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Revision 1.2, Sun Jan 2 07:32:12 2000 UTC (24 years, 4 months ago) by takayama
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A rough draft of our paper on OpenXM for ISSAC2000.
I will print it today and make a minor changes.
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% $OpenXM: OpenXM/doc/issac2000/openxm-stackmachines.tex,v 1.2 2000/01/02 07:32:12 takayama Exp $
\section{OpenXM Stackmachines} (Tamura)
In OpenXM specification, all servers are stackmachines.
These are called OpenXM stachmachines.
When a server ox\_xyz gets a OX data message,
it translates the data into its own object and push the object
on the stack.
The translation scheme together with mathematical operation definitions
of the system ox\_xyz is called the {\it phrase dictionary} of
ox\_xyz following the idea of OpenMath.
OX command message starts with the int32 tag OX\_COMMAND.
The body is OpenXM stackmachine operation code expressed by int32.
The codes are listed below.
\begin{verbatim}
#define SM_popSerializedLocalObject 258
#define SM_popCMO 262
#define SM_popString 263
#define SM_mathcap 264
#define SM_pops 265
#define SM_setName 266
#define SM_evalName 267
#define SM_executeStringByLocalParser 268
#define SM_executeFunction 269
#define SM_beginBlock 270
#define SM_endBlock 271
#define SM_shutdown 272
#define SM_setMathCap 273
#define SM_executeStringByLocalParserInBatchMode 274
#define SM_getsp 275
#define SM_dupErrors 276
#define SM_DUMMY_sendcmo 280
#define SM_sync_ball 281
#define SM_control_kill 1024
#define SM_control_to_debug_mode 1025
#define SM_control_exit_debug_mode 1026
#define SM_control_reset_connection 1030
\end{verbatim}
OpenXM does not have a standard for mathematical operation sets
while it is one of the main future projects of \cite{gap}.
Each OpenXM server has its own mathematical operation set.
Mathematical operator name, such as fctr (asir factorization command),
is pushed as a string,
SM\_executeFunction pops the operator name, the number of arguments
and arguments,
evaluates the operator, and pushes the result on the stack.
For example, the following code factorizes $x^{100}-1$ by calling
ox\_asir.
\begin{verbatim}
P = ox_launch();
ox_push_cmo(P,x^100-1); ox_push_cmo(P,ox_int32(1));
ox_push_cmd(P,269);
Ans = ox_pop_cmo(P);
\end{verbatim}
When an error has occurred on an OpenXM server,
an error object is pushed to the stack instead of a result of the computation.
The error object consists of the serial number of the OX message
which caused the error, and an error message.
\begin{verbatim}
[341] ox_rpc(0,"fctr",1.2*x)$
[342] ox_pop_cmo(0);
error([8,fctr : invalid argument])
\end{verbatim}
Errors are not sent to the client except a SM\_pop* command is received.
Open XM stackmachines works in the asynchoronous mode which is similar
to X servers.
For servers of graphic applications, it is an advantageous feature.
It is also easy to emulate RPC and a web server for MCP \cite{iamc}
on our OpenXM stackmachines.