Matlab socket is not interruptible?

Hi,

I am developing a Matlab UI/Socket program where users can click a button to start and read a tcp socket. It is obviously that such a design need the tcp socket not block the UI thread. I mainly reference a Matlab UI interruption guideline http://www.mathworks.com/help/matlab/creating_guis/callback-sequencing-and-interruption.html to build my program. Setting the 'Interruptible' flag to 'on' does achieve my expected behavior.

However, when I add the socket code into this "interruptible" callback, everything stop working. Here is the example code:

function create_update_waitbar
  h_wait = waitbar(0,'Please wait...',...
          'Position',[250,320,270,50],...
          'CloseRequestFcn',@close_waitbar);

        port = 50005;
        socket=tcpip('0.0.0.0', port, 'NetworkRole', 'server', 'Timeout', 60*60*24);    
        fprintf(2, '=== start wait connection to port = %d ===\n', port);
        fopen(socket);
        fprintf(2, '=== succeesfully get a connection to port = %d ===\n', port);

        for i=1:10000,
            if ishandle(h_wait)

            action=fread(socket, 1, 'int8')

            waitbar(i/10000,h_wait)
            tic
            fprintf('\nwait: %.1f: ', (i/10000)*100);
            toc
            else               
                break
            end
        end
        % When waitbar reaches max, close it.
        if ishandle(h_wait)        
           close(h_wait)
        end
    end

I basically just add a socket listening in the begin of the original callback function from the Matlab sample code and add a fread of that socket inside the waiting bar updating loop.

I expect the program can still let me use the UI (e.g., click the button to draw a figure as shown in the Matlab interruptible UI guideline), but it doesn't. This code will hang forever on the socket listening and socket read operations.

Any suggestion of achieving the goal of UI to control a Matlab socket?

Answer 1

[Prannay Jain]

Currently in MATLAB, when you try to open a connection (either as the 'server' or the 'client') using a 'tcpip' object, the call blocks MATLAB execution until either the connection is made or the call times out. In short, MATLAB tcpip socket is not interruptible.

I work for MathWorks and have provided this feedback to the developers.

[Yu-Chih Tung]

Thank you for confirming it. It is exactly what I expected. I have build a customized Java class to achieve the function I want.

Answer 2

[Prannay Jain]

'tcpip' is not a base MATLAB function. It comes with Instrument Control Toolbox. Can you try with 'tcpclient' which comes with base MATLAB to create tcp/ip socket?

http://www.mathworks.com/help/matlab/import_export/create-a-tcpip-connection.html

[Yu-Chih Tung]

Hi Prannay,

Just wanna let you know that I need the Matlab to be the server (not client). But your reply seems also useful to me in the future. I have built my customized Java server class (interfaced to Matlab) that can achieve listening/reading on a separate thread. I will attach the code after I clean it.

Answer 3

[Prannay Jain]

You have mentioned that setting the 'Interruptible' flag to 'on' does achieve your expected behavior. Then what is the part that you are not getting? Can you explain more on this?

I also want to confirm if you have Instrument Contol Toolbox license with your MATLAB.

[Yu-Chih Tung]

Hi Prannay,

I do have the license (from University of Michigan). The Interruptible flag does help to keep UI usable while having some processing on the callback, but this flag DON'T work if there is a tcpip socket operation in the callback.

Yu-Chih