webinos logo Discovery Plugin

This is an early demo of enabling web page scripts to discover devices and services on local networks, Bluetooth and USB. For local networks, three different discovery protocols are supported: multicast DNS, SSDP and SLP. The demo uses a NPAPI plugin that exposes the following asynchronous methods:


These return immediately after spawning threads that call back to the following methods respectively on the object passed to the scan methods:

   mdns(name, type, interface, address, port)
   ssdp(address, port, description)
   bluetooth(address, name, devclass)
   usb(address, devclass, description)

The various discovery protocols can be invoked concurrently. The demo maps the Bluetooth device class fields to human friendly names using javascript. The usb scan does this internally based upon the vendor and product identifiers using a copy of the list maintained by Stephen Gowdy (see usb.ids).

Future work will add a second argument to the scan methods for searching for specific classes of device/service. Each discovery mechanism has its own vocabulary, and an overarching taxonomy would help web page developers by shielding them from unnecessary details by enabling a higher level discovery interface.

The discovery mechanisms vary in their responsiveness. USB is very fast. Multicast DNS is also fast as it makes use of a local mDNS agent (the Avahi daemon). The SSDP code sends a search probe and listens for unicast responses and background multicast notifications. Improvements in responsiveness are anticipated as we learn more about the internals of each library.

Devices willingly participate in the discovery process, and in most cases it is possible to disable discovery. As an example a printer may offer a web page that allows users to enable or disable discovery for various protocols.

Having discovered a given device/service, you may need a specific driver to access it. We are working on a generic mechanism to identify, download and install drivers from trusted sources. This will be subject to user approval as will a request by a web application to make use of a given device/service.

The demo is currently limited to Linux and relies on the following libraries:

The Makefile copies the plugin to ~/.mozilla/plugins/ for use with Firefox. To load the plugin in chrome, start the browser and use the following menu:

 Tools | Extensions | Load unpacked extensions |
    Select directory .mozilla/plugins/

To run the demo load test.html.

This work has been funded by the European Commission as part of the FP7 project "webinos" which seeks to provide a secure web platform for applications running on mobile, desktop, home entertainment systems, e.g. TV, and infotainment/head units in cars. For more details, see http://webinos.org/.

The demo is available as open source under the Apache2 license and was created by Dave Raggett (W3C) and Ziran Sun (Samsung).

In case you are wondering how this relates to Web Introducers, the above work is about discovering local devices and services. What devices do you have at home? What devices are there when you visit a friend's house? Devices can be switched on or off, and many are portable, so the availability of devices is time dependent. By contrast, Web Introducer is essentially a brokering mechanism for web page scripts to locate cloud based services and as such the two are complementary.

Consumer electronics embed low level discovery protocols, and as a result, support for these protocols is very widely deployed. The aim is to expose these protocols in an easy to use way for web page scripts, so that web developers can create applications that span devices.

If you have any questions please contact:

Dave Raggett at <dsr@w3.org>

Here is a transcript from test run

The following services were found with multicast DNS:

 Web Site: Samsung CLP-310 Series, wlan0:
 Internet Printer: Samsung CLP-310 Series, wlan0:
 Workstation: ivy, wlan0:
 Workstation: ivy, wlan0: fe80::221:6aff:fe2f:97d4:9

The following services were found with SSDP (UPnP):

 InternetGatewayDevice: Belkin N Wireless ADSL Modem Router,
 Printer: Samsung CLP-310 Series (,

The following services were found with SLP:


The following services were found with Bluetooth:

 SGH-D900, 00:1A:8A:C3:1F:B9 capture, object transfer, phone, cellular

The following services were found with USB:

 0c45:63f8 239 Sonix Integrated Webcam
 413c:8157 0 Integrated Keyboard
 413c:8158 0 Integrated Touchpad / Trackstick
 413c:8156 224 Wireless 370 Bluetooth Mini-card
 0a5c:4500 9 BCM2046B1 USB 2.0 Hub (part of BCM2046 Bluetooth)
 0a5c:5800 0 BCM5880 Secure Applications Processor
 1267:0201 0 A4Tech SWOP-3 Mouse