Communicate with the local machine from a web page

Question

We have a web application. There are physical devices that we need to be able to communicate with, and we have access to all of our clients computers to install whatever software we need. Now, for the question: Is there a way to make this browser-agnostic? As in, not requiring ActiveX controls?

One of my ideas was to install a custom made webserver on each client and then have javascript on our webpage that communicates with that webserver. This could be done by the same way that http://earlz.biz.tm javascript can access subdomains assigned to 127.0.0.1 such as http://loopback.earlz.biz.tm The problem with this of course is that the client's custom made webserver would be forced to run on port 80(which will have conflicts at least sometimes), or we would have to use a nonstandard port for our web application, which is quite undesirable.

Does anyone else have ideas on how to do this?

Just to clarify. Our clients will be using regular PCs with Windows. We need to communicate with physical devices through these PCs. One such thing is a signature pad. So we want for people to be able to sign the signature pad and it show up in the web page.

Answer 1

I don't think browser-based is the solution for this. There are too many security issues. You're better off writing a desktop application that incorporates some web functionality.

Answer 2

I think web servers and possibly comet is the way to go.

Web servers can run on any port you like, as long as there aren't any firewalls blocking the ports, or they are configured to allow http traffic to pass through on different ports. Although theres nothing wrong with just using port 80 either.

On the mini web server you will then need to interact with the device. You mention you are a .net shop, so you will probably have to install linux and apache + mono on these devices - not sure if this is feasible.

Sounds like a great project.

Answer 3

I would try to look at Java Applets...

http://java.sun.com/developer/onlineTraining/Programming/JDCBook/signed.html

"JDK 1.1 signed applets can access local system resources if the local system is properly set up to allow it. See the JDK 1.1 Signed Applet Example page for details."