XenApp Server: The Components and Infrastructure in a Typical Deployment

Organizations choose XenApp (now known as Citrix Virtual Apps) as it allows remote applications to be managed from and hosted on more secure datacenters. XenApp Server delivers virtual applications by extending Microsoft’s Remote Desktop Services protocol, particularly its Remote Desktop Session Host (RDSH) component. Thus, a supported Windows Server OS is required for hosting a XenApp Server. XenApp is also more cost-efficient because it does not require frequent hardware and OS upgrades.

What Is XenApp Used For?

Citrix XenApp allows virtualization of Windows-based applications for remote access from anywhere using any kind of device, regardless of OS. XenApp utilizes server-based computing (SBC) because it requires users to connect to applications hosted on a central server residing inside a datacenter, cloud-based or otherwise.

One advantage of XenApp is that users don’t have to worry about hardware compatibility. Authorized users can connect to the XenApp server and run the applications they need using their preferred devices.

While multiple users can simultaneously access virtualized, server-based applications, only authorized IT staff can virtualize applications. Thus, XenApp and similar solutions are better suited for fixed and routine work, as they do not offer users the ability to install applications on the server or their own devices.

How Is Citrix XenApp Server Typically Deployed?

XenApp runs on the proprietary FlexCast Management Architecture (FMA), a service-oriented architecture that allows for interoperability among various Citrix products.

The key elements in a typical XenApp server deployment, or site, include:

Delivery Controller: This component is responsible for the central management of the site. It is installed on at least one Windows server, although a site may have more than one Delivery Controller installed on separate XenApp servers for high availability. In the context of XenApp, the controller’s Broker Service reconnects users to applications.
Database: Each XenApp Server requires at least one Microsoft SQL Server database for storage of configuration and session information. There is a persistent connection between the controller and the site database. Aside from the site database, a XenApp deployment can have separate configuration and monitoring databases.
Virtual Delivery Agent (VDA): Each virtual machine (VM) hosting your applications has this installed. VDAs register the VMs to the controller, allowing your users to access the applications installed on the VMs.
Citrix StoreFront: The applications that your users can access are delivered through this component. It allows your users to access your applications on-demand and ensures that users have a consistent experience from any device.
Citrix Receiver: Now known as Citrix Workspace app, this component is installed on user devices for easy, self-service access to your applications. If users have non-supported devices, they can install a version that allows your applications to be run from any HTML5-compatible web browser.
Citrix Studio: This is the management console for your applications. It has wizards to help your administrators set up your XenApp Server environment. It also allows you to allocate and track your Citrix XenApp licenses.
Citrix Director: This component is used for troubleshooting any issues that may arise from your XenApp Server deployment.
Citrix License Server: This helps you manage your Citrix XenApp licenses through so-called license files. Each site must have at least one License Server.
Hypervisor or cloud service: This is the host for your site’s VMs. XenApp supports an array of hypervisors and cloud services.

Aside from the above-required components, a typical XenApp Server deployment may also require one or more optional components, including Provisioning Services, NetScaler Gateway (Citrix Gateway), and NetScaler SD-WAN (Citrix SD-WAN).

As seen from the list above, the typical XenApp Server deployment can be a complex task.

How Do Citrix XenApp Server and Other Components Handle User Connections?

In a typical Citrix XenApp Server deployment, user connections are handled in the following manner:

The controller authenticates and manages user access, brokers connections between users and their applications, and optimizes and load-balances user connections.
The controller has a Broker Service that is responsible for monitoring logged-on users and their locations and the session resources of each user. If users are disconnected from the XenApp Server, this same service reconnects them to the applications they were running previously.
VDAs connect user devices to applications, verify availability of Citrix licenses and apply configuration policies to user sessions.
Citrix Studio assigns applications to your users, and it allocates and tracks site licenses. You can also use Studio to allocate and track Citrix licenses for your site.
The Citrix License Server communicates with the controller to ensure that there are available licenses for your user sessions.

How Can I Diagnose Performance Issues with a Monitoring Solution?

You may run into performance issues when using XenApp Server. For example, slow-running XenApp Server-based applications brought about by users connecting via slow internet connections are a common complaint. Another problem may arise with users on older devices that may not support your deployed applications.

Although not guaranteed, a monitoring solution might help resolve performance issues in your XenApp Server deployment. Choose one that can review the channels through which your connections are running, the networks of your users, and the prevailing latency between your user devices and servers.

Reduce the Costs of Delivering Virtual Applications with Parallels RAS

Parallels® Remote Application Server (RAS) is an all-in-one solution that helps streamline application delivery across your network, enabling organizations to reduce IT complexity while increasing user productivity.

Parallels RAS manages and scales your IT infrastructures with RDSH, virtual desktop infrastructure (VDI) and Azure Virtual Desktop using a single pane of glass. It simplifies complex administrative tasks using smart wizards and automation tools that provide administrators with the most efficient path to application delivery.

Parallels RAS reduces your hardware footprint compared to other virtualization solutions, such as Citrix Virtual Apps and Desktops. When your organization needs to scale up, your per-user hardware expenses are lowered even more.

Check how you can use Parallels RAS to simplify your application delivery by downloading the trial.