Force Closing HTTP Connection

I have written the function below to communicate over HTTP. It works but MATLAB appears to be holding the connection open. I have another application (non-MATLAB) that I also use to communicate separately. Once I call this function for the first time, the other application stops working until I close MATLAB. I've dug around but I can't figure out how to make MATLAB give up the connection. MATLAB states that the connection is not persistent but my experience seems to indicate otherwise. Is there a way to force a disconnect?

function response = sendRequest(URL,JSON_Message)

uri= matlab.net.URI(URL);

request=matlab.net.http.RequestMessage;
request.Method = 'POST';
request.Body =JSON_Message;

% matlab.net.http.HTTPOptions persists across requests to reuse  previous
persistent options 

if isempty(options)
    options = matlab.net.http.HTTPOptions('Authenticate',false,'KeepAliveTimeout',0,'ConnectTimeout',10,'ResponseTimeout',60, ...
        'UseProgressMonitor',false,'UseProxy',false,'VerifyServerName',false,'DataTimeout',60,'MaxRedirects',0);
end

% Send request and get response and history of transaction.
[data, ~, history] = request.send(uri, options);

response = data.Body.Data;

end

[Walter Roberson]

There are two possibilities here:

First off, the connection might be stuck somewhere in the MATLAB implementing code. I do not know if it is possible to get it unstuck in this case. Quite possibly not.

Secondly, the connection might be stuck in the network stack, such as if the network stack is waiting for a missing ACK. The only way to get it unstuck in this circumstance is to shoot the process -- and even that is not certain.

[dpb]

I think this issue deserves an official bug/support request.

Answer 1

[Shivam]

Hi Jay,

I get that while establising the HTTP connection with the parameter 'KeepAliveTimeout' set to 0, the connection doesn't get closed after first connection with the server.

As a workaround, you can explicitly set the 'Connection' header to 'close'.

Please refer to the modified function to close the connection after response is sent:

function response = sendRequest(URL,JSON_Message)

    %
    % ..
    %

    % Set the Connection header to 'close' to ensure the connection is not kept alive
    request.Header = matlab.net.http.field.GenericField('Connection', 'close');
    

    %
    % ...
    %
    
    % Check the Connection header in the response
    connectionHeader = data.Header.getFields('Connection');
    if ~isempty(connectionHeader)
        disp(['Connection header in response: ', connectionHeader.Value]); % connectionHeader.Value is "close" if the connection gets closed
    else
        disp('No Connection header found in response.');
    end

end

I hope it helps in resolving the issue.

Thanks and Regards,

Shivam

[Jay Anselm]

Shivam,

Thank you! This made it work.

Much appreciated,

Jay