\chapter{Running NoTA}\label{chap:running}\index{running}

After all the programming, you might actually want to run you NoTA-based

program. It is not very hard, but there some things to keep in mind.

\section{First steps}

The two important questions to answer are:

\begin{itemize}

\item which ones of my nodes have \emph{single-process} capabilities, and which not?

\item which node should become the \emph{manager node}?

\end{itemize}

\subsection{Single-process or not?}

In appendix~\ref{chap:building} we discussed the building of single-process

and non-single-process nodes. It's important to know if we any nodes that are

\textbf{not} single-process capable, you \textbf{have to} run the NoTA daemon,

\textbf{nota-ind}.

If you have received some binary ('\texttt{mynode}') , and don't \emph{know} if

it supports single-process-capabilities or not, you can of course try. Or

you can inspect the libraries '\texttt{mynode}' is linked against:

\begin{verbatim}

  $ ldd myprogram                                                                                       ~

	linux-gate.so.1 =>  (0xb7fb0000)

	libh_in3_sp.so.0 => /usr/lib/libh_in3_sp.so.0 (0xb7f80000)

        [ .... ]

\end{verbatim}

As you see \texttt{libh\_in3\_sp.*} in the linked libraries, you know the

program has single-process capabilities. If it didn't you would have found

\texttt{libh\_in3.*}. In practice, it's a good convention to put \texttt{-sp}

somewhere in the binary name of nodes that support single-process mode.

Once more: if at least one of your nodes does not have single process

capabilities, you will need to start the NoTA daemon (read on for details).

\subsection{Electing a manager}

In any NoTA system there has to be at least one node with \emph{manager

  capabilities}\index{manager node} - we call this node the \textbf{manager

  ndde}. This node has some special responsibilities regarding an accurate

view of the network -- that is, it maintains a list of active nodes in the

network, and where to find them. This should be confused with the Resource

Manager - the manager node works at an architecturally lower lever. 

\subsubsection{Not all managers are daemons}

If your system, as explained before, not use the NoTA daemon, you can elect a

manager by starting one of the (service) nodes with the special environment

variable \texttt{NOTA\_LMANAGER}\index{\texttt{NOTA\_LMANAGER}}. If it is set

to \texttt{1}, the node finds out about its role and will dutifully take on

the corresponding reponsibilities. So:

\begin{verbatim}

  $ NOTA_LMANAGER=1 my-node

\end{verbatim}

will make \textbf{my-node} the manager node.

\subsubsection{Daemons can be managers too}

If your system is using

\texttt{nota-ind}\index{\texttt{nota-ind}}\index{daemon}, this is a natural

choice to become the manager node. You can run start

\texttt{nota-ind}\index{\texttt{nota-ind}} in manager-mode with the

\textbf{-m} option:

\begin{verbatim}

  $ nota-ind -m

\end{verbatim}

In some cases, you might even want to run multiple daemons of which of course

only one can be the manager. 

\subsection{The resource manager}

In many of the simpler examples, we don't use the Resource

Manager\index{resource manager}(RM). As explained in chapter~\ref{chap:rm},

that is not a very scalable solution, and in bigger systems we \textbf{do}

want to use the RM.

After you've installed NoTA (if needed, see appendix~\ref{chap:installing}),

the resource manager will be available as a program called

\texttt{nota-rmsvc}\index{\texttt{nota-rmsvc}}. Note that the resource manager

does \textbf{not} run in single-process mode; thus, running the resource

manager also implies running \texttt{nota-ind}.

When you start \texttt{nota-rmsvc}, you are greeted with a little menu:

\begin{verbatim}

 $ nota-rmsvc

 [...]

 1: print service_list

 2: print eventreq_list

 8: initialize service_list

 9: clear eventreq_list

 x: exit

 [1-2, 8-9, x] > 

\end{verbatim}

Options 1 and 2 allow you to inspect the list of services and events. Options

8 and 9 can be used to clear them. The latter is of course not recommend to keep

your NoTA-system well-functioning, but it can be useful for debugging.

\section{Running}

After all these decisions, we can start our system. You can follow the

following steps:

\begin{enumerate}

  \item If your system needs \texttt{nota-ind}, start it; in most cases,

    you'd use \texttt{nota-ind -m}, to start the NoTA daemon in manager mode;

  \item If your systems needs the Resource Manager, start

    \texttt{nota-rmsvc}. If you hadn't started \texttt{nota-ind} yet, the

    Resource Manager will not start; go back to step 1 in that case;

  \item start your Service Nodes (SNs);

  \item start your Application nodes (ANs);

  \item sit back an watch your system perform beyond expectations.

\end{enumerate}