Communication flow during the different stages of the Citrix XenApp/XenDesktop logon process
1. The user device submits credentials to the Web Interface (WI) or StoreFront (SF) web server.
2. For StoreFront, the credentials are verified directly to a Domain Controller . The SF then passes the validation over to the Citrix Delivery
Controller (DC) to begin resource enumeration. For Web Interface, the username and password is passed to the DC.
3. The DC then queries a Domain Controller with the end user’s credentials to verify user authorization.
4. Next, the DC then queries the site SQL database for the end user’s assigned Delivery Groups. The resources defined by the Delivery Groups are sent to
the WI or SF server and presented to the user.
5. When the User clicks on one of the resource icons to start a desktop or application session, using the Delivery Group obtained from the database, the DC
queries the hypervisor about the status of resources within that group.
6. The DC identifies to Web Interface/StoreFront the virtual machine it assigned for this particular session.
7. The Web Interface/StoreFront creates and sends an ICA file to the Citrix Receiver pointing to the virtual machine that hypervisor identified.
8. The Citrix Receiver establishes an ICA connection to the specific virtual machine that the DC allocated for this session.
9. The Virtual Delivery Agent (VDA) verifies the license file with the DC.
10. The DC queries the Citrix License server to verify that the end user has a valid ticket.
11. The DC then passes session policies to the VDA, which in turn applies session policies to the virtual machine. Profile loading, GPO processing, loading of
scripts, drivers, printers, etc. all occur at this stage.
12. The Citrix Receiver displays the selected resource to the end user.
