Quoting from TechTarget

With the emergence of virtualization as an option for application delivery to user desktops, IT shops have something new to weigh when considering the consolidation of application resources.

When most technical experts refer to application virtualization, what they are talking about is application streaming, which is a job handled by products such as SoftGrid technology from Microsoft's recent acquisition of Softricity, Altiris Inc.'s Software Virtualization Solution and Project Tarpon, currently in beta from Citrix Systems Inc.

This contrasts with server-based computing and thin client computing, which is also occasionally referred to in marketing parlance as an application virtualization technology. Here the term virtualization is used in a more comprehensive manner. The products widely used for thin client computing come from Citrix, based in Fort Lauderdale, Fla., and Microsoft.

Application streaming

The big difference between application streaming and server-based computing is that in the former, the application executes on the desktop, running as if it were on the client. In the latter, applications are physically installed and are executing on back-end servers.

"[In application streaming], instead of being installed, however, [the application is] being downloaded on demand," said Brian Madden, a Washington, D.C.-based analyst. "If you have an application like Office, it will copy your application down even as you are using the application."

The term virtualization comes into the picture when, in order for the technology to work, there must be a client agent running on the workstation. This client agent provides a virtual sandbox in which the application can run.

There is also the streaming component itself -- a packaged application that resides on the server and is streamed to the workstation. The technology is helpful for administrators who are managing remote desktops using tools such as System Management Server and who now don't need to necessarily care what is running on those workstations.

And because the applications run locally, desktop virtualization products can work when the client devices are not connected to the network. With applications running locally, it also means that thousands of users can receive streamed applications without requiring big servers.

Because application streaming technology is so new, there is still a lot about it that is unknown, such as its ability to scale, said Mark Margevicius, a research director and vice president at Gartner Inc. in Stamford, Conn.

"There's not a lot of traction yet in the marketplace and not a lot of third-party tools to manage the environment," Margevicius said. "There's a lot of work that needs to be done."

Server-based computing

Microsoft's Terminal Services and Citrix Presentation Server (which is derived from Terminal Services technology) are another way to deliver applications without installing software on an end point.

Thin client computing has some key advantages. First, in the case of the Citrix software, applications can be accessed from any platform. Streaming technology from Softricity and Altiris are for Windows-only clients, whereas Presentation Server connects any application to any device.

Also, there is no major bandwidth requirement. "I can walk up to any kiosk and within 15 seconds use an application from behind my corporate firewall," Madden said.

The downside is that it requires a network connection and a substantial back-end architecture to support the applications. If there are thousands of end users to support, an IT shop needs to buy a lot of hardware.

Read the rest of the article, here.