Write PDF files from Web-App to USB-Stick

Question

I am concerned with the feasibility of this: On a pre-configured machine I will have a Web-Application pre-installed, next to an Apache-Suite. So client and server are the same!

In this Web-Application Users can drag and drop PDF-Files to an USB-Icon.
Then the Web-App should write the dropped PDF to an attached USB-Stick.

I have never done something like this (writing to USB), so I am fairly insecure. And I am well aware of the browser-restrictions concerning JavaScript and Filesystem-Access, but...

after researching a bit I found out, that there might be some possible and
relevant (I'm a Web-Platform-Guy) solutions to this:

• Make a "Chrome App" with USB-Permission (does this really work?)
• Use PHP to find the USB and then write to it (how would that work under Windows?)
• Use some Flash as middle man (not preferred)

Now I'd like to know:

1. Has anyone some good experience with before mentioned possibilities?
2. Has anybody ever done something similar? Did it work? Which path did you choose?
3. How would I know which drive the USB is mounted, and how would I get sure?
4. What other possible solutions to this problem are there?

Answer 1

You have a website ('client-side' user interface) and a back-end server ('server-side') running on the same machine. This gives you 2 options:

1. Client-side: Download a file through the browser via HTTP GET and let the user choose where they save it.
2. Server-side: Build your USB interactions into the back-end (Node.js) code, as @mcgraphix suggests.

Interacting with the USB on the server-side provides the most flexibility. Furthermore, there are a number of libraries that you can leverage. Head to npmjs.org and consider, among others, the following Node.js server-side packages:

• usb-detection
• usb

With the server-side approach, initiate a Webservice request when the user completes the drag & drop action on the client, and implement the USB interaction within the server (Express.js or similar) method which services the request.

Answer 2

If the letter of the stick is known then writing a file from PHP will be simple

file_put_contents( 'E:\\folder\\file.pdf', $data );

Update

You can read a list of drives into a dropdown and allow a user to select a default drive to write to

https://stackoverflow.com/a/8210132/696535