To virtualize server-based applications, Citrix XenApp™ abstracts the user interface (logical layer) from the application processing (physical layer) that occurs on a centralized, secured server. This technology is ideal for delivering client/server applications because it eliminates the complexities of deploying, managing, updating and securing a vast array of client software on each individual user’s access device. Instead, a single instance of the client application is installed on XenApp within the secure confines of the datacenter. The application executes entirely on the server, while its interface is displayed on the user’s device. Application delivery can be enabled for any user, regardless of device, network or location.

Presentation virtualization abstracts the user interface
from the application logic

XenApp delivers applications to users through the Independent Computing Architecture (ICA®), a presentation-layer protocol by which servers and client devices exchange data in a server environment to separate an application’s logic from its user interface. In addition to the ICA protocol, XenApp also supports the Microsoft Terminal Services Remote Desktop Protocol (RDP).

As an application runs on a server, XenApp intercepts the application’s display data and uses the ICA protocol to send this data to the ICA client software running on the user’s device, increasing application performance. The ICA protocol encrypts and transports an application’s interface from the server it is running on to the user’s client device for display. It then returns the user’s input, mouse-clicks and keystrokes, to the application on the server.

A centralized architecture for servers simplifies management and provides users with remote application access

All applications are stored in the Application Hub, and the application user interface (UI) is delivered to the user virtually by passing only screen pixels, keystrokes and mouse actions between the client and server over the network. This is done without the need for pushing actual data or software, increasing security—especially for users connecting from outside the organization’s network.

Presentation virtualization technology, which enables both client and server components running together in the datacenter, typically results in less bandwidth use and faster application performance. During this process, 100% of the application’s logic (for both client and server components) executes on the server and, regardless of whether it is Windows, UNIX, Java™ or Web-based, the application can now be accessed from any device or location over any network.

With XenApp presentation virtualization technology, users access applications running on the server the same way they would if the applications were running on the local device (e.g., through desktop icons or the start menu) making this process transparent. Meanwhile, IT administrators benefit from a far more cost-effective, easy-to-manage and secure method for deploying and managing business applications.