# Version Control System Comparison

This is a comparison of version-control systems. It is split into several categories and sub-categories under which the systems are checked.

Timestamp: `$Id: scm-comparison.xml 313 2008-07-12 07:25:40Z shlomif $`

## Repository Operations

### Atomic Commits

Support for atomic commits means that if an operation on the repository is interrupted in the middle, the repository will not be left in an inconsistent state. Are the check-in operations atomic, or can interrupting an operation leave the repository in an intermediate state?

CVS | No. CVS commits are not atomic.
AccuRev | Yes. Commits are atomic
Aegis | Commits are atomic.
Arch | Yes. Commits are atomic.
Bazaar | Yes. Commits are atomic.
BitKeeper | Yes (but need to verify)
ClearCase | Yes. Commits (checkins) are atomic.
CM+ | Yes. Commits are atomic.
CMSynergy | Yes. Commits are atomic.
Co-Op | Yes. Commits are atomic.
Darcs | Yes. Commits are atomic.
Git | Yes. Commits are atomic.
LibreSource Synchronizer | Yes. Commits and updates are atomic.
Mercurial | Yes.
Monotone | Yes.
OpenCM | Yes. Commits are atomic.
Perforce | Yes. Commits are atomic.
PureCM | Yes. Commits are atomic.
SourceAnywhere | Yes. Commits are atomic.
Subversion | Commits are atomic.
Superversion | Commits are atomic.
svk | Commits are atomic.
Team Foundation Server | Yes. Commits are atomic.
Vesta | Yes. Commits are atomic.
Visual SourceSafe | No. VSS commits are not atomic.

### Files and Directories Moves or Renames

Does the system support moving a file or directory to a different location while still retaining the history of the file? Note: also see the next section about intelligent merging of renamed paths.

CVS | No. Renames are not supported and a manual one may break history in two.
AccuRev | Yes. Renames of both files and directories are supported. Supports controlling of symbolic links as well.
Aegis | Yes. Renames are supported.
Arch | Yes. Renames are supported.
Bazaar | Yes. Renames are supported for files and directories.
BitKeeper | Yes. Renames are supported.
ClearCase | Yes. Directories are first-class controlled entities in Clearcase. Even supports controlling of symbolic/hard links.
CM+ | Yes. Both moves and renames are supported, while maintaining history.
CMSynergy | Yes. Renames are supported.
Co-Op | Renames of files are supported. Renaming a directory requires creating a new one, moving the files and deleting the old one. Moved file histories are preserved.
Darcs | Yes. Renames are supported.
Git | Renames are supported for most practical purposes. Git even detects renames when a file has been changed afterward the rename. However, due to a peculiar repository structure, renames are not recorded explicitly, and Git has to deduce them (which works well in practice).
LibreSource Synchronizer | Yes. Renames and move are supported but the working copy needs to be up-to-date before doing a rename/move operation. This operation will be committed directly.
Mercurial | Yes. Renames are supported.
Monotone | Yes. Renames are supported.
OpenCM | Yes. Renames are supported
Perforce | Not directly (you copy and then delete but it manages to keep track of the branch)
PureCM | Yes. File renames are directly supported. File and folder moves require creating a new one and deleting the old one. Moved file histories are preserved.
SourceAnywhere | Yes. Both moves and renames are supported, while maintaining history.
Subversion | Yes. Renames are supported.
Superversion | No. Renames are not supported.
svk | Yes. Renames are supported.
Team Foundation Server | Yes. Both moves and renames are supported, while maintaining history.
Vesta | Yes. The unit of checkout/checkin is a directory tree. Files and directories can be added, deleted, and renamed between versions.
Visual SourceSafe | Affects the whole history, it's like renaming a file in the CVS repository. There is a kludgy workaround using "share-rename,move,delete" that gets what you want.

### Intelligent Merging after Moves or Renames

If the system keeps tracks of renames, does it support intelligent merging of the files in the history after the rename? (For example, changing a file in a renamed directory, and trying to merge it).

CVS | Renames are not supported at all, much less intelligent ones.
AccuRev | Unknown. FILL IN.
Aegis | Unknown. FILL IN.
Arch | Yes. Renames can be merged intelligently.
Bazaar | Yes. Renames are intelligent.
BitKeeper | Probably Yes.
ClearCase | Unknown. FILL IN.
CM+ | Unknown. FILL IN.
CMSynergy | Unknown. FILL IN.
Co-Op | Unkown. FILL IN.
Darcs | Unknown.
Git | As detailed in the Git FAQ: "Git has a rename command git mv, but that is just a convenience. The effect is indistinguishable from removing the file and adding another with different name and the same content."
LibreSource Synchronizer | Unknown. FILL IN.
Mercurial | No. the Mercurial book says: "When you use the 'hg rename' command, Mercurial makes a copy of each source file, then deletes it and marks the file as removed. "
Monotone | Unknown. FILL IN.
OpenCM | Unknown.
Perforce | No, renames are not intelligent.
PureCM | Unknown. FILL IN.
SourceAnywhere | Unknown. FILL IN.
Subversion | "svn help me" says "Note: this subcommand is equivalent to a 'copy' and 'delete'." There's a bug report about it.
Superversion | No. Renames are not supported.
svk | Same as Subversion.
Team Foundation Server | Unknown. FILL IN.
Vesta | Unknown. FILL IN.
Visual SourceSafe | No, renames are not intelligent.

### File and Directories Copies

Does the version control system support copying files or directories to a different location at the repository level, while retaining the history?

