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Citrix Application Layering explained

Geschreven door Redactie Craft - 26 september 2017

Redactie Craft
At Summit 2017, Citrix announced the acquisition of Unidesk, the pioneer of the groundbreaking Windows application packaging and management technology known as layering. What makes Citrix Application Layering so unique? Only Citrix Application Layering offers full-stack layering technology, which enhances compatibility by layering the entire Windows workspace as modular virtual disks, including the Windows operating system itself (OS layer), apps (app layers), and a writable persistent layer that captures all user settings, apps, and data. With its Unidesk 4.0 architecture, Citrix customers will be able to leverage the most scalable and feature-rich app-layering solution that simplifies the transition to the cloud, with the need to only manage a single app image across both on-premises and cloud-based deployments. On the following pages, I will talk about Citrix Application Layering and explain the different deployment models and their respective layering technologies.

Citrix Application Layering offers 2 deployment models.

With Layered Image, you have multiple images, like Windows 2012, XenApp, Office and Adobe Reader for example, which you can bring together in one layered image. You can see this as a “golden” disk.

Citrix Layered Image

Elastic layers are layers (images) that become active when users log in. This means the layers are accessed based on access rights, like being a member of a domain group for example. The layers are accessible from a simple network share.

Elastic layers

Layered images are layers chosen by the Admin and combined into a “template”. The most common things you’ll find in such a template are OSs, hypervisor drivers, print drivers, Office, Adobe Reader, antivirus programs, etc. This image template will then be published and, after publishing, a new virtual disk is created and layers composited together into a native image.

Layered images

Citrix Application Layering uses a Platform Connector, which you can use to communicate with different hypervisors and different provisioning mechanisms in order to put the appropriate drivers in the image and copy this to the target platform.

Citrix Creating a Layered Image

This means that when you have a multi-hypervisor environment or if you are thinking of migrating your environment to Azure or a hybrid environment you don’t have to re-image or rebuild your whole environment: you can use the same OS and application layers and point them to a new platform. Citrix Application Layering will build the new image and deploy it to the new platform.

Citrix Layered Image Cross Platform Mgmt

As I previously mentioned, elastic layering is a way of offering applications that will be assigned when a user logs in. Elastic layering has more features. Elastic layers are published into a repository (UNC path) and the user connects to that repository during login. It is then checked whether the user is a member of any groups with access to an application in this repository. This is all managed by the layering services. If a user has access to an application the VHD will be mounted and the application(s) will be presented on the desktop. Because elastic layering is active when a user logs in, you can assign different applications (layers) to different users.

Citrix Elastic Layering

Given that elastic layering is just a simple UNC path, you can easily use it in a DR/enterprise environment. Just make sure you have multiple UNC paths in the different locations. This means that you will need to have the same shared folder in the DR environment or in the Azure cloud; simply copy the repository in Datacenter 1 into Datacenter 2. The layers will be mounted as read-only VHDs. Use file replication to keep the repositories up to date. This is the same trick you use when you use Azure in a DR environment, for example. Copy the repository from the Datacenter 1 environment to the Azure environment and enable a file replication mechanism between the 2 repositories.

Citrix Elastic Layering in DR/the Enterprise

Well, that is, in short, what Citrix Application Layering can do. Citrix has made Citrix Application Layering available to all of their products, with the exception of XenApp Secure Browser. It is available for XenApp Advanced, XenApp Enterprise, XenApp Platinum, XenDesktop VDI, XenDekstop Enterprise and XenDesktop Platinum.

“But where is the cloud?” I hear you say. Regarding cloud use Citrix has the following to say:

“Citrix App Layering is a cloud service offering for all customers. Customers using the XenApp and XenDesktop Service are entitled to platinum-level features, including all Citrix App Layering capabilities. Citrix App Layering also allows you to access the management console within Citrix Cloud (currently in Labs/preview), making it even easier to get started with the technology.”

Personally, I can only see advantages and no downsides to creating software packages that are independent of any OS version or hypervisor version or brand.

Want to know more about Craft, the development programme for IT professionals? Check out the Craft website!


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