Is Unidesk an App-V Competitor for Application Packaging?

Posted by Thomas Willingham on Sep 26, 2016

Unidesk has been considered an App-V alternative in VDI environments since we first came to market. Now, with our new award-winning support for Citrix XenApp, where App-V is often used to virtualize apps on published desktop and application servers, we’re getting asked more frequently if Unidesk is an App-V competitor. The answer is "it depends."

  • App-V in your environment. If you have successfully deployed App-V to isolate conflicting apps, and you need a simpler, more cost-effective way to manage the rest of your apps, accelerate app delivery, and prepare for the cloud, use Unidesk and App-V together.

  • App-V not in your environment. If you haven't successfully deployed App-V, and you need a way to separate apps from the OS so they can be packaged once and delivered many times without re-installation, while also reducing image management, Unidesk may be all you need.

To borrow from Tom Cruise's response to Jack Nicholson in "A Few Good Men," I’ll use the rest of this blog to try to make it "crystal" clear what problems each solves, why the underlying architectures are so different, and how App-V and Unidesk compare to each other.

Fundamental question: Interoperability or Not?

Application interoperability has been a founding principle since the beginning of Windows. Microsoft designed the operating system to give processes and applications the ability to share objects, data and resources. Technologies and frameworks such as; DDE, COM, OLE, and .NET were refined over the years to increase inter-process communication and application interoperability. All of this work was done to create an efficient desktop environment for the user, empowering them with workspaces in which they can seamlessly use data and resources across different applications.

Application virtualization solutions, with App-V being the first, are designed to purposely ignore this foundation of interoperability in an effort to resolve software conflict issues. Application layering solutions, with Unidesk being the first, are designed to adhere to the principle of interoperability in an effort to streamline application packaging and lifecycle management. This fundamental difference sets the stage for the remaining App-V vs. Unidesk comparisons.

Application Virtualization with App-V

Application virtualization is a method of encapsulating an application from the underlying operating system on which it is run. The application is isolated from Windows and all other applications in the desktop environment. The isolated application executes in its own dedicated run time environment. All resource requests to the operating system are redirected to a virtualized location such as a single file. Since the application is now interfacing with a single file, instead of the many files spread throughout the operating system, it becomes easy to migrate the application to a different computer or operating system.


By purposely avoiding all of the inter-process communication and application interoperability work that has been designed in to Windows, App-V offers powerful benefits, but also has known limitations:


  • Once an application is packaged, repetitive software installations can be eliminated. The same package can be delivered to 1, 100 or 10,000 machines without failures.
  • Conflicts with other applications and the Windows OS can be avoided, enabling multiple versions of the same app to run on the same machine.
  • Applications that were not designed to be run by multiple users at the same time can now work in a multi-user session virtualization environment (i.e. XenApp or RDSH).
  • The same app packages can be delivered to both virtual and physical desktop environments.


  • Not all applications can be virtualized. Some apps are not compatible with the process isolation method. Applications that need access to OS-level drivers cannot be successfully packaged. The "last 30%" of apps must be delivered in other ways. Typically, this means baking them into the gold image, which results in gold image sprawl and increased Windows patching costs.
  • The packaging process is time-consuming and requires advanced IT expertise. Machine staging, app sequencing, pre-scans, post-scans, scripting workarounds, and Windows registry tweaks can take several hours for even basic apps. Complex apps can take a week or more to package, driving up operational costs. Troubleshooting packages can be complex and time consuming.
  • Interoperability is problematic. Apps that require interoperability need to be sequenced in the same package, creating large packages. Or, holes need to be poked in the packages to enable applications in separate packages to interoperate, adding more packaging time and further increasing the levels of IT expertise and line of business knowledge that are required.
  • Some independent software vendors won’t support applications that have been virtualized using application virtualization because the files and registry keys aren't in the "usual" places.
  • Apps virtualized using process isolation technologies cannot be easily migrated to the cloud.

Despite these limitations, which stem from the fact that application virtualization was designed to solve the occasional app conflict problem and not be a solution for mass software distribution, the technology is often sold as the answer to all application management challenges in VDI and session-based computing environments.

