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\section*{Middleware}

\subsection*{DBUS}

Text

\subsection*{CORBA}

CORBA is a middleware, which allows RPC\footnote{Remote Procedure
  Call}-based IPC\footnote{Inter Process Communication} between
different operating systems and different programming languages
(Figure \ref{img:orb}).

The communication interfaces are defined in IDL\footnote{Interface Definition
  Language}. The IDL files are compiled into, e.g. c++, java, \dots,
code which does the (de)serialization of the datatypes. The interface
implementations (CORBA objects) are registered with language
specific ORB\footnote{Object Request Broker}s. Each CORBA process owns
one ORB, which handles the function requests and returns the
calculated values.

\begin{figure}
\centering
\includegraphics[width=0.8\textwidth]{images/orb.jpg}
\caption{Object Request Broker}
\label{img:orb}
\end{figure}

\begin{figure}
\centering
\includegraphics[width=0.8\textwidth]{images/rtcorbaext.jpg}
\caption{Real-time Object Request Broker (source: [1])}
\label{img:rtorb}
\end{figure}

As shown in figure \ref{img:rtorb}, a real-time capable ORB extends a standard 
ORB with the following features: locating objects in constant time,
preallocation of resources, operating system independent priority
handling, priority based scheduling.

ACE is an open-source c++ framework for platform-independent system-
and network-programming. TAO is a Real-time CORBA implementation build
on top of ACE (Figure \ref{img:ace}).

\begin{figure}
\centering
\includegraphics[width=0.8\textwidth]{images/ace.jpg}
\caption{ACE Framework (source: [2])}
\label{img:ace}
\end{figure}

The ACE/TAO package is available for all important operating
systems. The framework can be trimmed for embedded systems: Each
application described in this paper consumes less than 1 MByte of
RAM. Also the consumed CPU time is suprisingly low.

\subsection*{\"Ubungen}

\subsection*{Quellen}

\begin{thebibliography}{9}%use this if you have <=9 bib refs
%\begin{thebibliography}{99}%use this if you have >9 bib refs
\bibitem{paper1},{\it Real-time CORBA Specification},2005, {\sc OMG}
\bibitem{paper2},{\it Overview of ACE},2007\\{\it http://www.cs.wustl.edu/schmidt/ACE-overview.html}
\end{thebibliography}

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