specifying 'Timeout' in weboptions does not work

Hi all!

I want have a 1 sec. timeout in my call to webwrite(). However, this code takes 30 sec. to execute before throwing an error.

webwrite('http://dummy', 'blah', weboptions('Timeout', 1))

What is even more weird, is that the call to "weboptions" without arguments shows that the default is 5 sec. (returns "Timeout: 5")

I am running Matlab 2015a, on OS X 10.10

Any idea, what could be the problem?

Answer 1

[Rahul]

Hi @Evgeny,

I understand that you wish to set a 1 second timeout before throwing an error while using 'webwrite' for the dummy url. You are experiencing a delay of 30 seconds before the error is being thrown.

The following behaviour is observed because:

• 'http://dummy' triggers a DNS lookup, which fails slowly (up to 30 seconds), especially if the domain doesn’t exist.
• The 'Timeout' value (even if set to 1 second) is ignored during DNS resolution.

As a workaround to test the 1 second timeout, consider using a non-routable IP address. This would bypass the DNS step and trigger the TCP timeout.

Here is an exmple:

webwrite('http://10.255.255.1', 'blah', weboptions('Timeout', 1));

The following MathWorks documentations can be referred:

'webwrite': https://www.mathworks.com/help/matlab/ref/webwrite.html

'weboptions': https://www.mathworks.com/help/matlab/ref/weboptions.html

Thanks.