% $OpenXM: OpenXM/doc/issac2000/openxm-clients.tex,v 1.8 2000/01/16 10:58:19 takayama Exp $

\section{OpenXM Clients}    

\subsection{Risa/Asir}

Risa/Asir provides a launcher to invoke an OpenXM server and to set up the
communication between the server and itself. As a client, 
it provides many built-in functions for communication.

\subsubsection{Setting up servers}
{\tt ox\_launch} is a general purpose launcher.  This application
invokes a server and sets up the server-client communication
according to the protocol stated in Section \ref{launcher}, then
itself becomes a control server.
Several facilities related to {{\tt ox\_launch}} are provided
as built-in functions of Risa/Asir: a function to invoke a server
automatically from a give host name and a server name, and a set 
of functions to execute the port generation, {\tt bind}, {\tt listen},
{\tt connect} and {\tt accept} operations on sockets individually.

\subsubsection{Manipulating servers}
Fundamental operations on OpenXM servers are 
exchange of {\tt OX} data and sending of {\tt SM} commands.
The following functions
are provided to execute these primitive operations:
{\tt ox\_push\_cmo()} for pushing data to a server, 
{\tt ox\_push\_cmd()} for sending an {\tt SM} command to a server
and {\tt ox\_get()} for receiving data from a stream.

Some operations including the reset operation are realized by
combining these primitives.  Among them, frequently used ones are
provided as built-in functions. We show several ones.

\begin{itemize}
\item {\tt ox\_pop\_cmo()}

It requests a server to send data on the stack to the stream, then
it receives the data from the stream.

\item {\tt ox\_cmo\_rpc()}

After pushing the name of a function, arguments and the number of the
arguments to the stack of a server, it requests the server to execute
the function. It does not wait the termination of the function call.

\item {\tt ox\_reset()}

After sending {\tt SM\_control\_reset\_connection} to a control server,
it completes the operations stated in Section \ref{control}.
\end{itemize}
Furthermore {\tt ox\_select()} is provided to detect streams ready for
reading. It is realized by the {\tt select()} system call and is used
to avoid blocking on read operations.

\subsection{Mathematica}

We provide an OpenXM client {\tt math2ox} written as an external module
for Mathematica.  
The module {\tt math2ox} communicates with Mathematica by MathLink and
with any OpenXM server by the OpenXM protocol.  
By using the module {\tt math2ox},
we can call OpenXM servers from Mathematica;
here is a demonstration of a computation of the de Rham cohomology groups
of ${\bf C}^2 \setminus V(x^3-y^2)$ from Mathematica.
{\footnotesize
\begin{verbatim}
In[1]:= Install["math2ox"]
In[2]:= OxStart["../lib/sm1/bin/ox_sm1_forAsir"]
In[3]:= OxExecute[" [(x^3-y^2) (x,y)] deRham "]
In[4]:= OxPopString[]
Out[4]=  [ 1 , 1 , 0 ]  (* The dimension of 
                           cohomology groups *)
\end{verbatim}
}

The {\tt math2ox} adds the following functions to Mathematica.
\begin{quote}
{\tt OxStart[s\_String]} \\
{\tt OxStartInsecure[s\_String]} \\
{\tt OxExecuteString[s\_String]}  \\
{\tt OxParse[s\_String]} \\
{\tt OxGet[]} \\
{\tt OxPopCMO[]} \\
{\tt OxPopString[]} \\
{\tt OxClose[]} \\
{\tt OxReset[]}
\end{quote}
Although the list of functions speaks itself,
we add some explanations.
The function {\tt OxPopCMO[]} executes the same operation
as {\tt ox\_pop\_cmo()} in Risa/Asir;
it pops data from the server stack.
The {\tt OxGet[]} receives an OX data message
and returns its translation to an local object.
By using the {\tt OxParse[]} function, one can send OX messages,
written by the OX expression, to a server. 
OX expressions are Lisp-like expressions for OX messages and are defined
in~\cite{noro-takayama}.  
