Citrix Virtual Channel SDK for Citrix Workspace app for Linux

The Citrix Virtual Channel Software Development Kit (SDK) provides support for writing server-side applications and client-side drivers for additional virtual channels using the ICA protocol. The server-side virtual channel applications are on XenApp or XenDesktop servers. This version of the SDK provides support for writing new virtual channels for Workspace app for Linux. If you want to write virtual drivers for other client platforms, contact Citrix.

The Virtual Channel SDK provides:

  • Description of the architecture of the ICA protocol as it relates to virtual channels.
  • The Citrix Virtual Driver Application Programming Interface (VDAPI) used with the virtual channel functions in the Citrix Server API SDK (WFAPI SDK) to create new virtual channels. The virtual channel support provided by VDAPI is designed to make writing your own virtual channels easier.
  • Working source code for several virtual channel sample programs that demonstrate programming techniques.
  • The Virtual Channel SDK requires the WFAPI SDK to write the server side of the virtual channel.
  • Example pre-built server-side executables and Linux client-side x86, x64, and armhf virtual drivers to aid initial development.
  • Debug libraries which provide basic tracing functionality.


Output functions AppendVdHeader, OutBufAppened, OutBufReserve and OutBufWrite are now deprecated. All newly written virtual drivers must use the single QueueVirtualWrite function.

Finding documentation

The Citrix Virtual Channel SDK Programmers Guide is automatically installed when you install the Virtual Channel SDK (default location: docs/vcsdk.pdf). To open the guide, double-click the vcsdk.pdf file.


  • For the latest critical updates of Citrix products, see

  • For information about new features and system requirements, see the product administration guides.

Getting support

Citrix provides technical support primarily through Citrix Solutions Advisor. Contact your supplier for first-line support or use Citrix Online Technical Support to find the nearest Citrix Solutions Advisor.

Citrix offers online technical support services on the Citrix Support website. The Support page includes links to downloads, the Citrix Knowledge Center, Citrix Consulting Services, and other useful support pages.

The Citrix Community website is the home of the Citrix Developer Network and all technical resources and discussions involving the use of Citrix SDKs. You can find access to SDKs, sample code and scripts, extensions and plug-ins, and SDK documentation. Also included are the Citrix Developer Network forums, where technical discussions take place around each of the Citrix SDKs.

Citrix Virtual Channel SDK for Citrix Workspace app for Linux