Layering can seem a complicated concept at first; once you look under the hood though, the rationale, benefits, and purpose all becomes clearer.
A layer is a container which allows for the storing of file systems, objects, and registry entries which are all unique to that layer. For example, an ‘Application Layer’ is a layer where the files and registry entries that have been added, changed, or even removed during the application install, uniquely reside.
Layering is an integration technology. The layers all come together and are integrated for the end User. This gives a stronger user experience, since to the User, the application runs the same way it always has for them.
So how does Citrix use this technology?
The goal is to have everything inside of a layer. You’ll make a layer for your OS, your simple Apps, your complex Apps, the VDA, even User Data.
This enables you to manage one instance of the App and the OS without having to support multiple copies of the same OS version, and multiple copies of applications, commonly known as image sprawl, which is common using traditional image management solutions.
There is a high level of compatibility with Citrix apps because App Layering provides two delivery methods; Pre-Boot, which are Layered Images, and Dynamic Allocation, which is a type of Elastic Layering.
There are four types of layers in a Citrix App Layer environment:
- Personalization layer (now called User Layers). At its heart, the personalization layer is simply a read/write disk. Any changes that the user makes can be stored here, from something as simple as a favorites list, to something as complex as an installed app or plugin. The personalization layer is mounted and not streamed so that things like the Outlook Data File can be delivered to users quickly on login.
- Application Layers. Application Layers will be the majority of layers in your environment. These layers contain the registry and filesystem information for one or more apps. You don’t necessarily have to put 1 app per app layer, although it is generally advised. You can have 3-4 apps in one layer if it makes sense for you and your infrastructure.
- Platform Layer. Platform layers are special layers only applied during the layered image creation. These layers will contain drivers for specific environments, so you’ll find Hypervisor tools, Provisioning Tools, and Broker Tools here.
- OS layer. This layer is the foundation of the whole environment. This layer is typically clean except for the Citrix App Layering Tools, and in some environments the Hypervisor tools.
Why should I consider App Layering?
App Layering allows you to accelerate workplace mobility.
Traditional application management solutions have caused many IT problems, from having to repackage apps for every platform to being incompatible with the cloud – not to mention the strain on IT budgets. App Layering solves these challenges and offers IT the best way to separate apps from the underlying operating system, so they can be managed once and delivered from anywhere, to any device. To learn more about Citrix App Layering https://www.citrix.co.uk/virtualization/app-layering.html