Q: What is TWAIN?

A: The TWAIN initiative was originally launched in 1992 by leading industry vendors who recognized a need for a standard software protocol and applications programming interface (API) that regulates communication between software applications and imaging devices (the source of the data). TWAIN defines that standard. The three key elements in TWAIN are the application software, the Source Manager software, and the Data Source software. The application uses the TWAIN toolkit which is shipped for free.

For more details on TWAIN protocol, see http://www.twain.org/.

TWAIN Redirection Support with XenApp

XenApp and the ICA protocol can redirect client-connected TWAIN imaging devices, notably document scanners, from the client to the server, regardless of connection type. This allows users to control client-attached imaging devices from applications that run on the server and the redirection is transparent.
 
Note: Version 9.x or later of the ICA Client for 32-bit Windows is required for this feature.
 
To capture an image, users connect to a server from a client machine that has an imaging device and the associated vendor-supplied TWAIN driver installed locally. When the TWAIN application is run from within this session, the application detects and interacts with the client-side device. The server-based application that is accessed runs as a client-based application.

Enabling TWAIN Redirection

You enable the redirection of TWAIN devices by enabling the policy rule Configure TWAIN redirection.

1. Open the properties of a policy in which you want to control TWAIN redirection.
2. Enable the rule Client Devices > Resources > Other > Configure TWAIN redirection.
3. Use the options to allow and disallow TWAIN redirection, as well as control the level of data compression.

 Consider the following after enabling TWAIN redirection:

• The image acquisition software must be installed on the XenApp Server. Examples of supported applications include Microsoft PictureIT, OmniPage, PaperPort, Photoshop, Paint Shop Pro, and IrfanView.

Note: 16-bit TWAIN drivers are not supported.

• Image acquisition software that provides the USB device drivers must be installed on the client platform.

This article contains TWAIN Redirection Support with XenApp FAQ.