VMware acquired application virtualisation vendor ThinApp in January and ThinApp 4.0, launched in June, is the first fruit of that takeover.

Securing Windows applications for mobile professionals, as well as allowing network access by onsite contractors, partners and just ordinary guests, is an age-old problem that application virtualisation using ThinApp neatly solves.

Application virtualisation decouples the application from the operating system (OS), unlike hardware virtualisation which merely decouples the OS from the hardware. This means that applications can run on exotic hardware providing the OS has the requisite drivers.

The upshot is that, in theory, IT managers can rollout conflict-free applications packaged into what VMware says is a "virtual bubble" containing the application as a standalone executable or Microsoft Installer file extension.

User data is stored in an application embedded sandbox, or one which resides on a network drive, and is renewed after each application deployment.

To review ThinApp we downloaded a trial evaluation of the ThinApp Virtualisation Suite, which has the latest release copy of VMware Workstation 6.0.4 included, along with ThinApp 4.0.

VMware Workstation is included in the suite because it allows the required application to be virtualised on a clean system. The snapshot function of Workstation can keep it clean through its ability to roll back to a desired state, which would be fully patched but with no third-party applications installed.

The alternative way was to create a clean, fully patched operating system, and back up the system image using either Windows Vista's built-in tools or something like Symantec's Ghost imaging utility on Windows 2000 and XP Professional systems, to create an OS image on a separate disk partition or external hard drive.

ThinApp can then be run on a shared drive and, after the virtualised application has been created, the OS can be re-imaged back to a clean state.

New features like Application Link and Application Sync solve the problem IT managers had in building virtual applications that would automatically update when application security updates came out. Before, each security update or service pack release necessitated a rebuilding of the application.

Installing both ThinApp 4.0 and VMware Workstation was quick and easy, and we created fully patched virtual machines for Windows 2000 Professional, Windows XP Professional and Windows Vista Ultimate.

To create a packaged application deployable to a USB stick, ThinApp was first used to scan the clean operating system. We then installed Microsoft Office Word Professional 2003, and rescanned the system with ThinApp.

The second ThinApp scan captures file system and registry changes, which define an application installation. We then built the application and rolled out to both a USB stick and a network drive on a separate system.

We could install the virtualised application using the USB stick or by executing the MSI on the network drive with no problems.

After this we set up ThinApp to work with Active Directory. We installed VMware Workstation on a desktop connected to our vnunet.com domain, and we could build applications configured to be run only by certain Active Directory groups and store them on our file server.

Because ThinApp decouples the application from the OS we could run applications on Windows 2000 Professional systems and log-on to our Active Directory domain and run the same applications on Windows XP Professional or Windows Vista systems.

The ThinApp manual says that "this functionality allows most applications to instantly migrate to newer or older operating systems". IT managers will still have to check whether this is the case, though, and certify that the application runs properly on specific operating systems.

One of the new features of ThinApp 4.0 is Application Sync, which we could use to build a Microsoft Office 2003 Word application. This allowed us to pick up later Office service packs off the web without having to rebuild the entire application.

The other key new feature is Application Link, which gives IT managers the ability to build applications that have interdependencies on other applications.

Integrating ThinApp with Active Directory, and Application Link and Sync, gives IT managers better control through group policy. However, building applications using the system is not trivial, a fact emphasised by the two-day and five-day workshops VMware has set up to advise enterprises using application virtualisation.

VMware has also released the ThinApp Application Packaging Framework, a best practice guide for application conversion.