Question

How should this be implemented?

1. User has a USB device (“doorbell”) attached to their machine.
2. User goes to the client’s web page and clicks a link.
3. A notification appears “Please press the doorbell.”
4. User presses doorbell, website is notified.

The “doorbell” is actually a complex device with its own SDK, and it’s sending back a big blob of data. The device manufacturer provides SDKs for both Windows and OSX. I can write native code for either platform to interact with the device at the OS level.

Plan A

1. LocalWatchdog process runs on the user’s machine.
2. Browser plugin catches the webpage event
3. Browser plugin does something (using NPAPI?) to signal LocalWatchdog
4. LocalWatchdog pops the notification & gets the doorbell-press event
5. LocalWatchdog does something to tell the plugin that the doorbell has been pressed.
6. The plugin tells the website.

Plan B

1. The website downloads a Java applet which runs locally on the user’s machine.
2. The applet pops the notification.
3. The applet does something to catch the doorbell-press event.
4. The applet tells the website the doorbell has been pressed.

Other plans welcomed, but in any case, what are the somethings?

• Any language is acceptable.
• Non-trivial installation process is acceptable.
• Must run on OSX and Windows. If I have to write it twice, I will.
• Must run with Chrome, Firefox, and IE. If I have to write it three times, I will.

Answer 1

If you have a local process, I’d say:

1. Run a local webserver that talks to the hardware and uses an appropriate cross-domain XML file.
2. Use an Ajax call to ask speak to it from the browser and ask for the button press
3. When the local webserver gets the request, hit the hardware with an appropriate message (I’m assume its some USB HID-type thing).
4. Signal the user in the browser, then open a long-polling request again to the local webserver and wait for a response.
5. If the user hits the button, return the data to the browser request.
6. Profit (we hope).