www/index.html - subversion - Git at Google

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 <font color="red">
 <b>
 If you're using Subversion, we recommend that you join the <a
 href="/servlets/ProjectMailingListList">users@subversion.tigris.org</a>
 mailing list, and read the <a
 href="http://svnbook.red-bean.com/">Subversion Book</a> and <a
 href="/faq.html">FAQ</a>.  You can also ask questions on IRC
 at <tt><a href="irc://irc.freenode.net/">irc.freenode.net</a></tt>,
 channel <tt><a href="irc://irc.freenode.net/svn">#svn</a></tt>.
 </b>
 </font>
 </td>
 </tr>

 </table>

 <h3>What Is Subversion?</h3>

 <table border="0" cellpadding="2" width="98%" bgcolor="white">
 <tr>
 <td width="100%" height="100" bgcolor="#f0f0f0">

 <p>
 The goal of the Subversion project is to build a version control
 system that is a compelling replacement for CVS in the open source
 community.  The software is released under an <a
 href="/project_license.html">Apache/BSD-style</a> open source license.
 </p>

 <p>
 <center>
 <img src="/subversion_logo_hor-468x64.png" alt="Subversion"
      width="468" height="64" align="center"/>
 </center>
 </p>

 <p>
 <h2>Subversion's Features</h2>
 <p>

 <ul>  <!-- list of features -->

 <li><strong>Most current CVS features.</strong>
     <p>Subversion is meant to be a better CVS, so it has most of
     CVS's features.  Generally, Subversion's interface to a particular
     feature is similar to CVS's, except where there's a compelling
     reason to do otherwise.</p>
 </li>

 <li><strong>Directories, renames, and file meta-data are versioned.</strong>
     <p>Lack of these features is one of the most common complaints
     against CVS.  Subversion versions not only file contents and file
     existence, but also directories, copies, and renames.  It also
     allows arbitrary metadata ("properties") to be versioned along
     with any file or directory, and provides a mechanism for
     versioning the `execute' permission flag on files.
  </p>
 </li>

 <li><strong>Commits are truly atomic.</strong>
     <p>No part of a commit takes effect until the entire commit has
     succeeded.  Revision numbers are per-commit, not per-file; log
     messages are attached to the revision, not stored redundantly as
     in CVS.</p>
 </li>

 <li><strong>Apache network server option, with WebDAV/DeltaV
     protocol.</strong>
     <p>Subversion can use the HTTP-based WebDAV/DeltaV protocol for network
     communications, and the Apache web server to provide
     repository-side network service.  This gives Subversion an
     advantage over CVS in interoperability, and provides various key
     features for free: authentication, path-based authorization, wire
     compression, and basic repository browsing. </p>
 </li>

 <li><strong>Standalone server option.</strong>
     <p>Subversion also offers a standalone server option using a
     custom protocol (not everyone wants to run Apache 2.x).  The
     standalone server can run as an inetd service, or in daemon mode,
     and offers basic authentication and authorization.  It can also be
     tunnelled over ssh.</p>
 </li>

 <li><strong>Branching and tagging are cheap (constant time) operations</strong>
     <p>There is no reason for these operations to be expensive, so
     they aren't.</p>

     <p>Branches and tags are both implemented in terms of an
     underlying "copy" operation.  A copy takes up a small, constant
     amount of space.  Any copy is a tag; and if you start committing
     on a copy, then it's a branch as well.  (This does away with CVS's
     "branch-point tagging", by removing the distinction that made
     branch-point tags necessary in the first place.)</p>
 </li>

 <li><strong>Natively client/server, layered library design</strong>
     <p> Subversion is designed to be client/server from the beginning;
     thus avoiding some of the maintenance problems which have plagued
     CVS.  The code is structured as a set of modules with well-defined
     interfaces, designed to be called by other applications.</p>
 </li>

