version control practice

In my current job the supervisor's practice is to only check in production ready code. Most recently the project I was on involved work by 3 different developers with some file overlap. This meant manually integrating changes despite the fact that some changes took a day and then it was done. I wanted to see if this was a common practice and get suggestions on how to change this practice with the knowledge that many times my opinion means little in the grand scheme of things.
You can use various ways to handle this situation, depending on your source control system.
Private branches: Allow you to check in and work on code while you go, merging back and forth at appropriate times.
Shelvesets/pacakaged changesets: Allow you to store changesets and send them around for review - ensuring they're production ready before check in.
As to whether this is an appropriate way to work, we don't allow check-in to main branches without prior review. To pass review your code must pass various automated tools, and then must be acceptable to your peer reviewer. For some definitions of "production ready" - this is it. Therefore, we do something like what you do. However, we use private branches to ensure that check-ins can still be made while this is in progress, and that other check-ins don't have to interfere.
If production ready means tested in an integration environment, then it sounds like you may need staging branches or something similar.
Code that is checked in should be unit tested, but, to me, "production ready" implies that it's gone through integration and system testing. You can't do that until a code freeze, so I don't see how you can do that before every check in.
Start by switching away from VSS to something more reliable & feature-rich. See How to convince a company to switch their Source Control
Then apply known-good practices:
Check in often
Pick up others' changes often, to simplify merging
Use fast unit tests to make sure each change meets a minimum bar
Require that that the checked-in code always builds, and always passes tests.
Now you won't be "production ready" at this point: you will still need a couple weeks to test & fix before you can deploy. Getting that time down is awesome for you, and awesome for your customer, so invest in:
High quality automated acceptance tests.
wouldn't it be a good idea to have a testing branch of the repo that can have the non "production ready code" checked in after the changes are done and tested?
the main trunk should never have code checked in that breaks the build and doesn't pass unit tests, but branches don't have to have all those restrictions in place.
I would personally not approve of this because sometimes that's the best way to catch problem code with less experienced developers (by seeing it as they are working on it) and when you "check in early and often" you can rollback to earlier changes you made (as you were developing) if you decide that some changes you made earlier was actually a better idea.
I think it may be the version control we user, VSS in combination with a lack of time to learn the branching. I really like the idea of nightly check ins to help with development and avoid 'Going Dark'. I can see him being resistant to the trunks but perhaps building a development SS and when the code is production ready move it to production SS.
From the practices I have seen the term production quality is used as a 'frightener' to ensure that people are scared of breaking top of tree, not a bad thing to be honest because top of tree should always work if possible.
I would say that best practice is that you should only be merging distinct (i.e. seperate) functional components on the top of tree. If you have a significant overlap on deltas to the same source files I think this 'might' indicate that somewhere along the line the project management has broken down, and that those developers should have merged their changes to seperate integration branch before going in to the main line sources. An individual developer saying that they unit tested their stuff is irrelevant, because the thing they tested has changed!
Trying to solve integration problems on your main line codeline will inevitably stall other unrelated submissions.
Assuming that you are working in a centralized version control system (such as Subversion), and assuming that you have a concept of "the trunk" (where the latest well-working code lives):
If you work on new features in "features branches"/"experimental branches", then it's OK to commit code which is far from finished. (When the feature is done, you commit the well-behaving result into the "trunk".)
But you will not win a popularity contest if committing non-compiling/obviously non-working code into the "trunk" or a "release branch".
The Pragmatic Programmers have a book called Pragmatic Version Control using Subversion which includes a section with advice about branches.
Check in early and check in often for two main reasons -
1 - it might make it easier to integrate code
2 - in case your computer explodes your weeks of work isn't gone
An approach I particularly like is to have different life cycle versions in the depot. That is,for example, have a dev version of the code that is where the developers check in code that is in being worked on; then you could have a beta version, where you could add beta fixes to your code; and then a production version.
There is obvious overhead in this approach, such as the fact that you will have a larger workspace on you local machine, the fact that you will need need to have a migration process into place to move code from one stage to the next (which means a code freeze when doing the integration testing that goes with the migration), and that depending on the complexity of the project(s) you might need to have tools that change settings, environment variables, registry entries, etc.
All of this is a pain to set up, but you only do it once, and once you have it all in place, makes working on different stages of the code a breeze.
#bpapa
Nightly backups of work folders to servers will prevent losing more than a days work.
#tonyo
Let's see the requirement documents were completed the day after we finished coding. Does that tell you about our project management?
We are a small shop so while you would think change is easy there are some here that are unbending to the old ways.