\chapter{Online Software}

\section{PVSS}


\section{Feeserver and Control Engine}

\subsection{Patch Maker}

\section{Shuttle}

\emph{Disclaimer: This section was written By T Dietel in an attempt
  to summarize the status quo of the TRD shuttle. The main
  contributions to this software were done by F Kramer, T Bird and H
  Beck (according to git and svn log). Any inaccuracies should be
  (blamed on and) reported to T Dietel.}\vspace{2em}

The TRD Shuttle is actually a bridge between the DCS and the Offline
world, and could be described in both places. It consists of several
components:
\begin{itemize}
\item The \textbf{fxsproxy} collects information from the FEE, the
  pretrigger system and the GTU, formats the information as a single
  XML document and passes it on to the file exchange server
  (FXS)/shuttle that transfers the data from the DCS network into the
  offline world.
\item The \textbf{AliTRDSaxHandler} validates and processes the XML
  document from the fxsproxy and generates an AliTRDCalDCSv2 object
  that contains all the data.
\item The \textbf{AliTRDPreprocessor} reads the information from the
  fxsproxy (and other sources), relying on the AliTRDSaxHandler for
  the heavy-lifting.
\item The class \textbf{AliTRDCalDCSv2} will be stored in the OCDB and
  contains all the configuration information for a given run.
\end{itemize}

\subsection{FXS Proxy}

The fxsproxy is a small daemon that runs on one of the Linux
workernodes in the DCS network (alitrdwn009 at the point of writing).
It waits for the command to collect the start-of-run (SOR) or
end-of-run (EOR) configuration of the TRD, which will usually come
from WinCC via DIM. The fxsproxy then queries the front-end
electronics (FEE), the Global Tracking Unit (GTU) and the pretrigger
system (PTR). It collects their configurations, formats them as a
single XML document, writes one copy of th document to local disk
(under \texttt{/data/fxsproxy\underline{ }output\underline{ }files}),
and places one copy on the file exchange server in the DCS network.

The files under \texttt{/data/fxsproxy\underline{ }output\underline{
  }files} can be usefule for debugging, as they contain a lot (all?)
information about the configuration of the TRD. As XML, they can be
viewed with a normal pager/text editor. There is also a XSL stylesheet
to display the fxsproxy files in a browser, but I don't know how to
use it.

The fxsproxy would be a natural place to verify the configuration of
the TRD and check for inconsistencies, such as different FEE
configurations or gain tables for different chambers, or the
consistency between GTU/PTR and FEE settings. 