 <li><strong>Client/server protocol sends diffs in both directions</strong>
     <p>The network protocol uses bandwidth efficiently by transmitting
     diffs in both directions whenever possible (CVS sends diffs from
     server to client, but not client to server).</p>
 </li>

 <li><strong>Costs are proportional to change size, not data size</strong>
     <p>In general, the time required for a Subversion operation is
     proportional to the size of the <i>changes</i> resulting from that
     operation, not to the absolute size of the project in which the
     changes are taking place.  This is a property of the Subversion
     repository model.</p>
 </li>


 <li><strong>Choice of database or plain-file repository implementations</strong>
   <p>Repositories can be created with either an embedded database
      back-end (BerkeleyDB) or with normal flat-file back-end, which
      uses a custom format.</p>
 </li>

 <li><strong>Versioning of symbolic links</strong>
   <p>Unix users can place symbolic links under version control.  The
      links are recreated in Unix working copies, but not in win32
      working copies.</p>
 </li>

 <li><strong>Efficient handling of binary files</strong>
     <p>Subversion is equally efficient on binary as on text files,
     because it uses a binary diffing algorithm to transmit and store
     successive revisions.</p>
 </li>

 <li><strong>Parseable output</strong>
     <p>All output of the Subversion command-line client is carefully
     designed to be both human readable and automatically parseable;
     scriptability is a high priority.
 </p>
 </li>

 <li><strong>Localized messages</strong>
   <p>Subversion uses gettext() to display translated error,
      informational, and help messages, based on current locale
      settings.</p>
 </li>

 </ul>

 <p>
 <h2>Future Subversion Features</h2>
 <p>

 <p>See the <a href="roadmap.html">Roadmap</a> page.</p>


 <br>
 </table>

 </div>
 </body>
 </html>
	<html>
	<head>
	<title>subversion.tigris.org</title>
	<link rel="stylesheet" type="text/css"
	href="http://subversion.tigris.org/branding/css/tigris.css"/>
	<link rel="stylesheet" type="text/css"
	href="http://subversion.tigris.org/branding/css/inst.css"/>
	<link rel="stylesheet" type="text/css" media="print"
	href="http://subversion.tigris.org/branding/css/print.css"/>
	<script type="text/javascript"
	src="http://subversion.tigris.org/branding/scripts/tigris.js"></script>
	</head>

	<body>
	<div class="app">

	<table border="0" cellpadding="2" width="98%" bgcolor="white">
	<tr>
	<td width="100%" bgcolor="yellow">
	<font color="red">
	<b>
	If you're using Subversion, we recommend that you join the <a
	href="/servlets/ProjectMailingListList">users@subversion.tigris.org</a>
	mailing list, and read the <a
	href="http://svnbook.red-bean.com/">Subversion Book</a> and <a
	href="/faq.html">FAQ</a>. You can also ask questions on IRC
	at <tt><a href="irc://irc.freenode.net/">irc.freenode.net</a></tt>,
	channel <tt><a href="irc://irc.freenode.net/svn">#svn</a></tt>.
	</b>
	</font>
	</td>
	</tr>

	</table>

	<h3>What Is Subversion?</h3>

	<table border="0" cellpadding="2" width="98%" bgcolor="white">
	<tr>
	<td width="100%" height="100" bgcolor="#f0f0f0">

	<p>
	The goal of the Subversion project is to build a version control
	system that is a compelling replacement for CVS in the open source
	community. The software is released under an <a
	href="/project_license.html">Apache/BSD-style</a> open source license.
	</p>

	<p>
	<center>
	<img src="/subversion_logo_hor-468x64.png" alt="Subversion"
	width="468" height="64" align="center"/>
	</center>
	</p>

	<p>
	<h2>Subversion's Features</h2>
	<p>

	<ul> <!-- list of features -->

	<li><strong>Most current CVS features.</strong>
	<p>Subversion is meant to be a better CVS, so it has most of
	CVS's features. Generally, Subversion's interface to a particular
	feature is similar to CVS's, except where there's a compelling
	reason to do otherwise.</p>
	</li>

