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Reasonably complete and up-to-date docs.

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doc/latex/nettime.tex
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\chapter{Using Time and Daytime Protocol}\label{cha:ntp} \chapter{Time and Daytime}\label{cha:ntp}
%
\begin{description}
\item[Used files:] nettime.scm nettime-obsolete.scm
\item[Name of the package:] nettime nettime-obsolete
\end{description}
%
\subsection{Overview} Many Unix hosts provide a RFC~867 Daytime service which sends the
Most Unix hosts provide a Daytime service which sends the current date current date and time as a human-readable character string. The
and time as a human-readable character string. The daytime service is daytime service is typically served on port 13 as both TCP and UDP.
typically served on port 13 as both TCP and UDP.
The Time protocol provides a site-independent, machine readable date The RFC~868 Time protocol provides a site-independent, machine
and time. A ``time'' consists of the number of seconds since midnight on readable date and time. The Time service is typically served
1st January 1900. The Time service is typically served on port 37 as on port 37 as TCP and UDP. The idea is that you can confirm your
TCP and UDP. The idea is that you can confirm your system's idea of system's idea of the time by polling several independent sites on the
the time by polling several independent sites on the network. network.
\subsection{Procedures} \section{Daytime}
\begin{defundesc}{net-time}{host tcp/udp}{integer} The \ex{rfc867} structure contains an interface to Daytime protocol.
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). 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} \defun{rfc867-daytime/tcp}{host}{string}
Asks \semvar{host} about the current daytime. \semvar{tcp/udp} is \defunx{rfc867-daytime/udp}{host [timeout-or-\sharpf]}{string-or-\sharpf}
the same as in \ex{net:time}, indicating to use TCP or UDP. The \begin{desc}
host's answer is returned (e.g., ``Thursday, April 4, 2''). These procedures asks \var{host} about the current daytime and
\end{defundesc} return the host's answer (e.g., ``Thursday, April 4,
2'').
\subsubsection*{Obsolete procedures} \ex{Rfc867-daytime/tcp} uses the TCP variant of the protocol.
\ex{Rfc867-daytime/udp} uses UDP and sends a single request to the
server. It allows the specification of an optional timeout; if not
specified or \sharpf{}, \ex{Rfc867-daytime/udp} will wait
indefinitely for an answer. If the answer from the server doesn't
arrive within the specified time, \ex{rfc867-daytime/udp} returns
\sharpf.
\end{desc}
Names in further versions of \ex{nettime} contained a colon (`\ex{:}') \section{Time}
after the prefix `\ex{net-}'. This is now changed to a hyphen
('\ex{-}'), accordingly to SUnet's philosophy. If you need the old The \ex{rfc868} structure contains an interface to the Time protocol.
names, use the \ex{nettime\=obsolete}-package that maps the old names
to the new ones. \defun{rfc868-time/tcp}{host}{string}
\defunx{rfc868-time/udp}{host [timeout-or-\sharpf]}{string-or-\sharpf}
\begin{desc}
These procedures asks \var{host} about the current time and return
the host's answer. This is the number of second since 1970, just as
with scsh's \texttt{time} procedure.
\ex{rfc868-time/tcp} uses the TCP variant of the protocol.
\ex{rfc868-time/udp} uses UDP and sends a single request to the
server. It allows the specification of an optional timeout; if not
specified or \sharpf{}, \ex{rfc868-time/udp} will wait
indefinitely for an answer. If the answer from the server doesn't
arrive within the specified time, \ex{rfc868-time/udp} returns
\sharpf.
\end{desc}
\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: %%% Local Variables:
%%% mode: latex %%% mode: latex