CVS | No. Copies are not supported.
AccuRev | Copying is supported through symbolic links (but all linked files are treated as the same file version). Moves are fully supported with the history retained.
Aegis | No. Copies are not supported.
Arch | No. Copies of files and directory structures are not supported.
Bazaar | No. Copies are not supported.
BitKeeper | Yes. Copies are supported.
ClearCase | Yes, through use of hard links. (But some limitations in Windows environments)
CM+ | Yes. An inexpensive operation that can be used for sharing files in multiple places. On deploy, you have the option of deploying only one of the shared files or all of them.
CMSynergy | Yes, and it's a very cheap operation (update the target directory to include the new file/directory).
Co-Op | Copying doesn't retain history, moving does.
Darcs | No. Copies of files and directory structures are not supported.
Git | No. Copies are not supported.
LibreSource Synchronizer | No, copies will start their own history.
Mercurial | Yes. Copies are supported
Monotone | Yes. Copies are supported
OpenCM | No. Copies are not supported.
Perforce | Copies are supported (though, because of its architecture, I don't know how well)
PureCM | Yes. Copies are supported.
SourceAnywhere | Copying doesn't retain history, moving does.
Subversion | Yes. And it's a very cheap operation (O(1)) that is also utilized for branching.
Superversion | No. Copies are not supported.
svk | Yes. Same as subversion.
Team Foundation Server | Yes - you can create a branch. But the GUI has no option to view the old history. The Power-Tool tfpt has the option /followbranches to show the history of the file branch's ancestors
Vesta | Yes. A new package/branch can be based on any existing version without affecting the past history. (This is also an O(1) operation.)
Visual SourceSafe | Yes. Copies are supported up to a point.

### Remote Repository Replication

Does the system support cloning a remote repository to get a functionally equivalent copy in the local system? That should be done without any special access to the remote server except for normal repository access.

CVS | Indirectly, by using CVSup by John Polstra (which requires running the cvsupd daemon on the server)
AccuRev | Yes.
Aegis | Yes.
Arch | Yes.
Bazaar | Yes.
BitKeeper | Yes.
ClearCase | Not really applicable for clearcase, but see next point.
CM+ | Yes. CM+MultiSite can be configured to clone a repository so that it continues to act as a single repository. Options include cloning only from the main site (i.e. not allowing updates from the clone) and restricting the set of files transferred to a cloned site.
CMSynergy | Yes, as long as you have the (more expensive) Distributed package.
Co-Op | Repositories are always replicated on local machines. There is no central server.
Darcs | Yes.
Git | Yes. This is very intrinsic feature of Git.
LibreSource Synchronizer | Yes, but is not documented and its based on the dataflow feature of the LibreSource Synchronizer.
Mercurial | Yes.
Monotone | Yes.
OpenCM | No.
Perforce | Yes. Via the Perforce Proxy (P4P) tool.
PureCM | No. (But a proxy feature is planned for inclusion in the next releases.)
SourceAnywhere | Not directly possible with the included GUI or command line tools; Some SQL Server tool might be useable.
Subversion | Indirectly, by using Chia-liang Kao's SVN::Mirror add-on or Shlomi Fish' SVN-Pusher utility.
Superversion | Yes.
svk | Yes.
Team Foundation Server | TFS Proxy is available but the replica isn't an equivalent copy.
Vesta | Yes. Replication is a fundamental part of the design.
Visual SourceSafe | Not directly possible with the included GUI or command line tools; ssarc and ssrestor might be useable

### Propagating Changes to Parent Repositories

Can the system propagate changes from one repository to another?

CVS | No.
AccuRev | With AccuReplica, the replica server has all the meta-data and fetches file data as needed by replica users; all write operations pass automatically from the replica to the master server.
Aegis | Yes.
Arch | Yes.
Bazaar | Yes.
BitKeeper | Yes.
ClearCase | Yes, using Clearcase Multisite.
CM+ | Yes. In CM+MultiSite, changes made at the slave are, by default, propagated to the Main(master) library, as well as to all other Clones (slaves). You may also propagate changes between unrelated repositories containing some of the same source.
CMSynergy | Yes, as long as you have the (more expensive) Distributed package.
Co-Op | It's a peer-to-peer system, which keeps all replicas of the repository in sync.
Darcs | Yes.
Git | Yes. (The Linux kernel development process uses this extremely often).
LibreSource Synchronizer | Yes, it's what we call a dataflow.
Mercurial | Yes.
Monotone | Yes.
OpenCM | No.
Perforce | Unknown. Probably Not.
PureCM | No.
SourceAnywhere | Not directly possible with the included GUI or command line tools; Some SQL Server tool might be useable.
Subversion | Yes, using either Chia-Ling Kao's SVN::Mirror script or the svn-push utility by Shlomi Fish.
Superversion | No.
svk | Yes.
Team Foundation Server | No.
Vesta | Yes.
Visual SourceSafe | Not directly possible with the included GUI or command line tools; ssarc and ssrestor might be useable

### Repository Permissions

Is it possible to define permissions on access to different parts of a remote repository? Or is access open for all?

CVS | Limited. "pre-commit hook scripts" can be used to implement various permissions systems.
AccuRev | Yes. Access can be defined per stream (branch) using access control lists.
Aegis | Yes. Aegis relies on the UNIX permissions system to implement permissions for files in the repository.
Arch | Yes. It is possible to define permissions on access to different parts of a remote repository based on the permission systems of the underlying protocol.
Bazaar | Basic access control can be implemented through a contributed hook script. ACL support for the Bazaar server is planned.
BitKeeper | FILL IN
ClearCase | Yes, a unix-like permissions model is used, which maps onto Windows domain-based authentication in multi-platform environments.
CM+ | Yes. Permissions are defined by data, primarily, not by location. If location is a part of the data, it may be used to define permissions by location. Permissions may apply to a branch, file, problem report, test case, etc. Access may be extended based on peer group, manager, and access lists.
CMSynergy | No, though a single server can serve many repositories.
Co-Op | First access (joining the project) requires administrator's approval. Subsequent access to that project is not controlled.
Darcs | No.
Git | No, but a single server can serve many repositories. Also, UNIX permissions can be used to some extent.
LibreSource Synchronizer | Permissions are set for the whole repository or branch.
Mercurial | Yes. It is possible to lock down repositories, subdirectories, or files using hooks.
Monotone | Yes. It is possible to restrict incoming changes from certain sources to be performed only in certain parts of the repository.
OpenCM | Permissions are defined on a per-branch basis.
Perforce | Yes. (more than half a dozen of permission levels that can be set in a file by file basis)
PureCM | Yes. (more than half a dozen of permission levels that can be set in a file by file basis)
SourceAnywhere | Yes. SourceAnywhere Server Manager can define access to a repository per user or group and user access rights to a project.
Subversion | Yes. The WebDAV-based service supports defining HTTP permissions for various directories of the repository.
Superversion | No.
svk | Same as subversion.
Team Foundation Server | Yes. You get set permissions for each team project, folder, file.
Vesta | Yes. Access permissions for each package (the unit of checkout/checkin) can be different. Access permissions for a branch can be different from the basis package.
Visual SourceSafe | Project specific permissions (read, write, delete, destroy) can be set per user; but see "Networking Support": this makes "Repository Permissions" a hindrance to accidental damage but cannot prevent intentional damage.

### Changesets' Support

Does the repository support changesets? Changesets are a way to group a number of modifications that are relevant to each other in one atomic package, that can be cancelled or propagated as needed.

CVS | No. Changes are file-specific.
AccuRev | Yes, AccuRev provides robust functionality for change sets (called change packages in AccuRev) including viewing differences by change packages and merging changes from stream to stream by change package.
Aegis | Yes. Changesets are supported.
Arch | Yes. Changesets are supported.
Bazaar | Yes. Changesets are supported.
BitKeeper | Yes. Changesets are supported.
ClearCase | Not supported in this way. Extensive branching support gives similar benefits. (eg each changeset can be given a branch). Also optional UCM feature gives something like this (each changeset is a "stream").
CM+ | Yes. Change packages are known as updates. By default, an update is required to make any change. The update may be checked-in, differenced, promoted, retrieved, propagated, yanked (i.e. removed from history), etc. each in a single operation. Baseline alignment is performed based on the status (i.e. promotion level) of the update. Updates also record changes to directory structure: move, add, remove.
CMSynergy | Yes. Changesets (or tasks) are fundamental to the way Synergy works.
Co-Op | Yes. Changesets are the default.
Darcs | Yes. Changesets are supported.
Git | Yes, Changesets are supported, and there's some flexibility in creating them.
LibreSource Synchronizer | Partial support. There are implicit changeset that are generated on each commit.
Mercurial | Yes. Changesets are supported.
Monotone | Yes. Changesets are supported.
OpenCM | Yes. Changesets are supported.
Perforce | Yes. Changesets are supported.
PureCM | Yes. Changesets are supported.
SourceAnywhere | Not exactly. SourceAnywhere uses a related concept of configurations instead, which some has similar properties.
Subversion | Partial support. There are implicit changeset that are generated on each commit.
Superversion | Partial support. Changes are grouped into changesets, but cannot be cancelled invididually yet.
svk | Same as subversion.
Team Foundation Server | Yes. Changesets are only possibility.
Vesta | Not exactly. Vesta uses a related concept of configurations instead, which some has similar properties.
Visual SourceSafe | No. Changes are file-specific.

### Tracking Line-wise File History

Does the version control system have an option to track the history of the file line-by-line? I.e., can it show for each line at which revision it was most recently changed, and by whom?

CVS | Yes. cvs annotate
AccuRev | Yes. Available from both the gui and cli.
Aegis | Yes. aeannotate
Arch | Not in the command line client, but ViewARCH, a web-interface for Arch, has it.
Bazaar | Yes. (bzr annotate).
BitKeeper | Yes. (bk annotate)
ClearCase | Yes, "cleartool annotate"
CM+ | Yes. View revision tags.
CMSynergy | Probably, if you're a sufficiently proficient hacker with their scripting language.
Co-Op | Not directly, but it's possible to compare any two versions using a visual differ.
Darcs | Yes. (darcs annotate)
Git | Yes. (git blame).
LibreSource Synchronizer | Yes, locally without any server connection with the standard graphical Java client.
Mercurial | Yes. (hg annotate)
Monotone | Yes, as of version 0.19.
OpenCM | Unknown. Probably not.
Perforce | Yes, an annotation feature is present.
PureCM | Yes, annotation is available through the GUI.
SourceAnywhere | Yes. (SAW annotate)
Subversion | Yes. (svn blame)
Superversion | No.
svk | Yes. (svk blame)
Team Foundation Server | Yes. (tf annotate).
Vesta | No, but it would be easy to implement a tool that did this, as the Vesta repository provides direct filesystem access to all versions.
Visual SourceSafe | Not directly, but it's possible to compare any two versions using a visual differ.

## Features

### Ability to Work only on One Directory of the Repository

Can the version control system checkout only one directory of the repository? Or restrict the check-ins to only one directory?

