Before I was a VMware guy, I was actually a Citrix guy, back when the MetaFrame 1.8 server-based computing platform ran Windows NT4 Terminal Services Edition. I used to be a Citrix Certified Instructor and a Citrix Certified Enterprise Administrator, so I spent a lot of time with the company’s wares, but my last real interaction with Citrix products was with Presentation Server in 2003.
I decided to get up to speed with Citrix’s current desktop offerings and compare its latest software with what the competition has to offer. To do that, I spent three days in Dublin with Citrix’s “Support Readiness Team,” which trains people to support new products. Here is some of what I learned about
The evolution of XenApp
Though it took a while to rediscover the Citrix part of my brain, I realized much of the XenApp architecture is the same as previous editions. Services such as the Independent Management Architecture and the Local Host Cache and roles like the Data Collector remain in XenApp 6. But Citrix has also invested in its core technology in recent years and implemented incremental changes.
Though Citrix’s back-end policy database still exists, Citrix walked away from developing its own management console in 2003 and moved its core management to the Microsoft Management Console (MMC). Now, Microsoft Group Policy Objects are used to apply settings, and Citrix is tightly integrated with Microsoft Active Directory.
Citrix XenApp 6 integration with Active Directory lets admins allocate users to desktops or applications using Active Directory organizational units or user groups. Admins can also use worker groups in Active Directory to control which XenApp server will service user requests for a specific desktop or application.
Citrix appears to be moving toward a much more policy-driven approach for all its product settings, which is nice to see because the old “farm,” server and protocol settings had confusing rules regarding which settings dialog box took precedence over another.
VMware could learn from Citrix’s settings model, because there are many different settings located on different objects in vCenter. In fact, I wouldn’t be surprised if future editions of VMware vSphere use a similar policy-driven approach for assigning settings and configurations to clusters, resource pools, data stores and virtual machines, all tied to different service-level agreement requirements.
The method of deployment for XenApp and the applications it provides have also changed. During the MetaFrame/Presentation Server days, admins had to hand-build and script XenApp installations. Now, Citrix recommends streaming XenApp server into a virtual machine using Provisioning Services wherever possible. As a result, admins can spin up additional servers when necessary without violating the conditions of their license agreements. This streamlined approach spills over into how Citrix delivers virtual desktops in general.
Citrix's focus has shifted from legacy server-based computing and Terminal Services to virtual desktop technologies. But I don’t think that Citrix intends to abandon the technology that made it famous. There is still a lot of value in the Terminal Services approach, and by continuing to support it, Citrix is able to provide customers with more desktop delivery options.
Citrix has many complementary methods for delivering applications and desktops, including XenApp and XenDesktop, and they give the company an edge over competitors such as VMware, which only offers virtual desktop infrastructure (VDI). I personally think that VMware needs a XenApp-style product so it can go head-to-head with Citrix.
During my time with Citrix’s Readiness Team, I also learned about the latest version of Provisioning Server and XenDesktop, as well as how the latter compares with VMware View 4.5, which I spent a good part of the year writing about for a VMware View 4.5 guide.
In part two of this series on Citrix desktop technologies, I’ll draw out some of the parts that I really liked and explain why I don’t like how XenDesktop is different from View.
ABOUT THE AUTHOR:
Mike Laverick (VCP) is an award-winning expert and author who has been involved with the VMware community since 2003. He is a VMware forum moderator and member of the London VMware User Group Steering Committee. Laverick is the owner and author of the virtualization website and blog RTFM Education, where he publishes free guides and utilities aimed at VMware ESX/VirtualCenter users.