Citrix has launched the latest version of its application delivery software, now known as XenApp, following the company's acquisition of XenSource last year.

XenApp 5, replaces Presentation Server 4.5, and Citrix claims that by combining the tool with its other Xen products, users would have "an end-to-end virtualisation solution that spans servers, applications and desktops."

Citrix said XenApp 5 features load times as much as nine times faster than the previous version, more closely approximating the experience of using a natively installed desktop application. Because applications are hosted remotely and streamed out to users, they don't have to deal with the typical hassles such as upgrading to new versions or restarting when there's a problem, said Bill Hartwick, senior director of product marketing for Citrix's application virtualisation group.

"When it's streamed down to me I don't have to worry about installing it or anything. I always have the latest, greatest version of it," he said. "Not only does it start up quickly, but should anything go wrong with the application, I can just re-stream it."

XenApp places applications on centralised servers, allowing users to connect to them from remote devices. To the user, it appears as if the application had been installed on the desktop. Essentially, the presentation layer or user interface is virtualised, says Barb Goldworm, founder and chief analyst for FOCUS Consulting. "Rather than run it on your own desktop, you're running it on a server, virtualizing the presentation layer and distributing it over the network," she said.

Citrix has gone further than any other vendor in terms of virtualising both desktops and applications, Goldworm said.

Server virtualisation giant VMware got into the application virtualisation market this year by purchasing Thinstall, which has been renamed ThinApp. Microsoft offers an application virtualisation product called App-V

Citrix's XenApp 5 has new load balancing functions letting IT administrators ensure that key users and applications receive the best performance available, Hartwick said. The new version uses the HTTP and HTTPS protocols for the first time, features a redesigned interface and integrates XenApp with Citrix's Branch Repeater software, accelerating delivery of applications to branch offices.