CVS | Yes.
AccuRev | Yes. AccuRev provides functionality to define feature streams in which only the subset of code is seen. A group of developers can then be retricted to work only from that stream so they are only allowed to check in changes to that subset of code.
Aegis | No. All changes are made repository-wide.
Arch | It is possible to commit only a certain directory. However, one must check out the entire repository as a whole.
Bazaar | For checkouts: No. For checkins: Yes.
BitKeeper | No. All changes are made repository-wide.
ClearCase | Yes, using snapshot view load rules.
CM+ | Yes. Any arbitrary set can be checked out and worked on. Similarly, arbitrary restrictions may be applied for check-in, including file ownership.
CMSynergy | Yes and no. Files and directories are checked out and in individually, however you have to work in the context of a project, which consists of one or more directories.
Co-Op | No. All changes are made to a project as a unit, but it's possible to access each file's history separately.
Darcs | It is possible to commit only a certain directory. However, one must check out the entire repository as a whole.
Git | No. However, commits could be restricted somewhat, see the "Repository Permissions".
LibreSource Synchronizer | It is possible to commit only a certain directory. However, one must check out the entire repository as a whole.
Mercurial | It is possible to commit changes only in a subset of the tree. There are plans for partial checkouts.
Monotone | It is possible to commit changes only in a subset of the tree. However, one must extract the entire tree to work on it.
OpenCM | No. All changes are made to a project as a unit
Perforce | Yes. Changes to a sub-directory of the repository are supported.
PureCM | Yes.
SourceAnywhere | Yes. SourceAnywhere can define the user access right to each project and users can be restricted to work only on the projects they have check out/in right.
Subversion | Yes.
Superversion | No.
svk | Yes.
Team Foundation Server | Yes.
Vesta | Yes and no. The unit of checkout/checkin (called a package) is a directory tree. Most projects use more than one. Once created, a package must be checked out/in as a unit.
Visual SourceSafe | Yes.

### Tracking Uncommited Changes

Does the software have an ability to track the changes in the working copy that were not yet committed to the repository?

CVS | Yes. Using cvs diff
AccuRev | Yes. The functionality is available through both the GUI and the command line interface.
Aegis | Yes. Using aediff
Aegis | Yes. Using aediff.
Arch | Yes, using "tla changes".
Bazaar | Yes, using "bzr diff".
BitKeeper | Yes. Using bk diff.
ClearCase | Yes, "cleartool diff"
CM+ | Yes. Use Updates | Delta | Delta Update. Or right click a file or directory and do a compare to workspace.
CMSynergy | Yes, either using integrated diff tool or user-configured external diff tool
Co-Op | Yes, using built-in visual differ/editor.
Darcs | Yes, using "darcs whatsnew".
Git | Yes. Also, branches are very lightweight in Git, and could be considered a kind of storage for "uncommitted" code in some workflows.
LibreSource Synchronizer | Yes, with the Synchronizer Studio (default Java client) or with the standard diff command (diff -r . .so6/xxx/REFCOPY/)
Mercurial | Yes. Using hg diff.
Monotone | Yes. In a similar fashion to CVS.
OpenCM | Yes. Using cm diff
Perforce | Yes.
PureCM | Yes.
SourceAnywhere | Yes. Using saw diff.
Subversion | Yes. Using svn diff
Superversion | Yes. Local changes are detected and shown immediately. Changes can be collected in a local buffer before being committed to the repository.
svk | Yes. Using svk diff
Team Foundation Server | Yes. Using tf diff or "Pending Changes" in Visual Studio.
Vesta | Yes. Intermediate immutable snapshots can be taken during an active checkout (with vadvance). These intermediate versions can be treated just like checked in versions: they can be replicated to other repositories and used as the basis for branches.
Visual SourceSafe | Yes, using integrated diff tool.

### Per-File Commit Messages

Does the system have a way to assign a per-file commit message to the changeset, as well as a per-changeset message?

CVS | No. Commit messages are per change.
AccuRev | No. Commit messages are per change.
Arch | No.
Bazaar | With respect to pure Bazaar: No. At least one plugin (bzr-gtk) supports it though.
BitKeeper | Yes. It is possible to have a per-file commit message
ClearCase | Yes, assuming a comment on the branch is sufficient for a per-changeset message.
CM+ | Yes. Out of the box CM+ is configured to prompt for messages (i.e. comments) only per change. However, the schema is pre-configured so that you may prompt on a per file basis as well (typically done at checkout time as the entire change is normally checked in with a single operation.
CMSynergy | Yes.
Co-Op | No. Commit messages are per change. They go to all project members and update their repositories.
Darcs | No.
Git | No. Commit messages are per changeset.
LibreSource Synchronizer | No. Commit messages are per changeset.
Mercurial | No.
Monotone | Yes. It is possible to attach a comment to a certain file at a certain revision.
OpenCM | Unknown.
Perforce | No. Commit messages are per change.
PureCM | No. Commit messages are per change.
SourceAnywhere | No. There is no such feature.
Subversion | No. There is no such feature.
Superversion | Yes.
svk | No. There is no such feature.
Team Foundation Server | No. Commit messages are per changeset.
Vesta | Not exactly. The unit of checkin is a directory, and commit messages are assigned at that level, not to individual files. Since configurations are also versioned, they also have commit messages.
Visual SourceSafe | Since changesets are not supported, yes.

## Technical Status

### Documentation

How well is the system documented? How easy is it to get started using it?

