ICA

Update 2015-04-28: Citrix provides the limited release hotfix ICATS760WX64009 that fixes this issue. More information below. During the research for my session about the XenApp 7.6 logon process, to be presented at Citrix Synergy and BriForum London, I noticed that the logon to my XenApp 7.6 lab server was taking a bit long. Longer, in fact, than the combined durations of the main logon phases user profile loading, group policy processing, logon script execution and shell startup. Much longer. Also much longer than on an otherwise similar XenApp 6.5 machine.

How do you programmatically determine if an application is running in a session accessed over a remoting protocol (i.e. ICA aka HDX or RDP)? It may be Citrix’ strategy to completely hide the fact that a session is remoted - which makes sense in many ways - but in some cases developers simply need to know in order to optimize their applications. It is surprisingly difficult to find official documentation about this. Here is what you need to know.

I had to troubleshoot a case where it suddenly was not possible any more to connect via ICA/HDX to freshly installed Windows 7 VDI machines. As it turned out, the root cause was a combination of Microsoft disabling legacy technologies and Citrix relying on them.