How to send data outside of the browser sandbox?

I'm creating a (vaadin) web application with java. I will also have the requirement to send data from within the client browser to a local application of the user.

The user clicks a specific button, and the data is pushed to a local application on his machine, eg through a socket or whatever native OS functions. I will only have to support applications on windows.

Question: how could I achieve this? Of course the browser itself is a sandbox, so I cannot just get the data out of it directly.

Is there any chance?