CVS | Excellent. There are many online tutorials and resources and an online book. The command line client also provides an online comprehensive help system.
AccuRev | Excellent. There is a full set of documentation available in pdf format available at AccuRev Documentation as well as context-sensitive help in the GUI.
Aegis | Medium. The documentation is given in several large scope troff documents, that are only usable as not-so-PDFish PDF documents, and as text documents that lack any formatting. It is very hard to get started using it with the online resources. The content is of good quality, but otherwise not made very accessible.
Arch | Medium. There are two online tutorials and a comprehensive online documentation. The command line client also supplies a reference page. However, some of the documentation is out of date or incomplete.
Bazaar | Excellent. Apart from online help in the command line client there exist tutorials, a reference card ("Quick Start Guide"), several full fledged guides and references, and documents on specialized topics, such as migration from other VCS systems and different workflows. The documentation comes in html and plain-text formats. The API of the underlying library is fully documented. In the UI design of the command line client special attention was paid to make it easy to get started with Bazaar.
BitKeeper | Very good. There is a comprehensive help at the BitKeeper site. Each command is documented in its own man page, and the client contains a help tool that offers an integrated help system.
ClearCase | Extensive online help in Windows Help / UNIX manpage format, also PDF-based documentation. However the complexity of the tool can mean a lengthy ramp-up time.
CM+ | Very good. There is a self-demo/tutorial to get you started quickly. Administration is minimal. So normal developer use requires only a 1 to 2 hour training session (or equivalent guide) to introduce you to concepts and capabilities (e.g. like updates, options). Customization documentation is also extensive but should normally be accompanied by a 2-day to 4-day course for GUI, Process, Data and Application set customization.
CMSynergy | Medium. Lots of books, plus somewhat clunky set of HTML pages, but has some radical concepts which can cause real problems really quickly. They recommend a day's training for basic users, more for more advanced users. Took a while to become fluent.
Co-Op | Very good. Step-by-step tutorial and HTML help is included.
Darcs | Good. The manual contains a brief tutorial and a solid reference. Every sub-command can print its usage. Because the command-set is small and the model is simple, many users find it easy to get started.
Git | Medium. The short help is too terse and obscure. The man pages are extensive, but tend to be confusing. The are many tutorials.
LibreSource Synchronizer | Medium. There are an online tutorial and some comprehensive online documentation. Installing and getting started with the GUI is very easy though. (update/commit-next-next-next-finished)
Mercurial | Very good. There is a companion book and a wiki. Every command has integrated help.
Monotone | Good. There's an overview and tutorial written in Texi, and a man page. The client supplies documentation for every command.
OpenCM | Well documented.
Perforce | Very Good (html and command line help)
PureCM | Very Good (html and command line help)
SourceAnywhere | Good. There's an overview and tutorial on the web site, and integrated help for every command.
Subversion | Very good. There is a free online book and some online tutorials and resources. The book is written in DocBook/XML and so is convertible to many different formats. The command-line client also provides a good online help system that can be used as a reference.
Superversion | Fairly poor. There are two tutorials, but there is no reference. Installing and getting started with the GUI is very easy though.
svk | Relatively poor, but improving. There's a work-in-progress book as well as the Wiki and some external Articles and Tutorials.
Team Foundation Server | Good. A comprehensive documentation in the MSDN Library. Many Step-by-Step tutorial videos online.
Vesta | Quite thoroughly (HTML, man pages, published papers, a book-length research report).
Visual SourceSafe | Medium. Help file which is sometimes useful. However, the interface is reasonably intuitive so documentation isn't needed as much.

### Ease of Deployment

How easy is it to deploy the software? What are the dependencies and how can they be satisfied?

CVS | Good. Out of being the de-facto standard, CVS is available on most systems and is easy to deploy.
AccuRev | Excellent. All that is required is to download the binaries for the appropriate platform and run the installer. The installation package is self-contained. No additional software is needed. AccuRev supports most UNIX, Linux, and Windows platforms and deploying AccuRev to a multi-platform environment is straight-forward.
Aegis | The Aegis binary should be installed as SUID-root, and so requires root privileges to install. It also not very portable to Win32 systems. Other than that, Aegis supports an easy autoconf or RPM/apt-based installation process.
Arch | Excellent. An arch service is nothing but a filesystem-space hosted by any of its supported protocols (FTP, SFTP, WebDAV, etc.). The arch client is written in C, and is portable across UNIX systems (and on Win32 only with a UNIX emulation layer).
Bazaar | Very easy. Bazaar has an installer for MS Windows and packages for some major Linux distributions, FreeBSD, and Mac OS X. The dependencies for manual installation are listed on the Bazaar website.
BitKeeper | Good. All that is required is downloading a binary for the system and installing it using the installation script. The package is self-contained and is easy to set up.
ClearCase | Poor. Clearcase is very difficult to install in general. At least, setup for a new site is quite complex. Installing additional servers (eg repository servers) is less so.
CM+ | Yes. Typical installation need only be done on the server (with a single shortcut established on the client). This assumes file system connectivity. For IP only connectivity, installation is also required on remote clients. Installation is typically a couple of minutes. No dependencies unless web interface is used, in which case an Apache server is required. A download is available from Neuma's web site and takes you right into a self-guided fully working demo version.
CMSynergy | Medium. There is a detailed install guide for setting it up using a binary kit and a set of scripts. However it still took several tries to get it properly installed and configured. The Windows client has a slightly clunky Windows installer.
Co-Op | Very easy to deploy, since there is no central server. Can be configured to use e-mail or LAN (or both) for synchronization. For e-mail, requires MAPI-compliant e-mail client.
Darcs | Very good. darcs requires few external libraries, however you need the Glasgow Haskell Compiler if you cannot find a binary. To start working, just "darcs init".
Git | Good. Binary packages are available for modern platforms. C compiler and Perl are required. Requires cygwin on Windows, and has some UNIXisms.
LibreSource Synchronizer | Excellent. It is managed by JavaWebStart with links on any LibreSource repository web page. (links: create workspace, update, commit, studio...)
Mercurial | Excellent. Binary packages are available for all popular platforms. Building from source requires only Python 2.3 (or later) and a C compiler.
Monotone | Excellent. It is possible to copy or compile the executable to the user's machine, without any configuration or external dependencies.
OpenCM | Very good. Install the RPM, or build from tarball and install the init script.
Perforce | Very good. Perforce is very easy to deploy.
PureCM | Very good. PureCM is very easy to deploy.
SourceAnywhere | Excellent. Dynamsoft SourceAnywhere is extremely easy to install. It is totally written in C++ from scratch, which means that you don't need any additional components and frameworks to support the installation.
Subversion | A Subversion service requires installing an Apache 2 module (if one wishes to use HTTP as the underlying protocol) or its own proprietary server. The client requires only the Subversion-specific logic and the Neon WebDAV library (for HTTP). Installation of the components is quite straightforward, but will require some work, assuming Subversion does not come prepackaged for one's system.
Superversion | If Java 1.4 is installed, deployment of Superversion usually takes two clicks.
svk | In addition to installing subversion, users are required to install the subversion perl bindings and a few modules from CPAN.
Team Foundation Server | Installation is quite complex. Needs IIS, MS-SQL Server and Reporting Services. A own installation guide with step-by-step guide is available. Allows separating in data and app tier.
Vesta | Medium to Good. There is a detailed installation guide for setting it up using a binary kit. RPMs and Debian packages have been recently released. There are no dependencies on other software. There is a bootstrap package available to build Vesta from using "make".
Visual SourceSafe | Very good - an installation package which does the work. When you create a repository it installs the exe's in a directory and you can run them from there if you need to.

