What are WSD Print Providers in Windows?

Modern printers have network connectivity built-in, and thus, can be controller and configures to a great extent with simply a web browser. In addition to this, these printers can also support something called WSD, which is a printing interface specification especially on the Windows platform. WSD stands for Web Services on Devices.

WSD allows printers to be controller by the operating system in the manner for a SOAP based web API. For instance, many HP printers support this interface, and if you have one at home or at the office, you will likely see a node in your Device Manager titled "WSD Print Provider".

Now without going into details, WSD-enabled printers usually listen to SOAP client class in their configured IP address, and TCP ports 3910 and 3911. For instance, if you take a look at the properties of your device (through Device Manager), you can see details like this:

Device instance path:
SWD\DAFWSDPROVIDER\URN:UUID:434E4638-4742-5136-3353-3863BB029BCB/
HTTP://WWW.HP.COM/SCHEMAS/IMAGING/CON/WSPRINT/2007/05/HP_WSPRINT.WSDL

PnP-X service address:
http://192.168.0.233:3910/

PnP-X transport address:
http://192.168.0.233:3911/

Notice how the device instance path points to a WSDL document, and the PnP configuration contains direct HTTP links to SOAP endpoints.

For more details about the WSD interface and the associated Win32 API, check out MSDN.