Citrix 3 2 XenDesktop architecture

Building a XenDesktop site starts with installing the Delivery Controller and its management console, Citrix Studio. The Delivery Controller needs a place to store its settings and configuration, so a database is added (SQL Server Express works fine for a lab). Once these two components are in place, you bring in the Citrix License Server, ideally on its own virtual or physical machine, so users have access to the features and editions they have actually paid for.

With those three core components ready, you can begin to address use cases. The first popular case is VDI: it requires a VDA, a hypervisor and your master VMs, delivered through either Provisioning Services (PVS) or Machine Creation Services (MCS). The second use case is hosted shared apps and desktops on a server OS: install the VDA on a supported server OS and publish applications and shared desktops. A third case is hosted application on a desktop OS: useful when an application does not run on a server OS; you publish it from Windows XP, 7 or 8 with a one-to-one VM-to-user ratio.

Other key components

  • Remote PC — install a VDA on an existing physical PC for remote access.
  • Citrix Director — the troubleshooting console for support staff to monitor sessions, machines and help desk calls.
  • StoreFront — internal users hit a StoreFront web interface to enumerate their resources.
  • NetScaler Gateway — for users coming from outside the firewall, NetScaler acts as a secure reverse proxy. Other gateways can be used, but NetScaler integrates very tightly with Citrix and adds features that enhance the user experience.
  • HTML5 Receiver — when no native Receiver is installed on the endpoint, users can still access resources through a modern browser.

All these pieces are tied together by the Delivery Controller, which decides which user goes where, which VDA is available and which server has the lowest load. We continue in the next video with the detailed list of XenDesktop components.

Summary

XenDesktop architecture comprises three core components: the Delivery Controller managing user connections and resource allocation, a SQL Server database storing configuration and settings, and a License Server providing access to licensed features and functionalities. The platform supports multiple deployment models including Virtual Desktop Infrastructure (VDI) with provisioning services, shared server applications for centralized delivery, assigned desktops, and remote PC access for physical machines.

Key points

  • The Delivery Controller is the foundational management component that orchestrates all user connections, resource availability, and system configuration
  • A SQL Server Express database stores essential configuration parameters and settings required by the Delivery Controller
  • The License Server is mandatory to unlock Citrix features and technologies; placing it on dedicated infrastructure is a best practice
  • VDI deployments can use Provisioning Services or Machine Creation Services; VMs require local virtual hard disks for cache storage with Provisioning Services
  • Shared Server applications reduce infrastructure costs by allowing multiple users (100+) to access applications installed on a single server, avoiding per-user VM provisioning
  • Remote PC Access centralizes management of physical machines through Citrix agents and Citrix Director console for support staff troubleshooting

FAQ

What are the three mandatory components of XenDesktop architecture?

The Delivery Controller (manages connections and resources), a SQL Server database (stores configuration and parameters), and a License Server (activates features and ensures compliance).

What is the difference between VDI and Shared Server applications?

VDI provisions individual virtual machines to users via Provisioning Services or MCS. Shared Server applications allow 100+ users to access a single application instance on a server, eliminating the need to provision dedicated VMs per user.

How do external users access XenDesktop resources from outside the firewall?

NetScaler (the recommended reverse proxy) is deployed for secure external access. Alternatively, users can access resources via HTML5 or a web browser without requiring a Citrix client.