By: Chris Maher
Server App-V is an application virtualization technology designed for server-based applications. It enables administrators to create an "image" of an application that can be moved or copied from server to server to quickly deploy server applications. The goal is to enhance the use of cloud computing by being able to quickly spin up new server-side resources to meet growing demand.
There are some fundamental differences between Server App-V and App-V. The biggest difference is that application files such as .exe and .dll that are included in a Server App-V package are available to all processes running on the server. Objects such as COM, DCOM, COM+, WMI Providers and NT Services are also exposed to the local system. In App-V, these files and objects are restricted to the virtual application. As such, in Server App-V you must be cognizant of potential application conflicts, but communication with the virtual application by the local system is enabled.
Server App-V provides several PowerShell cmdlets that can be leveraged to automate the process of moving or copying applications to new servers. These cmdlets enable the movement of the application and the application state. The application state includes items such as application configuration and data collected while the application is running. Basically, any sort of change to the application or its environment is considered the application state. The ability to capture the existing state and move it is one of the key features of Server App-V as it enables the application to function and look exactly the same when moved to another server.
So, what types of applications are good candidates for Server App-V? Applications that leverage IIS are one category. This includes applications that install web sites or virtual directories, but not applications that make changes to IIS at the server level, as this would impact all applications on the server. Applications that use Windows Services can also be virtualized with Server App-V. Again, be careful to ensure that these applications won't conflict with other applications with the same services. Applications that use WMI are also good candidates.
In summary, Server App-V is a great mechanism for enhancing cloud computing. Using the PowerShell cmdlets, server-side applications can be moved and/or copied from one server to another seamlessly, without losing the current application state. This enables environments to be more flexible in terms of scaling to meet demand. It also allows for tasks such as routine maintenance to occur without any significant downtime.