We've got VisualSVN Server set up as our Subversion server on Windows, and we use Ankhsvn + TortoiseSVN as clients on our workstations.
How can you configure the server to require commit messages to be non-empty?
I'm glad you asked this question. This is our pre-commit hook script written in common Windows Batch. It denies commit if the log message is less than 6 characters. Just put the pre-commit.bat to your hooks directory.
pre-commit.bat
setlocal enabledelayedexpansion
set REPOS=%1
set TXN=%2
set SVNLOOK="%VISUALSVN_SERVER%\bin\svnlook.exe"
SET M=
REM Concatenate all the lines in the commit message
FOR /F "usebackq delims==" %%g IN (`%SVNLOOK% log -t %TXN% %REPOS%`) DO SET M=!M!%%g
REM Make sure M is defined
SET M=0%M%
REM Here the 6 is the length we require
IF NOT "%M:~6,1%"=="" goto NORMAL_EXIT
:ERROR_TOO_SHORT
echo "Commit note must be at least 6 letters" >&2
goto ERROR_EXIT
:ERROR_EXIT
exit /b 1
REM All checks passed, so allow the commit.
:NORMAL_EXIT
exit 0