Citrix XenDesktop has different delivery technologies for the various desktop types:
n Pooled desktops are delivered via the Citrix Provisioning Server and Desktop Delivery Controller (connection broker)
n Assigned desktops do not use Citrix Provisioning Server, but they use Desktop Delivery Controller
Desktop Delivery Controller
Desktop Delivery Controller is a connection broker.
The XenDesktop Controller provides the link between the web interface and the XenDesktop site. The controllers authenticate users, enumerate resources for the users, and direct user launch requests to the appropriate virtual desktop. The controllers manage and maintain the state of the XenDesktop site to help control desktop startups, shutdowns, and heart beats. The controllers constantly query and update the SQL database with site status, allowing controllers to go offline without impacting user activities. It is recommended that at least two controllers be deployed per XenDesktop site to provide high availability. As the site grows, additional controllers might be required if the allocated CPU cannot service the user requests fast enough.
Provisioning Services
Provisioning Services provide images to physical and virtual desktops. Desktops use network booting to obtain the image, and only portions of the desktop images are streamed across the network, as needed. Provisioning Services use similar identity management functionality used by the Machine Creation Services. Provisioning Services require additional server resources, but these can be either physical or virtual servers, depending on the capacity requirements and hardware configuration. Also, Provisioning Services do not require the desktop to be
virtualized, because Provisioning Services can deliver desktop images to physical desktops. Citrix Provisioning Server is a streaming technology that can be used to provide multiple virtual desktops from a single copy of an operating system in the storage back-end. It provides the same image management capabilities as VMware Linked Clones, even though they use
different technologies. Similar to Linked Clones, the limitation is that it cannot be used for assigned desktops.
Licensing Server
The Licensing Server is responsible for managing the licenses for all of the components of XenDesktop 5. XenDesktop has a 90-day grace period, which allows the system to function normally for 90 days if the license server becomes unavailable. This grace period offsets the complexity involved with building redundancy into the license server. This service is minimally impacted and is a prime candidate for virtualization.
Virtual Desktop
XenDesktop provides a powerful desktop computing infrastructure that is easy to manage and support. The open architecture works with your existing hypervisor, storage, Microsoft, and system management infrastructures, with complete integration and automation via the comprehensive software development kit (SDK).
Virtual Desktop Agent and Desktop Receiver
Citrix Receiver, a lightweight universal client, enables any PC, Mac, smart phone, tablet, or thin client to access corporate applications and desktops—easily and securely.
XenApp
Citrix application virtualization technology isolates applications from the underlying operating system and from other applications to increase compatibility and manageability. As a modern application delivery solution, XenApp virtualizes applications via integrated application streaming and isolation technology. This application virtualization technology enables applications to be streamed from a centralized location into an isolation environment on the target device. With XenApp, applications are not installed in the traditional sense. The
application files, configuration, and settings are copied to the target device and the application execution at run time is controlled by the application virtualization layer. When executed, the application run time believes that it is interfacing directly with the operating system when, in fact, it is interfacing with a virtualization environment that proxies all requests to the operating system.
XenApp is unique in that it is a complete system for application delivery, offering both online and offline application access through a combination of application hosting and application streaming directly to user devices. When users request an application, XenApp determines if their device is compatible and capable of running the application in question. The minimum requirements of a target device are a compatible Windows operating system and appropriate Citrix client software. If the user device meets minimum requirements, then XenApp initiates application virtualization via application streaming directly into an isolated environment on the user device. If the user device is not capable of running a particular application, XenApp initiates session virtualization.
Application Streaming Profiler
The Citrix Streaming Profiler is the software component that is required to create the
application packages. Just like other application virtualization solutions, this component should be installed on a clean machine where only the necessary files and settings are saved within the record process. The installation of the software component is easily done by following
instructions from the wizard. When done, you are ready to create your first Application Profile. It is best practice to use a virtual workstation for these activities, so you can create a snapshot of the state before you start the profiling process. Citrix is updating this software component on a regular basis, so, when building the virtual machine, it is a good idea to check the Citrix
© 2012 Cisco Systems, Inc. Cisco Data Center Solution Architecture and Components 1-93
Summary
This topic summarizes the primary points that were discussed in this lesson.
© 2012 Cisco and/or its affiliates. All rights reserved. DCUCD v5.0—#-38
• Data center applications differ in their purposes and their characteristics. • Server virtualization enables better server physical resource usage by
hosting multiple virtual machines on the same host.
• Virtual machines provide flexibility, scalability, and reliability benefits over physical servers.
• The desktop virtualization solution delivers virtual desktops over the network.
• The operating system and applications of the desktop can be virtualized independently.
References
For additional information, refer to these resources:
n http://www.cisco.com/en/US/netsol/ns340/ns394/ns224/index.html n http://www.cisco.com/en/US/netsol/ns743/networking_solutions_program_home.html n http://en.wikipedia.org/wiki/virtualization n http://hadoop.apache.org/ n http://www.citrix.com/lang/English/home.asp n http://www.vmware.com/products/vsphere/mid-size-and-enterprise-business/overview.html n http://www.vmware.com/products/view/overview.html n http://www.microsoft.com/en-us/server-cloud/windows-server/default.aspx n http://www.microsoft.com/en-us/server-cloud/windows-server/hyper-v.aspx