Understanding sessions

Each time we establish a session with a XenApp server, we use a protocol called Citrix ICA (Independent Computing Architecture), created by Citrix. ICA uses virtual channels to transmit keyboard strokes and mouse movements, printing, video and audio traffic, and more from the client machine to the XenApp server and the response back from the XenApp server to the client machine.

ICA uses port 1494 by default, but when we enable the XenApp Session Reliability feature in our XenApp farm, port 2598 is used instead of port 1494.

When a client machine initiates communication to the XenApp server with an ICA client and the user is successfully authenticated against the XenApp farm, a session is created on the server. The session is the core of the XenApp experience.

We can find a session in three main states: active, idle, and disconnected.

Let's use an example to understand these states. Our friend William Empire at Brick Unit Construction starts a session in XenApp. He opens...