	<li><strong>Directories, renames, and file meta-data are versioned.</strong>
	<p>Lack of these features is one of the most common complaints
	against CVS. Subversion versions not only file contents and file
	existence, but also directories, copies, and renames. It also
	allows arbitrary metadata ("properties") to be versioned along
	with any file or directory, and provides a mechanism for
	versioning the `execute' permission flag on files.
	</p>
	</li>

	<li><strong>Commits are truly atomic.</strong>
	<p>No part of a commit takes effect until the entire commit has
	succeeded. Revision numbers are per-commit, not per-file; log
	messages are attached to the revision, not stored redundantly as
	in CVS.</p>
	</li>

	<li><strong>Apache network server option, with WebDAV/DeltaV
	protocol.</strong>
	<p>Subversion can use the HTTP-based WebDAV/DeltaV protocol for network
	communications, and the Apache web server to provide
	repository-side network service. This gives Subversion an
	advantage over CVS in interoperability, and provides various key
	features for free: authentication, path-based authorization, wire
	compression, and basic repository browsing. </p>
	</li>

	<li><strong>Standalone server option.</strong>
	<p>Subversion also offers a standalone server option using a
	custom protocol (not everyone wants to run Apache 2.x). The
	standalone server can run as an inetd service, or in daemon mode,
	and offers basic authentication and authorization. It can also be
	tunnelled over ssh.</p>
	</li>

	<li><strong>Branching and tagging are cheap (constant time) operations</strong>
	<p>There is no reason for these operations to be expensive, so
	they aren't.</p>

	<p>Branches and tags are both implemented in terms of an
	underlying "copy" operation. A copy takes up a small, constant
	amount of space. Any copy is a tag; and if you start committing
	on a copy, then it's a branch as well. (This does away with CVS's
	"branch-point tagging", by removing the distinction that made
	branch-point tags necessary in the first place.)</p>
	</li>

	<li><strong>Natively client/server, layered library design</strong>
	<p> Subversion is designed to be client/server from the beginning;
	thus avoiding some of the maintenance problems which have plagued
	CVS. The code is structured as a set of modules with well-defined
	interfaces, designed to be called by other applications.</p>
	</li>

	<li><strong>Client/server protocol sends diffs in both directions</strong>
	<p>The network protocol uses bandwidth efficiently by transmitting
	diffs in both directions whenever possible (CVS sends diffs from
	server to client, but not client to server).</p>
	</li>

	<li><strong>Costs are proportional to change size, not data size</strong>
	<p>In general, the time required for a Subversion operation is
	proportional to the size of the <i>changes</i> resulting from that
	operation, not to the absolute size of the project in which the
	changes are taking place. This is a property of the Subversion
	repository model.</p>
	</li>


	<li><strong>Choice of database or plain-file repository implementations</strong>
	<p>Repositories can be created with either an embedded database
	back-end (BerkeleyDB) or with normal flat-file back-end, which
	uses a custom format.</p>
	</li>

	<li><strong>Versioning of symbolic links</strong>
	<p>Unix users can place symbolic links under version control. The
	links are recreated in Unix working copies, but not in win32
	working copies.</p>
	</li>

	<li><strong>Efficient handling of binary files</strong>
	<p>Subversion is equally efficient on binary as on text files,
	because it uses a binary diffing algorithm to transmit and store
	successive revisions.</p>
	</li>

	<li><strong>Parseable output</strong>
	<p>All output of the Subversion command-line client is carefully
	designed to be both human readable and automatically parseable;
	scriptability is a high priority.
	</p>
	</li>

	<li><strong>Localized messages</strong>
	<p>Subversion uses gettext() to display translated error,
	informational, and help messages, based on current locale
	settings.</p>
	</li>

	</ul>

	<p>
	<h2>Future Subversion Features</h2>
	<p>

	<p>See the <a href="roadmap.html">Roadmap</a> page.</p>


	<br>
	</table>

	</div>
	</body>
	</html>