svn commit: r1390487 - /subversion/trunk/subversion/include/svn_dav.h

[cm...@apache.org]

Author: cmpilato
Date: Wed Sep 26 13:56:20 2012
New Revision: 1390487

URL: http://svn.apache.org/viewvc?rev=1390487&view=rev
Log:
* subversion/include/svn_dav.h
  (SVN_DAV_DELTA_BASE_HEADER): Add a @note to the docstring which
    carries historical information behind this header's purpose and use.

Modified:
    subversion/trunk/subversion/include/svn_dav.h

Modified: subversion/trunk/subversion/include/svn_dav.h
URL: http://svn.apache.org/viewvc/subversion/trunk/subversion/include/svn_dav.h?rev=1390487&r1=1390486&r2=1390487&view=diff
==============================================================================
--- subversion/trunk/subversion/include/svn_dav.h (original)
+++ subversion/trunk/subversion/include/svn_dav.h Wed Sep 26 13:56:20 2012
@@ -53,6 +53,15 @@ extern "C" {
 
 /** This header is *TEMPORARILY* used to transmit the delta base to the
  * server. It contains a version resource URL for what is on the client.
+ *
+ * @note The HTTP delta draft recommends an If-None-Match header
+ * holding an entity tag corresponding to the base copy that the
+ * client has.  In Subversion, it is much more natural to use a version
+ * URL to specify that base.  We'd like, then, to use the If: header
+ * to specify the URL.  Unfortunately, mod_dav sees all "State-token"
+ * items as lock tokens.  So we'll use this custom header until mod_dav
+ * and other backend APIs are taught to be less rigid, at which time
+ * we can switch to using an If: header to report our base version.
  */
 #define SVN_DAV_DELTA_BASE_HEADER "X-SVN-VR-Base"