App-V vs. Terminal Services – Which one, when?

Both App-V and Terminal Services/Remote Desktop Services can reduce the amount of time an IT Professional spends installing, managing and troubleshooting applications on desktops. Both technologies allow you to install, upgrade and manage an application in one place (on a server) and allow multiple users access to those applications. And then the similarities start to end.

Terminal Services/RDS is based on session hosting. The users must establish a session with the host server to access the application. Depending on what version of Windows Server you are using, the applications can appear on the desktop seamlessly using either RemoteApp or other 3rd party technologies. While this is great for workers who are located locally in the office or are regularly connected via the Internet from another location, the applications are not accessible when the client machine is working offline.

App-V streams the packaged applications to the client machine, which are then cached locally for use while working on or offline. The applications can be managed and updated on the server side and the client machines receive updates when they reconnect. This allows for better control of the overall software lifecycle and ensures that every client is running the approved version of any given application.

When it comes to support for legacy applications, especially those that will not run on Windows 7, App-V isn’t necessarily going to be the solution. Any application streamed from App-V must be sequenced and packaged for the destination operating system, though I've heard of some success with XP-sequenced apps working on Windows 7, so your mileage may vary. App-V requires the applications to interact with the client operating system in order to take advantage the local system resources. This is also important for applications that must interact with each other and with the local drivers on the machine, to deliver an experience similar to having the application installed in the traditional fashion.

If you have an application that won’t run on Windows 7, you’ll have to turn to a solution other than App-V. If you already have a legacy Server 2003 Terminal Services infrastructure in place that can deliver the application, it might be easier and more cost effective to look at using that instead of deploying MED-V. (See my post on TS vs. MED-V in April.)

Legacy applications aside, what if all your applications are Windows 7 ready? Can RDS make more sense than App-V?

First, you have to consider your users. Do the work online or offline? Do you have the RDS infrastructure to support having EVERYONE access applications during the work day? Having everyone access hosted applications is resource intensive on the server. If you currently have an implementation that used for only a few remote workers or for little used applications you’ll have to look closely at how much those servers will be able to support. App-V might be a better fit if you want to take advantage the resources on the local machines instead.

You can also combine App-V with Remote Desktop Services to make better use of server farm resources. Ultimately, there are a lot of different ways to deliver software to your end users and it doesn’t have to involving managing applications on each desktop.