History now shows this has not served customers well. Senior IT admins with lots of packaging expertise still need 3-15 hours to virtualize a single app. Isolation creates all kinds of interoperability issues. And many apps cannot be virtualized, leaving the last 30% of applications still in gold images.

Application Layering with Unidesk

Unidesk pioneered application layering as the way to simplify application packaging and lifecycle management for all apps. Unidesk separates applications from the OS and underlying infrastructure as independent virtual disks, or "layers." Layered apps can be assigned in any order or combination, just like virtualized apps. The big difference is that the layers are merged into a unified registry and file system so that they all appear locally installed, not isolated. As a result, Unidesk adheres to the Windows design principles of inter-process communication and app interoperability.


Another difference is that Unidesk layering starts much earlier than application virtualization. Whereas App-V runs post-boot like other guest processes, Unidesk runs before Windows boot, enabling early-start apps and even Windows itself to be packaged as their own separate layers.

The last major difference is how apps can be delivered. Unidesk enables OS and app layers to be merged together before a machine boots and delivered as part of a Layered Image, solving the image management challenge in addition to the app delivery challenge. Apps can also be delivered just-in-time based on user and group credentials by mounting the appropriate virtual disks at login.


  • Full application compatibility. System services, boot-time drivers, and custom-built apps can all be layered, with none of the limitations of traditional application virtualization solutions.
  • Simplicity and speed. Creating application layers and Layered Images is a simple, straightforward process. Tier 1 or help desk administrators simply install apps as they would normally on a physical PC, without the need for advanced packaging expertise.
  • Application interoperability. There is full cross-communication between apps in different layers, as well as between apps and the OS layer. Applications show up as expected in Add/Remove Programs and the Windows registry.
  • Seamless integration. Layered Images (selected OS and app layers that are merged together into a single VHD before machine-boot) can be delivered through existing provisioning solutions such as Citrix PVS and MCS or VMWare Horizon View Composer and Instant Clones. Just configure the connectors and you’re ready to create and deliver images to your environment.
  • Platform mobility. The same application layers can be delivered across hypervisors, end user computing platforms, and clouds without re-packaging for maximum workload flexibility and business agility.


  • No application isolation. Applications are fully integrated, just as if they were installed locally. However, Unidesk is compatible with App-V (and other app virtualization tools) for applications that require isolation.
  • No physical PC support (yet). Physical PC support is coming, but today Unidesk supports only virtual and cloud environments.

Comparing App-V and Unidesk

Application virtualization with App-V and application layering with Unidesk are two ways to manage applications. Each has its own technical merits, as well as operational and capital cost ramifications.

Application Virtualization
Application Layering
App Compatibility
App Interoperability
Hypervisor Portability
Conflict Avoidance
App Isolation
Minimal IT Staffing
Minimal IT Skill
Tier 1 Staff
Install-free Reliability & Resource Efficiency
Image Reduction
One Gold OS & Apps
Deployment Speed
New Apps & Updates
Departmental & One-Off Apps
Storage Efficiency
License Optimization
Easy Rollback of Updates & Patches
Integration with Existing Provisioning
Tools for Image Delivery
Extend XenApp
Minimize Need for VDI
Cloud Support

As this table shows, Unidesk application layering offers many advantages for organizations that have diverse application requirements and multiple use cases:

  • Lowest operational cost by reducing packaging times up to 80%, by enabling helpdesk and Tier 1 IT staff to take on application lifecycle management, and by eliminating image management.
  • Fastest delivery of apps to digital workspaces.
  • Greatest increase in user productivity by permitting app interoperability and enabling instant rollback of problematic updates.
  • Most flexibility and agility, with app layers that can be moved between hypervisors, end user computing platforms, and the cloud.

This is why Gartner rated application layering to be the best way to deliver applications in VDI environments and why Unidesk is winning awards for its latest release:

Now that you better understand the differences between App-V and Unidesk, try Unidesk in your own environment to experience the differences for yourself.

Thinking of using App-V and Unidesk together? Read about the benefits of a joint App-V and Unidesk solution for robust application management. 

What is your experience with application virtualization compared to application layering? Write a comment to let us know!

Topics: Application Virtualization, Layering, App-V

Posted by Thomas Willingham on Sep 26, 2016

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