### Command Set

What is the command set? How compatible is it with the commands of CVS (the current open-source defacto standard)?

CVS | A simple command set that includes three most commonly used commands (cvs commit, cvs update and cvs checkout) and several others.
AccuRev | Very extensive but not compatible with cvs.
Aegis | A complex command set that involves many operations just to get started. Not CVS-compatible. (albeit support for such basic operations was contemplated) Note that Aegis is a Software Configuration Management system and not just a simple version control system, which may justify this extra complexity.
Arch | Many commands are compatible with CVS or BitKeeper. However, there are many other commands for it for different uses. Aliasing of commands is possible so it it may be possible to make it more compatible.
Bazaar | Tries to follow CVS conventions, but deviates where there is a different design.
BitKeeper | A CVS-like command set with some easy-to-get-used-to complications due to its different way of work and philosophy.
ClearCase | Excellent. All tools are available through the command-line. Not very compatible with CVS though.
CM+ | CM+ has several dozen commands that can be used both for operation and configuration of the product. As CM+ is change-based, commands are substantially different than CVS. The GUI is used primarily and implemented on top of the command set. As well, CM+ covers a full ALM suite and can be extended beyond, so there are many more generic commands for browsing, reporting, etc.
CMSynergy | An extensive and powerful command set, which has some CVS similarity, though the architecture is so different that it quickly moves away for anything but the basics.
Co-Op | Basic commands are compatible with CVS.
Darcs | The command set is fairly compact and the core commands are easy to understand. Follows CVS in a few places, but since the model is different most commands are unique.
Git | Command set is very feature-rich, and not compatible with CVS.
LibreSource Synchronizer | Basic commands available (commit/update), but it's really simple to use the GUI. Ant task are also available.
Mercurial | Tries to follow CVS conventions, but deviates where there is a different design.
Monotone | Tries to follow CVS conventions, but deviates where there is a different design.
OpenCM | A CVS-like command set that is familiar to existing CVS users.
Perforce | Very extensive but not compatible with CVS.
PureCM | A CVS-like command set which is easy to get used to for CVS-users.
SourceAnywhere | Very extensive but not compatible with CVS.
Subversion | A CVS-like command set which is easy to get used to for CVS-users.
Superversion | There is little need to memorize a command set because all actions take place in a GUI. A part of the terminology used in the application is borrowed from CVS.
svk | A CVS-like command set which is easy to get used to for CVS-users.
Team Foundation Server | The command set allows more operations than the GUI but isn't compatible with CVS.
Vesta | The command set is unrelated to CVS. Most of the time, users use about 5 commands. Few ever need to know more than about 20 commands.
Visual SourceSafe | A bit of an afterthought. It's possible to do basic things, but it's really geared up for using the GUI.

### Networking Support

How good is the networking integration of the system? How compliant is it with existing protocols and infra-structure?

CVS | Good. CVS uses a proprietary protocol with various variations for its client/server protocol. This protocol can be tunneled over an SSH-connection to support encryption.
AccuRev | Good. (proprietary protocol using TCP/IP)
Aegis | Poor. Aegis is filesystem-oriented and so can be networked only via NFS (network file-system) or a similar protocol. There exists some HTTP-functionality, but it is quite limited.
Arch | Excellent. Arch can utilize a multitude of protocols for its service, which is nothing but a dumb remote filesystem server. Currently supported protocols include FTP, SFTP, WebDAV (remote file access over HTTP), as well as any remote filesystem protocol (NFS, SMB).
Bazaar | Excellent. Works natively over HTTP (read-only), FTP and SFTP without having Bazaar installed at the remote end. Works over HTTP, SSH and a custom protocol when talking to a remote Bazaar server. Supports RSYNC and WebDAV (experimental) through plugins.
BitKeeper | Good. Repositories can be checked out from remote over HTTP, and BitKeeper also sports its own proprietary protocol for communicating between one repository and the other.
ClearCase | Poor. Uses an *extremely* chatty RPC protocol for most clearcase operations, plus NFS or SMB for accessing the files themselves. Typically servers should be deployed locally (ie on the same LAN) as the client workstations for acceptable performance.
CM+ | Very good. File system connectivity, TCP/IP connectivity and Web connectivity may be intermixed. MultiSite connectivity is over TCP/IP, as is License server. Works well with SSH, NFS, SMB, etc.
CMSynergy | Good (single TCP/IP socket)
Co-Op | Uses the simplest LAN interface: copying files between shared directories.
Darcs | Good. Darcs supports getting patches over HTTP, and getting and sending patches over SSH and email.
Git | Excellent. Can use native Git protocol, but works over rsync, ssh, HTTP and HTTPS also.
LibreSource Synchronizer | Good. Use of HTTP to get through firwalls.
Mercurial | Excellent. Uses HTTP or ssh. Remote access also works safely without locks over read-only network filesystems.
Monotone | Good. Uses a custom protocol called "netsync".
OpenCM | Good. Uses its own proprietary client/server protocol.
Perforce | Good. (single TCP/IP socket)
PureCM | Good. (single TCP/IP socket)
SourceAnywhere | Good. (single TCP/IP socket)
Subversion | Very good. The Subversion service can use either WebDAV+DeltaV (which is HTTP or HTTPS based) as its underylying protocol, or its own proprietary protocol that can be channeled over an SSH connection.
Superversion | Good. Network support based on RMI is integrated seamlessly. Encryption and HTTP tunnelling are planned for the near future.
svk | Very good. svk uses SVN::Mirror to retrieve remote repository. There has been plans to add VCP support to SVN::Mirror so it will be able to mirror from arbitary remote version control systems.
Team Foundation Server | Good. Use of HTTP(S).
Vesta | Networking is inherent to the system. The repository exports both an NFS interface and an RPC interface. The checkout and checkin tools automatically contact a remote repository when required to perform an operation.
Visual SourceSafe | VSS uses a Windows network share which has to be writable for the VSS users (since this means doubling maintenance for new users). Add user in VSS and to share permissions. the share is most often world-writable, as is the default when creating a share) It does not perform well over a slow network connection.

