title: How to check the version of our software from a browser?
body: <p>We have a legacy software package made for native Windows. I'm writing a system to automate installing updates. One of the options is for the client to visit a web page, and from that web page, check for updates to their installation. There are two ways of identifying the software version: either reading a particular EXE file and looking at its file version, or reading the registry for our software (actually the third way is reading from their SQL Server database but that's obviously out of the question). Either of these methods would work, but I have no idea how to do it from javascript in a browser.</p>
  
  <p>I'm sure there is some security, but I have seen other systems do this, so I'm sure it's possible. In general, the web page can check the client's computer for existence of certain software, and if it exists, check for the version. How can I do this from Javascript?</p>