svn commit: r1399270 - /subversion/site/publish/docs/release-notes/1.8.html

[cmpilato]

Author: cmpilato
Date: Wed Oct 17 14:00:13 2012
New Revision: 1399270

URL: http://svn.apache.org/viewvc?rev=1399270&view=rev
Log:
Document SVNMasterVersion in the 1.8 release notes.

* site/publish/docs/release-notes/1.8.html
  (#svnmasterversion): New section describing the SVNMasterVersion
    directive (and replacing the TODO which was left to remind us to
    write this section.)

Modified:
    subversion/site/publish/docs/release-notes/1.8.html

Modified: subversion/site/publish/docs/release-notes/1.8.html
URL: 
http://svn.apache.org/viewvc/subversion/site/publish/docs/release-notes/1.8.html?rev=1399270&r1=1399269&r2=1399270&view=diff
==============================================================================
--- subversion/site/publish/docs/release-notes/1.8.html (original)
+++ subversion/site/publish/docs/release-notes/1.8.html Wed Oct 17 14:00:13 2012
@@ -1429,7 +1429,60 @@ rel="nofollow">Paul Querna</a> for the <
 
 </div>  <!-- svnpubsub -->
 
-<p class="todo">TODO: document SVNMasterVersion</p>
+<div class="h3" id="svnmasterversion">
+<h3>New <tt>SVNMasterVersion</tt> Apache HTTP Server configuration directive
+  <a class="sectionlink" href="#svnmasterversion"
+    title="Link to this section">&para;</a>
+</h3>
+
+<p>Subversion's HTTP protocol continues to mature and expand over time
+to support new features or better ways to accomplish things.
+Fortunately, Subversion servers and clients happily negotiate which
+bits of that protocol they both understand.  Unfortunately, WebDAV
+proxy configurations can throw this negotiation for a loop, as the
+slave server does the negotiating but not necessarily all the
+operating.  Thus, a Subversion 1.7 WebDAV proxy slave will by default
+tell the client that it's okay to use the <a href="./1.7.html#httpv2"
+>HTTPv2 protocol</a>, and a Subversion 1.7 or better client will do
+so, even if the <em>master</em> server behind the proxy is running
+Subversion 1.6 and unable to understand the new protocol.</p>
+
+<p>When Subversion 1.7 was released, this specific problem was
+addressed by providing an Apache HTTP Server configuration
+directive &mdash; <tt>SVNAdvertiseV2Protocol</tt> &mdash; which allowed
+administrators in such a scenario to "dumb down" the communications of
+the Subversion 1.7 slave server so that connecting clients would use
+the older protocol and, in doing so, not confuse the Subversion 1.6
+master server when requests were proxied to it.  As development
+continued toward 1.8, though, there where several new features and
+protocol changes made which would likewise require a toggle switch
+to avoid confusing pre-1.8 WebDAV proxy master servers.</p>
+
+<p>Rather than exposing a suite of such toggles &mdash; some of which
+were for behaviors that are entirely specific to the protocol itself
+and not tied to any user-visible feature &mdash; Subversion 1.8 allows
+administrators to simply declare to the slave servers the version of
+Subversion which is powering the master server, allowing the slave
+servers to enable and disable features as makes sense for that
+scenario.  Administrators of Subversion deployments which use the
+WebDAV write-through proxy feature are strongly encouraged to use the
+new <tt>SVNMasterVersion</tt> httpd.conf directive in all slave server
+configurations running Subversion 1.8 or better.</p>
+
+<p>For example, if your master server is running Subversion 1.7.7, your
+Subversion 1.8 slave server's Apache HTTP Server configuration might
+contain something like this:</p>
+
+<pre>&lt;Location /svn&gt;
+DAV svn
+&hellip;
+SVNMasterURI http://master.svn.company.com/svn
+SVNMasterVersion 1.7.7
+&hellip;
+&lt;/Location&gt;
+</pre>
+
+</div>  <!-- svnmasterversion -->
 
 </div>  <!-- enhancements -->