By Stephen J. Bigelow, Senior Technology Writer
This article is part of the Virtualization Explained series. For more information, check out our related articles on and storage virtualization.
Each PC requires an operating system and applications that need to be licensed, installed, patched and eventually upgraded. But as the number of PCs and applications expand across the business, desktop management becomes more problematic. This has led to the emergence of application virtualization solutions -- serving or streaming applications to client systems across the network without having to actually install or maintain the applications themselves.
Like other forms of virtualization, the goal of application virtualization is to decouple the applications from the hardware running them. "Instead of running a mail front-end application on a PC, we can pull that application back into the data center, run it on a specialized server, and serve that application up to remote devices," said Scott Gorcester, president of Moose Logic, a solution provider headquartered in Bothell, Wash. He also noted the relevance of application streaming technologies such as Microsoft Application Virtualization (App-V, formerly known as SoftGrid) along with ThinApp (formerly Thinstall) from VMware. "We would package up applications and essentially stream them bit by bit to end user devices on demand."
Application virtualization solutions promise much greater manageability in the customer's computing environment. Instead of installing, patching and updating countless individual PCs, a solution provider only has to maintain the virtual application in the customer's data center along with the service software (e.g., App-V or ThinApp) serving the application. Virtualized applications can be executed on any suitable PC platform once the user logs in. A user can run business applications from their home PC or any other geographically remote system without having to physically install an application in multiple locations. Administrators can restrict user authorization to run only certain programs, further enhancing network management and security.
What are the issues or limitations with application virtualization?
While application virtualization solutions can bring a new level of flexibility to a customer's business, it's important to note that the technology is still relatively new and requires some refinement. Every computer receiving virtualized applications must be connected to a LAN (and a WAN when located remotely), so network connectivity is an immediate concern.
"For example, if you're a laptop user and you're remote, streaming apps don't stream very well if you're not connected," said Keith Norbie, director of storage and virtualization at Nexus Information Systems in Plymouth, Minn., noting a lack of "offline mode" for virtual applications. Performance is also a potential issue. While a virtualized application should stream to any user's PC, the PC itself still needs to meet minimum system requirements to execute that program properly.
Application licensing is another challenge to deal with. Software is licensed per copy, per user, per processor or even per processor core, but the software industry has not yet established any recognized standards for virtual application licensing. Norbie suggests that virtual applications may evolve into a pay-per-use scheme like a utility. Solution providers must figure licensing expenses into other project costs.
Virtual applications are deployed (or "pushed") to desktops across the network from a central server, so it's important for virtualized desktop environments to use applications that are designed and optimized specifically for deployment across networks. Not every application is suited for virtual deployment. "Applications have to be packaged for push," said Rand Morimoto, president of Convergent Computing, a solution provider located in Oakland, Calif.
There are also infrastructure considerations. Servers (virtualized or not) and other client network facilities must support the traffic produced by virtual application users. In many cases, a solution provider will need to recommend server or network upgrades prior to deploying application virtualization solutions. "The biggest issue is the planning -- knowing how to design and properly implement the technologies and choosing the technology that might fit your customer's requirements most appropriately," Gorcester said.
