Layering is everywhere. There will definitely be a tiered cake at a wedding. People who go out in the cold winter will definitely wear a lot of three layers inside and outside to keep warm. The earth itself is also made up of many layers. So it's only natural that layering becomes part of application virtualization.

Application layering may still be a somewhat niche technology, but it has gained attention for its wide range of uses. Because application layering allows some IT managers to pinpoint users who need specific applications and deliver applications directly to them.

As this emerging technology is still evolving, IT administrators must understand how it works and compare it to the current mainstream application virtualization on the market.

What is application layering?

Application layering is a method of delivering virtual applications to end users based on different criteria such as grouping or geographic location. Application layering helps administrators deliver the right applications to the right users. Applications run on different layers than virtual desktops. Administrators can modify, upgrade, and manage applications independently of the base image of the virtual desktop. As a result, administrators need to deal with fewer base images, and even all virtual desktops only need to use a single golden image.

Applications delivered through layers interact with the operating system as if the applications were installed locally. Application layering is ideal when virtual applications must interact directly with the user's device, kernel drivers, or other applications.

How App Layering Works

Each application layering tool is unique, but all follow a basic three-tier architecture. The bottom layer is the main hard disk of the virtual desktop, which is used to host the virtual desktop operating system. The middle layer is used to support application operation, including providing binary files, registration codes, drivers, etc. The last layer carries the user's profile data and is decoupled from the operating system.

Application layering can be likened to a sandwich. The bottom layer and the user data layer are the bread, all sandwiches have. The middle layer includes toppings, which are related to the specific sandwich.

Standalone applications are usually layered on their own, allowing administrators to deliver specific applications to specific users. As a result, IT administrators may layer more than three layers of applications delivered to specific users, including the bottom layer, the middle layer, and the user configuration layer for the applications the user uses.

How is application layering different from application virtualization?

VDI managers should not view application layering as a replacement for more convenient application virtualization tools such as Citrix XenApp or VMware ThinApp. Virtualization tools can deliver applications that are incompatible with the underlying operating system, but application layering is OS-dependent.

Another difference is that application virtualization tools such as XenApp and ThinApp encounter process isolation problems, and each application runs completely independent of the operating system and other applications. Therefore, there is no direct communication between applications.

What are the best app layering tools on the market?

There are three main products in the application layering market: VMware App Volume, Liquidware Labs FlexApp, and offerings from Citrix.