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Where does application layering fit in the virtualization puzzle?

App layering is a valuable tool for IT pros looking to virtualize applications because it allows them to deliver specific apps to specific users based on a wide range of criteria.

Layers are everywhere. At a wedding, there's bound to be layer cake. Anyone who goes out in the frigid cold of winter puts on layers to stay warm. Earth itself is made up of layers. So it's only natural for layers to be a part of application virtualization.

Application layering may still be somewhat of a niche technology, but its versatility is helping it gain traction because it allows some IT administrators to pinpoint the exact users who need to work with specific apps and to deliver the apps directly to them.

As this burgeoning technology continues to grow, IT admins must understand how it works, how it compares to application virtualization and who the big players are in the market.

What is application layering?

Application layering is a method for delivering virtual apps to end users based on different criteria, such as group or location. It helps admins deliver the right apps to the right users. The apps run on a layer separate from the virtual desktop itself. Admins can make changes to the apps, update them and manage them separately from a virtual desktop's base image. As a result, admins have fewer base images to deal with, and may even be able to use a single golden image for their virtual desktops.

Apps delivered through layering interact with the operating system and any other apps as if they were installed locally. Application layering is ideal when virtual apps must communicate directly with users' devices, kernel drivers or other apps.

How does application layering work?

Each application layering tool is unique, but they all follow a basic three-layer structure. The bottom layer is the virtual desktop's primary hard disk, where the virtual desktop operating system lives. The middle layer is home to everything that puts meat on the apps' bones, including binaries, registry keys, drivers and more. The final layer hosts users' profile data and keeps it separate from the operating system.

One way to think of it is like a sandwich. The bottom layer and the user data layer are the bread, which every sandwich needs. The middle layer includes the ingredients, which change depending on the sandwich.

Each application layering tool is unique, but they all follow a basic three-layer structure.

Individual applications usually make up their own layer, which is what allows admins to deliver specific apps to specific users. As a result, IT admins may deliver more than three layers to a particular user. They deliver the bottom and middle layers, as well as the user profile layers for each application the user works with.

How does application layering differ from application virtualization?

VDI shops should not consider app layering as a replacement for more conventional app virtualization tools, such as Citrix XenApp or VMware ThinApp. Virtualization tools can deliver apps that are not compatible with the base operating system, but app layering is dependent on the OS.

Another difference is that application virtualization tools such as XenApp and ThinApp run into process isolation issues, where each application runs completely separate from the operating system and any other applications. As a result, the applications cannot communicate with each other as well.

What are the top app layering tools on the market?

There are three major products in the application layering game: VMware App Volumes, Liquidware Labs FlexApp and an offering from Citrix. Citrix is replacing its AppDisk product with technology from Unidesk, which it acquired early this year. 

Next Steps

Application layering pop quiz

A closer look at FlexApp

Guide to virtual app delivery tools

Dig Deeper on Application virtualization and streaming

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What is the best use case for application layering?
"What is the best use case for application layering? - Eddie Lockhart

Good story. To start the discussion on your question....What we've seen with real world is adoption of Application Layering in at least four key use cases...

1) Minimize Base Image Management. Managing applications the old way is messy. Snapping them in at logon with Application Layering keeps Base image management streamlined. This is of great benefit in virtual environments as well as physical environments, although not all layering solution support physical/well connected desktops. It should be noted that some layering solutions also try to manage OS layers. Our methodology (Liquidware Labs FlexApp) is to separate the two. Base Image Management should be simplified by layering the applications on top of your best image managed the more traditional and efficient way.

2) Streamline the management of application updates. Imagine updating one installation of an application and instantly making that available to all Windows desktops on your enterprise. WIth layering, there is zero downtime to install applications and it gives you huge cost/time savings from a manual installation or even Microsoft SCCM.

3) Package/Install Once - This is related to the above but imagine one installation of an app going across mixed delivery platforms - VMware/Citrix/Amazon WorkSpaces/Physical - now also imagine it working for all OS versions from Windows 7 forward through to 10 as well as Server OSs (some layering solutions do this and some don't). That's a huge time savings for migrations and disaster recovery scenarios. 

4) App Virtualization such as Microsoft App-V and VMware ThinApp have limitations when it comes to apps with drivers and services or apps that need to play well with other apps. Most application layering solutions overcome this because they don't run as isolated apps, therefore they have a higher degree of success, usually MUCH higher. 

Jason E. Smith - Liquidware Labs, the source for FlexApp Application Layering