### Portability

How portable is the version-control system to various operating systems, computer architectures, and other types of systems?

CVS | Good. Client works on UNIX, Windows and Mac OS. Server works on UNIXes and on Windows with a UNIX emulation layer.
AccuRev | Excellent. The server runs on most UNIX, Linux and Windows platforms. The client runs on all of these platforms and on Mac OS X.
Aegis | Medium. The source is portable across all UNIXes, but the Windows version work only using cygwin, and even then not entirely natively.
Arch | Good. The source is portable across all UNIXes, but requires a UNIX emulation layer on Windows. (need to verify). A service can be hosted on any platform that sports a suitable Internet service.
Bazaar | Works on MS Windows, Linux, Mac OS X, FreeBSD, UNIX, and basically on any system that has a recent Python port. With case-insensitive file systems there are some issues that can be avoided by using a graphical frontend. On MS Windows there is a plugin to support tracking of symlinks even if they are not supported natively by the file system.
BitKeeper | Very good. Binaries are available for most common UNIX systems and for Windows 98 and above.
ClearCase | Medium. Available on Windows, and several selected flavours of UNIX (not including MacOS X, or any other Linux other than Red Hat).
CM+ | Good. Clients and Servers work on Unix, Linux, and Windows. MAC OS X port pending. Moving server from one platform to another is a copy operation only. Can have different platforms for different servers in a MultiSite configuration. Easily configurable Web client also supported. No CR/LF issues. Scripts are all portable as well.
CMSynergy | Very good - various flavours of Unix, Windows (only NT family for the server), VMS, and possibly other systems.
Co-Op | Windows only: starting with Win95.
Darcs | Very good. Supports many UNIXes, Mac OS X, and Windows, and is written in a portable language.
Git | The client works on most UNIXes, but not on native MS-Windows. The cygwin build seems to be workable, though.
LibreSource Synchronizer | Excellent. Clients and servers work on any Java 1.5-compatible platform. (Windows, Linux and Mac OS X )
Mercurial | Excellent. Runs on all platforms supported by Python. Repositories are portable across CPU architectures and endian conventions.
Monotone | Excellent. Executable is portable across all UNIXes and Win32.
OpenCM | Good. Portable across all UNIX systems.
Perforce | Excellent. Runs on UNIX, Mac OS, BeOS and Windows.
PureCM | Excellent. Client and Server run on Windows, Linux, Solaris and other UNIXes. The client also runs on Mac OS X.
SourceAnywhere | Good. The server runs on Windows only. Clients can work on any platform that SWT (Standard Widget Toolkit) supports, including Windows, Linux, Mac, Solaris, AIX, HP-UX, SCO Unix, FreeBSD and so on.
Subversion | Excellent. Clients and Servers work on UNIX, Windows and Mac OS X.
Superversion | Excellent. Clients and servers work on any Java 1.4-compatible platform. There is official support for Windows, Linux and OS/2.
svk | Good. Clients requires subversion and its perl bindings.
Team Foundation Server | The Server and Client needs Windows. A thirdparty company, Teamprise, has developed a client for Eclipse, which means Linux, Mac and other UNIXes support. The Project SvnBridge allows access using SVN clients but needs to run on Windows.
Vesta | Good. It should be portable to any UNIX system. Currently it runs on Digital/Compaq/HP Tru64 UNIX and Linux on several different CPU architectures. Ports to Solaris and FreeBSD are planned but haven't begun yet.
Visual SourceSafe | The Microsoft Product is Windows only. MainSoft ships a version of it for some UNIX platforms.

## User Interfaces

### Web Interface

Does the system have a WWW-based interface that can be used to browse the tree and the various revisions of the files, perform arbitrary diffs, etc?

CVS | Yes. CVSweb, ViewVC, Chora, and wwCVS.
AccuRev | No.
Aegis | Yes.
Arch | There's ViewARCH, and ArchZoom which are works in progress.
Bazaar | Yes, several: Loggerhead, Webserve, Bzrweb, and Trac.
BitKeeper | Yes. Its own built-in web-interface.
ClearCase | Yes. Web views are supported.
CM+ | Yes. Can be configured to restrict which operations are allowed by which users, so that customers may access their requests without seeing development team data.
CMSynergy | Possibly.
Co-Op | Since this functionality is always available locally, there is no need for web interface.
Darcs | darcs.cgi is included in the distribution.
Git | Yes. Gitweb is included in distribution.
LibreSource Synchronizer | Yes, without diff features but with a better awareness support. (allow to know at any time on each version each one is working on)
Mercurial | Yes. The web interface is a bundled component.
Monotone | No.
OpenCM | No.
Perforce | Yes, P4Web.
PureCM | Yes.
SourceAnywhere | Currently not.
Subversion | Yes. ViewVC, SVN::Web, WebSVN, ViewSVN, mod_svn_view, Chora, Trac, SVN::RaWeb::Light, SVN Browser, Insurrection and perl_svn. Aside from that, the Subversion Apache service provides a rudimentary web-interface.
Superversion | No.
svk | Yes. Same as Subversion.
Team Foundation Server | Web Access is available as download for free.
Vesta | Yes: Vestaweb.
Visual SourceSafe | It is possible to code one using the API, but no official or third-party one exists.

