For the most part, the user experience in a XenApp infrastructure is much the same as any terminal services environment. Depending on how the solution is deployed, users may not even realize that they're using a thin client. However, there are plentiful options to deploy XenApp applications to fat or thin clients, and even to devices like the iPhone. There are many ways to get from here to there, from the Web interface, to the Citrix Receiver client, to thin clients that boot straight to a desktop session. When run on Windows Server 2008, users can even be presented with a Microsoft Vista theme rather than the standard Windows Server 2008 desktop. For normal usage, the user will experience a quick and responsive desktop or application -- naturally dependent on low-latency connections and sufficient server horsepower -- but responsiveness will suffer somewhat for other uses, such as video playback.
Management this and that
As far as overall infrastructure management goes, XenApp 5 is quite capable. The Access Management Console is well laid out, providing a hierarchical view of all XenApp components, applications, and services, as well as simple drill-downs to view relevant performance and status data. There are a few puzzling points here and there -- such as the apparently undocumented inability for the Access Management Console running on a XenApp farm server to communicate with the Web server. The Access Management Console must be run from another system, such as an admin's workstation. That discovery was made after more than a little fiddling and frustration in the lab.
Otherwise, managing a XenApp infrastructure is a hobo stew of Citrix and Windows tools, requiring proper understanding and operation of Windows roles and features, Windows Active Directory and Group Policy Objects, all the way through profile management. Some of this will be intrinsic in any Windows shop, but be prepared to delve deeper into some aspects of Active Directory than ever before.
XenApp 5 FR2 also introduces power and capacity management, a framework for making the most out of a XenApp farm. Based on admin settings, this does a better job of load balancing, using session thresholds on running servers to gauge when it might be time to power on additional, dormant XenApp servers. This is accomplished with basic Wake-on-LAN signaling, but can help curb power and cooling costs, as only a certain subset of XenApp farm servers must be powered on at any time.
Implementing installation
Make no mistake: Implementing Citrix application virtualization is not a week-long project, but the culmination of many months of planning and testing. After all, application virtualization represents a wholesale change in the way an organization serves its users. There is no plug-and-play wizard to put all the pieces in the right place, no simple method to develop and deploy the tens or even hundreds of tweaks required to roll out a successful deployment.
This isn't a knock on XenApp -- it's also true for VDI and Terminal Services builds -- but it's a reality you can't ignore. Installing XenApp on the farm servers and configuring applications and desktops isn't the beginning of the journey, it's near the end.
Well before the production servers fire up for the first time, every application within an organization should be tested and verified to function normally within a XenApp session. The major apps like Microsoft Office are generally not an issue, but more esoteric apps, especially those from small ISVs, can be either so poorly coded or otherwise so constrained that they fail to function within a normal terminal services environment. Of course, XenApp has a few tricks up its sleeve to assist with those problem spots, like application streaming and now VM-hosted applications.