listen

advertisement
You can talk to octave directly from other environments over the tcp/ip.
The protocol is not sophisticated.
Here is what you can send to octave:
!!!x length command
evaluate command in octave.
length is a 32-bit network order integer.
command is a string (without zero-terminator).
!!!m length name
send matrix back to client.
length is a 32-bit network order integer.
name is a string (without zero-terminator).
I don't use the !!!m command to the server because it is the same
as
!!!x send('name', matrix expression)
The latter is much more useful because you don't have to name
the data that you are sending across.
!!!n length namelen name command
*** Not implemented ***
Evaluate the command in the namespace. This needs a lookup table
Map<string,symbol_table> namespace
and a command
evalin(symbol_table,command)
The function evalin pushes the given symbol table onto
curr_sym_tab,
evaluates the command then pops the symbol table.
Here is what you will receive from octave:
!!!m length rows columns namelength name data
recieve matrix from server.
length,rows,columns,namelength are 32-bit network order integers.
name is a string (without zero-terminator).
data is an array of rows*columns server order double values.
This is sent in response to a !!!m matrix request or a
send('name',matrix) command.
The first thing I do when I open a connection is request a matrix
containing 1.0. If the result is not 1.0, I know that I need to
swap the data to convert from server order to client order doubles.
!!!s length strlen namelen name str
receive string from server.
length, strlen, namelen are 32-bit network order integers.
name is a string (without zero-terminator).
str is a string (without zero-terminator).
This is sent in response to a send('name',string) command.
!!!x length str
evaluate string in client.
length is a 32-bit network order integer.
str is a string (without zero-terminator).
This is sent in response to a send('str'). The contents of str
are completely arbitrary (and may indeed contain binary data). It
is
up to the client to decide how they want to interpret these
strings.
!!!e length error
receive error from octave.
length is a 32-bit network order integer.
error is a string (without zero-terminator).
This is sent in response to a !!!x command which produced an error.
Composite values can be decomposed into their constituent parts. E.g.,
structures:
for [v,k]=x, send([name,'.',k],v); end
complex arrays:
send([name,'.real'],real(x));
send([name,'.imag'],imag(x));
sparse arrays:
[v,i,j] = spfind(x);
send([name,'.i'],i);
send([name,'.j'],j);
send([name,'.v'],v);
cell arrays:
[nr,nc]=size(x);
for r=1:nr, for c=1:nc, send([name,sprintf('.%d.%d',r,c)],x{r,c});
end
Note that the communication is completely asynchronous. I have a tcl
client
that processes server responses via fileevent. That means that responses
from
octave are not processed until tcl enters its event loop.
To be sure that octave has processed a command I follow that command with
a
synchronization sequence:
set sync[incr syncid] 1
octave eval "send('unset sync$syncid')"
vwait sync$syncid
In practice it is more complicated than that because I allow the
syncronization command to time out just in case octave crashed out from
underneath me, but the idea is the same.
Using sockets gives you platform independence and network transparency,
which is a big win. The only caveat is that winsock is slow. The best I
can do with dedicated winsock code on my machine is .3 seconds to
transfer
a 1 Mb message. Under tcl/tk, it was closer to 1 second IIRC. A memory
copy of the same size took less than 0.06 seconds IIRC.
That is why I'm working on a way to embed octave into tcl.
it will be easy to embed in other environments as well.
Paul Kienzle
2003
Hopefully
Download
Random flashcards
Arab people

15 Cards

Ethnology

14 Cards

Create flashcards