I’m getting behind on my blogging (my day job keeps getting in the way) but this post continues the series I started on Microsoft’s virtualisation technologies. So far, I’ve set the scene, looked at host/server virtualisation and desktop virtualisation and this time it’s Microsoft Application Virtualization – formerly known as SoftGrid and also known as App-V.

Microsoft provides a technical overview of App-V but the basic premise is that applications are isolated from one another whilst running on the same operating system. In fact, with App-V, the applications are not even installed but are sequenced into a virtual environment by monitoring file and registry changes made by the application and wrapping these up as a single file which is streamed to users on demand (or loaded from a local cache) to execute in its own “bubble” (technically known as a SystemGuard environment). Whilst not all applications are suitable for virtualisation (e.g. those that run at system level, or require specialist hardware such as a “dongle”) many are and one significant advantage is that the virtualised applications can also be run in a terminal services environment (without needing separate packages for desktop and server-based computing). It’s worth considering though, that virtualising an application doesn’t change the license – so, whilst it may be possible to run two versions of an application side by side, it may not be allowed under the terms of the end user license agreement (e.g. Internet Explorer).

I wrote a post about application virtualisation using Softricity SoftGrid a couple of years ago but, with App-V v4.5, Microsoft has made a number of significant changes. The main investment areas have related to allowing virtualised applications to communicate (through a new feature called dynamic suite composition), extending scalability, globalisation/localisation and security.

Of the many improvements in App-V v4.5, arguably the main feature is the new dynamic suite composition functionality. Using dynamic suite composition, the administrator can group applications so that shared components are re-used, reducing the package size and allowing plugins and middleware to be sequenced separately from the applications that will use them. This is controlled through definition of dependencies (mandatory or optional) so that two SystemGuard environments (App-V “bubbles”) can share the same virtual environment.

On the scalability front, App-V 4.5 also takes a step forward, as it provides three delivery options to strike a balance between enterprise deployment in a distributed environment and retaining the benefits of application isolation and on-demand delivery. The three delivery options are:

• Full infrastructure – with a desktop publishing service, dynamic delivery and active package upgrades but requiring the use of Active Directory and SQL Server.
• Lightweight infrastructure – still allowing dynamic delivery and active package upgrades but without the need for SQL Server, allowing application streaming capability to be added to Microsoft System Center Configuration Manager or third party enterprise software delivery frameworks.
• Standalone mode – with no server infrastructure required and MSI packages as the configuration control, then mode allows standalone execution of virtual applications and is also interoperable with Microsoft System Center Configuration Manager or third party enterprise software delivery applications but it does not allow dynamic delivery or active package upgrades.

Additional scalability enhancements include background streaming (auto-load at login or at first launch for quick launch and offline availability) and the configuration of application source roots (for a local client to determine the appropriate server to use) as well as client support for Windows Server 2008 Terminal Services (in Microsoft Application Virtualization for Terminal Services). There are also new options for resource targeting for the application, open software description (OSD) and icon files, enhanced data metering (a WMI provider to collect application usage information) and better integration with the Windows platform (Microsoft Update and volume shadow copy service support, a System Center Operations Manager (SCOM) 2007 management pack, group policy template support, a best practice analyser and improved diagnostic support. Finally on the scalability front, the sequencer has been enhanced with a streamlined process (fewer wizards and less clicks), MSI creation capability (for standalone use), improvements at the command line and differential SFT file support for updates.

App-V is not the only application virtualisation technology (notable alternatives include VMware ThinApp – formerly Thinstall and Symantec/Altiris SVS) but it is one of the best-known. It’s also an important component of the Microsoft Virtualization strategy. In the next post in this series, I’ll take a look at presentation virtualisation.

Finally, it’s worth noting that I’m not an application virtualisation expert – but Aaron Parker is – if you’re interested in this topic then it’s worth adding Aaron’s blog to your feed reader.