Exporting applications and desktops to a remote screen isn’t a new concept. From days preceding even UNIX/X Window System, IT has been able to deliver applications and desktops to end users. However, the real renaissance for app and desktop delivery started when users were able to connect to their Windows apps/desktops from any device over any network.
Independent of vendors, there are several different ways for IT to deliver apps and desktops to their end users, each delivering a different set of benefits. This article discusses some of the popular options IT can utilize to deliver virtualized applications and desktops to the end user and the functions of each:
Hosted Shared Desktops (HSD)
HSDs serve desktops from a single (shared) VM running a server-based operating system to multiple end-users. HSD represents the majority of the deployments supporting end users and is also often called out as Server Based Computing (SBC).
There is an additional category of software that delivers application virtualization. Here, the application is encapsulated from the underlying operating system on which it is executed. Virtualization in this case means encapsulation and not running on a hypervisor. This allows for different versions of the same application or mutually exclusive applications to co-exist without having to natively install them. Microsoft App-V and VMware ThinApp are options for application virtualization.
Hosted Virtual Desktops (HVD)
HVDs allow each end user to be served by his or her own individual desktop, typically running a desktop OS. They are becoming increasingly popular in environments requiring full feature desktops.
There are additional factors associated with virtualized desktops. IT administrators can provision personal/persistent desktops or pooled/non-persistent desktops. In the former case, the end users get their own desktops to run and customize. User files can be stored within the virtual desktop itself, but they would have to be protected individually.
The other “pooled” scenario deals with users logging into one of the desktops pulled from a pool of desktops. However, the user’s data typically isn’t stored within the virtual desktop. Customizations associated with the user’s desktop are maintained through the use of roaming profiles and folder redirection using a myriad of third-party user environments, or profile management tools.
Recently, another set of technologies around application layering has hit the app/desktop virtualization market called app and profile layering. These tools allow IT to create multiple virtual desktops via one golden image by choosing the appropriate layers of applications. This may even include a personalization layer so end users have their desktop settings when they log in, essentially creating personalized desktops from non-persistent pools.
Streaming and Local Desktops
Streaming and local desktops come in to play where end users run their desktops locally with OS images that are either streamed from a central location or presented locally. In certain cases, the virtualized desktop itself might run on top of another OS as a virtual machine. These types of desktops require significant bandwidth (when streamed), adequate compute on the end-user device to accommodate performance needs, and in the case of local virtualized desktops, additional software.
Streaming is finding a niche in the connected kiosk space where network connecting and computing at the end-point isn’t an issue and centralized management and control is needed. The local desktops are gaining traction in the PC/Mac space where there is a need to run other OSes locally (Linux on a PC running Windows or Windows on a Mac). This is seen in small/midsize environments lacking corporate-level resources for HSD or HVD/VDI.
Citrix, Microsoft and VMware have played key roles in the application and desktop virtualization and delivery space through innovation in the areas of protocol, virtualization software, including the broker and operating systems. Here are some of the components of the stack and the different options and vendors in each:
App/desktop virtualization software: This is the nerve center of any app/desktop virtualization solution. Offerings include Citrix XenApp/XenDesktop, Microsoft RDSH and VMware Horizon View. Citrix and VMware also deliver functionality in their respective stacks to help with provisioning of desktops, leveraging golden images and cloning.
Protocols: This is what is used to stream desktops from the server to the end-user device and capture end-user input. Protocols now also cover areas such as printer, USB for end-user peripherals and so on. Citrix has been the industry pioneer with its ICA and HDX technologies; Microsoft has the pervasive RDP and RemoteFX technologies; and VMware has PCoIP, which is licensed from Teradici and also supports RDP.
Client: This is the application running on the end-user device used to provide access to the desktop/application. Citrix has Receiver, Microsoft has RDC client, and VMware has View Client. End-users can now also use HTML-5 compatible web browsers to access their desktops and applications.
Networking and security: This is a critical, but often overlooked, component of the overall app/desktop virtualization and delivery stack with features like load balancing, encryption and network acceleration and firewalls. This application enables secure and highly available remote access to virtualized desktops and applications. Major players in this space include Citrix NetScaler and F5 Big-IP.
Server hypervisors: A variety of hypervisors can be used with the app/desktop virtualization software to run the end-user desktops including VMware vSphere, Microsoft Windows Server 2012 R2 (with Hyper-V) and the Nutanix Acropolis Hypervisor (AHV).
There is also the topic of underlying compute and storage infrastructure. If you haven’t already, it is definitely worthwhile to research the advantages of hyperconverged infrastructure for app and desktop virtualization, especially ones that come from using a linearly scaling web-scale architecture.
The app and desktop virtualization and delivery space has come a long way from where it used to be even five years ago. There are numerous vendors mentioned here that can help you simplify the process of app/desktop delivery. Do your research to evaluate what tools can help solve your organization’s needs.