Bake-off: Application Virtualization

AppStream/Symantec Altiris Software Virtualization Solution Professional
Symantec's Altiris Software Virtualization Solution (SVS) Professional combines AppStream's software to add streaming capabilities to SVS. Together, the two technologies provide a powerful SaaS delivery system that offers granular control over applications. Both technologies complement each other but can also work separately. Under the hood, both technologies use the same framework so they are similar. Symantec, however, uses extra layers in its software to manage applications better.

As far as application behavior, performance, functionality and visibility from a user's point of view, there's no difference between conventionally installed applications from CDs and applications streamed by AppStream. It emphasizes what the end user is experiencing. According to AppStream, users shouldn't have to worry about opening files differently or having to slow down due to performance degradation.

Like Symantec, AppStream built a filter driver to work with Microsoft's filter driver framework. The AppStream driver intercepts calls into the operating system to interact with file system calls, just like real-time compression software does when it compresses files into drives. This is the same framework used by antivirus software vendors such as Symantec and McAfee.

By intercepting calls from applications, the AppStream filter driver monitors file blocks used during execution. As soon as an application gets to a state where it stops and waits for user inputs, the AppStream server saves that file block. Essentially, the server learns how much to deliver next time users execute the application. The server delivers the whole file chunk and starts the application.

The AppStream server delivers a 4K file block directly into memory when executing applications and subsequently saves it in the application file for future use. Therefore, every block only needs to be streamed once, and then it is cached in a system. The second time, users can start a program without streaming. Programs simply run. In fact, control is more granular. Application executions can be controlled in offline or online modes. In online mode, applications do not execute unless they are connected to a server. Streaming applications are more controlled in online mode.

Conversely, applications in offline mode do not need server-side access. When running applications in offline mode, the filter driver downloads all of the application files and allows the executable to function while disconnected from the server.

Because applications are fully controlled by the filter drivers, they can be uninstalled even if they're running in offline mode. Solution providers offering SaaS application streaming as a subscription or in a pay-per-use model can maintain full control over applications at all times.

AppStream does not limit users in what they can store on local machines. Users can also access data from any network share and port. AppStream doesn't affect Windows security directly either.

Streaming applications eliminates the need to convert existing desktop applications. For instance, Brodenbund, an AppStream customer, recently transferred some of its software into AppStream streaming server without changing any code. Brodenbund simply integrated its e-commerce site with the streaming server so it can deliver applications.

AppStream sells directly to SMB customers with small IT staff to better manage applications. The company also sells the streaming server as a SaaS delivery product to ISVs, MSPs and solution providers with expertise in distributing software. AppStream also provides a hosted solution for small companies and solution providers servicing the SMB market.

The AppStream server can even control application versions seamlessly. Different versions of the same application can be swapped automatically from the same link. The transfer is so smooth that it is completely undetected. This capability is invaluable to companies struggling to maintain a cohesive change management process.

AppStream's Application Manager shows how much of application files are delivered at any time. The manager displays by percentage how much of an application has passed to an end user. The streaming is extremely efficient at passing only what applications request.

Symantec's SVS takes AppStream up a notch by providing a zero footprint in the operating system when running applications. The SVS layers encapsulate applications in a Virtual Software Package that can be distributed through any method. With the release of SVS 2.1, however, Symantec offers the AppStream technology for its delivery mechanism.

Since Altiris' core expertise is in desktop configuration management, SVS provides a high degree of stability in its application delivery solution. SVS can also remove applications cleanly without disrupting any operating system files, including registry fields.

Citrix Presentation Server
Citrix Systems provides an end-to-end solution to application virtualization. The Citrix Presentation Server is the old boy on the block as far as providing application virtualization. For more than a decade, Presentation Server has been providing application access in presentation mode. The technology has been an extremely successful model for the company.

Now that the space is evolving and expanding to service disconnected users, Citrix added a kernel mode component to its Presentation Server. With Citrix's new Enterprise and Platinum application streaming editions, solution providers now have the ability to create virtualized applications and stream them through the Presentation Server or directly to client devices like laptops and desktops.

Vendors such as Macrovision also provide complementary products for the Citrix application virtualization solution. Macrovision's AdminStudio, for instance, can create Citrix profile packages for streaming applications through the Presentation Server.

The Citrix Profiler creates an image of everything that an MSI or executable-based installer does to a machine. The image is then stored on a file share, and the application is published. The streaming technology uses Citrix's proven application delivery system.

After users log into machines, they get icons on their desktops. By clicking on an icon, the Citrix application driver initiates a download of an application. The streaming technology only sends file chunks that are requested by the executable. Essentially, the Citrix streaming delivery mechanism works like AppStream's streaming solution.

Because of the new streaming capabilities, the Presentation Server licensing is sold with the ability to acquire additional licenses. The concurrent user license model needed improvement because of the new access capabilities.

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