Вы можете использовать matlab.net.http
header = [matlab.net.http.field.AcceptField(matlab.net.http.MediaType('application/json'))...
matlab.net.http.field.ContentTypeField('text/plain');];
body = jsonencode(data);
request = matlab.net.http.RequestMessage(matlab.net.http.RequestMethod.POST,...
header,...
body);
response = send(request, self.address);
result = response.Body.Data;