Now that Citrix System Inc.'s XenApp 5.0 has been out for a few months, organizations that aren't early adopters are beginning to migrate away from Presentation Server 4.0.
XenApp 5.0 adds three features that warrant a closer look:
- Special Folder Redirection (SFR)
- Preferential load balancing (PLB)
- The new Citrix Universal XPS Printer driver
Special Folder Redirection
Having been around since Windows 95, Special Folders such as My Documents, My Computer, Desktop, etc., are very familiar to administrators. Centralizing the data in these folders is a method typically used to redirect them via group policy to a network location. This process is simple for a LAN environment, but difficult when laptops and remote users are brought into the equation.
Special Folder Redirection allows users to see the contents of special folders on their local machines via their XenApp 5 session. When SFR is enabled and a user opens the Documents folder in their session, the data they see actually resides on their local machine and not on a file server.
SFR is installed by default (Windows Server 2008/XenApp 5 only), configured via Citrix policies and requires version 11 of the XenApp Plugin (client). Before you can begin configuration, you still need to enable SFR at the Web Interface level under Manage Session preferences.
For more information on SFR, including configuration options and best practices, check out my article "XenApp 5 Feature Profile: Special Folder Redirection ."
Preferential load balancing
Preferential load balancing is an extension of the CPU Management capabilities that have been built into Presentation Server/XenApp. PLB allows administrators to assign more resources to certain users or applications based on their importance.
Administrators are able to assign an "importance level" to each user and application that, when multiplied together, result in a number called the "Resource Allotment" value. By default, all applications and sessions have an importance value of 2, resulting in a default Resource Allotment (RA) value of 4.
When connecting to a new session, users with the highest RA value will be sent to the server with the lowest aggregate RA value of all the sessions. This results in less resource contention for the more important sessions. The reverse is also true, where users with very low RA values will be sent to servers with very high aggregate values.
PLB is only available to organizations running XenApp 5 Platinum. Check out this feature profile for more information on preferential load balancing.
Citrix Universal XPS Printer driver
The last new feature deals with my least favorite part of IT -- printing. It's a necessary evil though, and if printing was not around we would have never gotten into IT in the first place.
In the past, Citrix hasn't done much to help administrators deal with the daily challenges of printing. However, with each major Universal Printer driver rollout, Citrix has improved this issue; though these improvements were typically based on existing technologies that happened to work for most, but not all, printers.
With Windows Server 2008 and Windows Vista, Microsoft has introduced a new feature called XPS, or XML Paper Specification. Citrix is now using this feature as the foundation for its Citrix Universal XPS Printer Driver (XPS UPD). XPS printing attempts to provide a platform-agnostic electronic document format similar to .pdf files. Although the Citrix XPS UPD will only work on Windows Server 2008 and Windows Vista, there are some reports that you can "make" it work with Windows Server 2003 and Windows XP by installing the .NET Framework 3.0 or 3.5.
Essentially, the XPS printing process looks like this:
A user tells the application to print, which then sends the print data to the printer object inside the user's session.
The client-side print object sends the data to the XPS printer driver on the server-side. The data is converted into an XPS file (basically an easily compressed XML file with the printing instructions).
The XPS file is sent via the printing virtual channel to the XPS Print Helper on the client side (part of the XenApp Plugin).
If the XPS Print Helper is attached to a printer already, the job prints normally. If the XPS Print Helper has not yet been attached to a physical printer, a screen appears prompting the user to select a printer before the document prints.
For more information on the Citrix Universal XPS Printer driver, including installation and configuration options, check out "XenApp 5 Feature Profile - Citrix Universal XPS Printer Driver."