Seamless Applications
Citrix introduced the concept of seamless applications over a decade ago.  Microsoft included seamless applications (called RemoteApp) in the first release of Windows Server 2008 Terminal Services.  Both Citrix’s seamless applications and Microsoft’s RemoteApp seamless applications look and feel the same to the end user for most applications. 
Note: Citrix does introduce some High Definition Extensions (HDX) for a better user experience in some use cases such as video and flash performance, but I am trying to stick with CPA related comparisons.

Application Publishing
Application publishing refers to granting users access to applications.  Citrix has always had a mechanism to specify which users get which application as well as which server can run the application.  Windows Server 2008 R1 has no such mechanism.  In Windows Server 2008 R1, once you published an application, the application was available to everyone.  Also, it was assumed the application was available on every server – which means you, the administrator, had to ensure every server had every application installed.

RDS does have some application publishing improvements, but these improvements are more like filters.  Every application is still available to every user, but you can use these filters to filter out what the end user sees.  This is not a security mechanism as users still have access to the hidden applications.
See http://blogs.msdn.com/rds/archive/2009/06/12/introducing-remoteapp-user-assignment.aspx for more information.

Multiple Monitors
Multiple monitors are commonplace in the CPA industry today.  Citrix has supported multiple monitors for some time.  Windows Server 2008 R1 “supports” multiple monitors in that applications will show up on multiple monitors, but all monitors were seen as one big monitor.  This means when you maximize an application, the application will fill up all available monitors.  There are some restrictions on monitor placement and size as well.  Windows Server 2008 R2 RDS supports true multiple monitors (up to 16 monitors).  There are no monitor placement or resolution restrictions in RDS.

Gotcha: Multiple monitor support requires the Remote Desktop Client (RDC) 7.0.  To date, only Windows Server 2008 R2 and Windows 7 support RDC 7.0.  This means no Windows XP or Vista support.  I have seen a hack to get RDC 7.0 working on Vista, but this isn’t supported by Microsoft.
See http://blogs.msdn.com/rds/archive/2009/07/01/using-multiple-monitors-in-remote-desktop-session.aspx for more information.

Web Access/Security
RDS does include a nice web portal (called TS Web Access) and SSL encryption (called TS Gateway).  These features are comparable to Citrix Web Interface and Secure Gateway.  Citrix does offer more advanced features like Smart Access and SSL VPN though.

Printing
Both Windows Server 2008 and Citrix support universal printing based on XML Paper Specification (XPS).

Scanners
Citrix has built in TWAIN support for scanning.  Unfortunately, RDS does not have this capability.  There are 3rd party solutions for this though.
Interesting fact: TWAIN stands for Technology Without An Interesting Name

Management/Infrastructure
There are a lot of infrastructure components and management tools to RDS.  To set up and maintain the even the most basic environments takes quite a bit of planning and infrastructure.  Microsoft claims RDS is aimed at low complexity environments.  But, RDS is actually pretty complex to set up and maintain.  Citrix still reigns supreme on management and Enterprise features.
See http://www.citrix.com/%2Fsite%2Fresources%2Fdynamic%2Fsalesdocs%2FCitrix-XenApp5-Terminal-Services-2003-2008-Feature-Analysis.pdf for a feature comparison matrix.

Hurdles
If you decide to give pure Windows Server 2008 Remote Desktop Services a shot in your environment, there are a few hurdles you need to know about:

• Windows 2008 R2 is 64 bit only – that means:
  • Possible hardware upgrades or purchases
  • All applications will need to run in a 64 bit environment
• A lot of features require Windows 7.
• Possible hardware purchases to meet infrastructure needs.

Conclusion
A lot of the base Citrix XenApp functionality is built in to Windows Server 2008 R2 RDS.  Microsoft is focusing on the “low complexity” environments while Citrix is focused more on the Enterprise and VDI environments.  I think any environment can benefit from the Citrix feature set, but it is up to each organization to cost justify the expenditure.  So, can you get away with just RDS?  That is a question you will have to answer for yourself.

What is Cloud Computing?

The term “Cloud Computing” comes from the symbol usually used to depict the Internet on network diagrams. That term would lead one to believe that some portion of their computing environment “lives” on the Internet (and that assumption would be true).  This type of computing environment is quite a departure from most computing environments today where all computing resources are owned and/or operated within an organization’s LAN/WAN infrastructure.

So, Cloud Computing is some type of service.  Cloud Computing can be a service for a single piece of software (like Google Docs), a single component for software (like Microsoft SQL Data Services), Virtual Servers (like Amazon EC2), etc.  The main advantage to Cloud Computing is the service provider takes care of all the capital expenditure (CapEx) and a percentage of the operational expenditure (OpEx) depending on the type of service.  For example, Google Docs takes care of 100% CapEx and 100% OpEx, whereas Amazon EC2 takes care of 100% CapEx but maybe 25% OpEx.

What is Virtualization?

Virtualization is another hot topic today.  A lot of people think virtualization means server virtualization, but the truth is virtualization is a very broad topic.  There are many types of virtualization including server virtualization, application virtualization, desktop virtualization, operating system virtualization, presentation virtualization, etc.  (I will cover the various types of virtualization in a future article).  But, for the purposes of this article, we will focus on server virtualization.

A virtual server is basically the same as a physical server based on outward appearances.  Virtual servers perform the same functions as physical servers.   In fact, it is nearly impossible to distinguish a physical server from a virtual server when logged on to the server console (unless you start to go look at drivers).  The key difference between physical servers and virtual servers is that virtual servers are not installed on the physical hardware (they are hardware agnostic).  Virtual servers are installed on something called a hypervisor.  This hypervisor allows you to run many virtual servers on a single piece of physical hardware (there are a lot of other benefits to server virtualization, but for the purposes of this article we will focus on hardware independence and consolidation).

So, Cloud Computing doesn’t need Virtualization then – right?

Well, technically, Cloud Computing doesn’t require virtualization.  But, in order for Cloud Computing to be a practical service offering, you need the economies of scale and automation capabilities of virtualization.  Otherwise, the cloud service provider would need to manually provision services per client with dedicated hardware.

Nicholas Carr draws a nice analogy in his book titled Does IT Matter? Up until the last decade of the nineteenth century, most manufacturers relied on water or steam power to operate their machinery.  These power systems were large, complex, and expensive.  Around the turn of the century, construction of central power stations in cities brought the operating benefits of electric power to small manufacturers.  These small manufacturers couldn’t afford to build their own infrastructure, but they could afford to purchase power in small quantities from a utility.  Eventually, all manufacturers converted to using power from utility companies.  Electric power is now a commodity instead of a competitive advantage.

Look for these topics in future articles:

• Types of Cloud Services (*aaS)
• Types of Virtualization
• Offline Computing in an Online World
• Virtualization and Service Oriented Architecture