### Availability of Graphical User-Interfaces.

What is the availability of graphical user-interfaces for the system? How many GUI clients are present for it?

CVS | Very good. There are many available GUIs: WinCVS, Cervisia (for KDE), TortoiseCVS (Windows Explorer plug-in).
AccuRev | A single, comprehensive, java-based GUI is provided. The GUI has the same look-and-feel on all platforms.
Aegis | There is tkaegis.
Arch | There are tlator, Octopy, and ArchWay and possibly others under development.
Bazaar | There are several graphical frontends in development, see the Bazaar Plugins page and the Third-party Tools page. Notable are QBzr (Qt) and bzr-gtk (GTK+), which can be considered beta quality. Work is also being done on integrating Bazaar with Windows Explorer, Eclipse, Nautilus, and Meld.
BitKeeper | Good. BitKeeper ships with several GUIs for performing common tasks. I'm not aware of any third-part GUIs.
ClearCase | Supplied for both Windows and UNIX. GUI tools are typically not as solid as the command-line tools though.
CM+ | Excellent. Windows and Unix/Linux GUI as well as web GUI. Extensively configurable via simple menu files, browser files, etc. Can customize the set of to-do lists by user/role, same for menus, pop-up menus, default visible tabbed reports, etc. GUI also used for all admin and for process and data schema customization. Also plug-in for Visual Studio, Eclipse, etc. and File Browser (Windows).
CMSynergy | A couple of GUIs. A motif-based one (even on Windows) allows most functionality but is clunky. A nicer Java one allows developer work but not much administrative stuff. Has an SCCI plug-in, though it doesn't handle network problems well.
Co-Op | The system is GUI-based by design.
Darcs | None to speak of. (There is a modest graphical interface to a few commands in the distribution, but it is not being developed currently.)
Git | Gitk is included in distribution. Qgit and Git-gui tools are also available.
LibreSource Synchronizer | One written in Java/SWING and available on any OS that is automatically launched from the repository web page and another one which is an Eclipse plugin.
Mercurial | History viewing available with hgit extension; check-in extension (hgct) makes committing easier. Some third-party IDEs and GUI tools (e.g. eric3, meld) have integrated Mercurial support.
Monotone | No GUIs are available.
OpenCM | No GUIs are available.
Perforce | Yes, P4Win and others based on the available libp4 library.
PureCM | Cross-platform GUI for Windows, Linux, Mac OS X and other UNIXes.
SourceAnywhere | The system is GUI-based by design.
Subversion | Very good. There are many available GUIs: RapidSVN (cross-platform), TortoiseSVN (Windows Explorer plug-in), Jsvn (Java), etc. Most of them are still under development.
Superversion | A GUI is integrated.
svk | No GUIs are available.
Team Foundation Server | TFS client integrates into Visual Studio.
Vesta | No GUIs are available, but the repository has a C++ API, and it is not hard to write one. (At least three different project-specific ones have been written by users at Compaq and Intel.)
Visual SourceSafe | Standalone GUI comes with it, plus SCCI plug-in for MS Visual Developer Studio. There is an Eclipse plug-in.

## License

What are the licensing terms for the software?

CVS | GNU GPL (open source)
AccuRev | Proprietary, named-user licensing.
Aegis | GNU GPL (open source)
Arch | GNU GPL (open source)
Bazaar | GNU GPL (open source)
BitKeeper | Proprietary, binary only license. Pay per use license, with an option for a costless license for developers of open-source software. Used to have a gratis, downloadable license, which was intended for the develpoment of open source software. It had a problematic license, and was discontinued starting at April 2005.
ClearCase | Proprietary, with floating license supported. License server contacted for each clearcase operation, which obtains a license to be used for the next 30-60 mins. Prices are several $k per license plus yearly maintenance fee. Typically 1-3 users per license required, depending on activity. Multisite requires additional licensing.
CM+ | Network licenses and user licenses. No minimum checkout time, and automatic license checkin on idle. License server included in product. Professional and Enterprise editions. Enterprise includes customizations, additional applications, and full multiple site capability. One Server license per site. Total license cost per user typically less than $1000 + 18% annual mtce.
CMSynergy | Prices negotiable with salesman. Server is typically roughly 20,000 British Pounds. Clients are 4,000 British Pounds. Per-year costs of 18% of original.
Co-Op | Proprietary, short text key. 30-day full-featured trial. Free to "observers" (members who don't make changes). $159 per workstation.
Darcs | GNU GPL (open source)
Git | GNU GPL v2 (open source).
LibreSource Synchronizer | QPL - The Qt Public License (OpenSource)
Mercurial | GNU GPL (open source)
Monotone | GNU GPL (open source)
OpenCM | GNU GPL (open source), but moving soon to BSD or CPL (also open source).
Perforce | A proprietary, binary only, commercial license. Price starting at $800 per seat for the first year and then a $160 for continuing support for the subsequent years. The latter payment is optional and required only for support, as the product can be used without it. Free for Open Source projects (no support in this case).
PureCM | A proprietary, binary only, commercial license. Price starting at $1000 for 5 users
SourceAnywhere | Proprietary, named-user licensing.
Subversion | Apache/BSD-style license. (open-source)
Superversion | GNU GPL (open-source)
svk | Perl License. (open source)
Team Foundation Server | Commercial license.
Vesta | GNU LGPL (open source)
Visual SourceSafe | VSS Ships with MSDN, and can also be purchased standalone or with other tools.