include documentation on NETTIME-package

doc/latex/ntp.tex

@@ -5,4 +5,48 @@
 \item[Name of the package:] nettime
 \end{description}
 %
-Not implemented yet.
+
+\subsection{Overview}
+Most Unix hosts provide a Daytime service which sends the current date
+and time as a human-readable character string. The daytime service is
+typically served on port 13 as both TCP and UDP.
+
+The Time protocol provides a site-independent, machine readable date
+and time. A ``time'' consists of the number of seconds since midnight on
+1st January 1900. The Time service is typically served on port 37 as
+TCP and UDP. The idea is that you can confirm your system's idea of
+the time by polling several independent sites on the network.
+
+\subsection{Procedures}
+
+\begin{defundesc}{net:time}{host tcp/udp}{integer}
+  Asks \semvar{host} about the current time. \semvar{tcp/udp} is
+  either \ex{socket\=type/\ob{}stream} or
+  \ex{socket\=type/\ob{}datagram}, that indicate TCP or UDP
+  connection, respectively (depends on the server).\FIXME{Is it
+    correct, that the tcp/udp argument describes TCP or UDP use via
+    socket-type/stream or socket-type/datagram, resp.?} The number of
+  second since 1970 is returned, since the time protocol returns the
+  number of seconds since 1900, whereas Unix time is since 1970. The
+  difference between both answers is 2208988800.
+\end{defundesc}
+
+\begin{defundesc}{net:daytime}{host tcp/udp}{string}
+  Asks \semvar{host} about the current daytime. \semvar{tcp/udp} is
+  the same as in \ex{net:time}, indicating to use TCP or UDP. The
+  host's answer is returned (e.g., ``Thursday, April 4, 2'').
+\end{defundesc}
+
+\subsection{Related work}
+\begin{itemize}
+\item \ex{Time.pm} is a Perl module by Graham Barr
+\item RFC~868 describes the Time protocol
+\item RFC~867 describes the Daytime protocol in all its glory
+\item For a genuinely useful protocol look at the Network Time
+  Protocol defined in RFC~1305, which allows for the synchronization
+  of clocks on networked computers.
+\end{itemize}
+%%% Local Variables: 
+%%% mode: latex
+%%% TeX-master: t
+%%% End: