Used to be, when you thought of thin client computing, you had only two choices: Microsoft Terminal Services and Citrix MetaFrame. Microsoft Terminal Services sufficed for smaller installations, while Citrix MetaFrame was the pick for big jobs, offering many enterprise-level features, including the ICA protocol, which is still a far better transport than RDP.

But that was then, this is now. Microsoft has bolstered its terminal services capabilities somewhat, and the thin client desktop market has new competition from VDI (Virtual Desktop Infrastructure) technology and the many vendors who provide it. But while there may be more options, Citrix still has the best application virtualisation solution.

While it may seem that Citrix changes the name of its flagship product every other Tuesday, Citrix XenApp 5 has very much in common with the halcyon days of MetaFrame. The management tools are slicker, and the options and features more plentiful, but it's all built around the same basic core that brought Citrix to the top of the market. MetaFrame was and XenApp is the most solid, stable, and malleable way to serve desktops and applications to users without the need for a fat PC at every desk.

New tricks

The best becomes even better on September 29, when Citrix makes the XenApp 5 Feature Pack 2 available for download. This latest revision offers significant new enhancements to the user experience, like Flash offloading and dynamic USB storage support, as well as nice additions for administrators. These include new load testing and server provisioning services, as well as the big one: VM-hosted applications.

Flash offloading is essentially a way to push a Flash object directly to the user terminal, rather than using server-side resources to process and display the object. Offloading to the client can significantly enhance the playback of Flash videos -- but only for client devices that have a local copy of Flash equal to or higher than the version installed on the server. This may not be possible for some thin clients.

Dynamic USB storage support simply means that the process of plugging a USB flash drive into a client and having that volume appear in the session is streamlined.

The load testing and provisioning services provide a better method to properly size, test, and deploy a XenApp farm, including the ability to automatically provision new XenApp servers as load requires. This is a basic image and PXE-based deployment tool, not unlike Altiris, that can provision both XenApp servers and VMs. Note that the full capabilities of the provisioning tools are available at only the Platinum level.

Virtualisation, three ways

The bigger deal is VM-hosted applications. Previous to this feature, XenApp provided two ways to deliver an application to a client: through simple server-hosted applications and desktops and through application streaming. Server-hosted applications use the classic Citrix display-only delivery method, whereas application streaming is a way to use the client's processing power to run the application as if it were installed natively on the client, without the need to actually install the app.