XenApp on Remko's Blog

Where does the Citrix Linux VDA store settings?

Thu, 23 Mar 2017 17:02:44 +0000

I recently (well today really) started playing with the Citrix Linux VDA. I took Ubuntu to test because I happen to like Ubuntu.

I didn’t get it to work correctly right away though and during troubleshooting I wanted to know where the VDA is storing it’s settings.

I found the following file /etc/xdl/ctx-vda.conf with the following contents:

Google Earth fix for XenApp, RDSH & Horizon

Mon, 20 Feb 2017 20:26:51 +0000

Both Google Earth and Google Earth Enterprise do not work correctly for multiple users on shared Hosted Shared Desktops (I still prefer to call it Server Based Computing but that’s likely because I’m an oldtimer).

Problem summary
So let’s look at the actual issue: the first user on a server is able to launch Google Earth but for any subsequent users on the same server Google Earth fails silently.

Problem details
Google Earth uses various synchronization objects such as Events and Mutexes but registers those in the \Global namespace instead of the \Local namespace.

Redirect Registry by Modifying .NET Executable

Thu, 30 May 2013 16:18:23 +0000

Yesterday I was troubleshooting an application that was migrated to Citrix XenApp.

The application is able to use a high precision scale which is attached to the client pc's com port. This com port is redirected to XenApp.

While testing users reported several issues, let's have a look at them.

Error configuring COM Port
Within the application the comport to which the scale is connected must be configured:

After pressing "Registreer" to register the new com port the following error message was shown

The case of the COM Port Redirection

Mon, 11 Mar 2013 14:53:44 +0000

One of my colleagues asked me to assist in troubleshooting an application called SmartWare FM running on Citrix XenApp.

This application reads data from an external device called SECUTEST.

The device is connected to a COM port which is redirected to the XenApp session. In contrast to Microsoft Remote Desktop Services COM ports are not automatically redirected in XenApp but need to be mapped via eg a logonscript (NET USE COM1: \\Client\COM1:) or using UEM.

In my case the COM port was mapped with RES Workspace Manager:

Change Tab Order in an Executable

Wed, 02 Jan 2013 15:03:14 +0000

An application called Cardiology PACS was recently packaged for a Citrix XenApp environment. The functional tester reported a strange problem at the logon screen: after entering the username it was not possible to go to the password field with the TAB key.

This was a strange observation since I cannot imagine XenApp interfering with tab stops. So what was going on?

In the old situation the user was starting the application on his local pc. The application remembered the last username and pre-filled this, therefore the cursor was already in the Password field. The user simply entered his password and hit the Enter key:

On XenApp the Username field is not pre-filled because the last username is kept globally per machine. Therefore the user has to enter both the username and the password:

I tested the Tab key behavior in both situations and as I expected it didn’t work in both situations. This happens because the Tab Order has been messed up by the programmer (if you press Tab 9 times you do end up in the Username field).

Because this is something that would annoy me if I were the user I decided to fix it.

License Check fails on Citrix XenApp

Fri, 07 Dec 2012 16:30:07 +0000

Today I was asked to assist in getting an Excel Add-In to work on Citrix XenApp.

The application was packaged into a Thinapp by one of our package engineers.

However when testing the Add-In on Citrix XenApp the following message appeared:

Apparently this application does a license check that fails when run from another server (how bad).

Disclaimer
Before we go on: I would like to make clear that my goal is not to be able to use an application without license. I am just trying to make it work within the customer’s environment.

Screen flickering with PowerPoint 2010 on Citrix XenApp

Fri, 30 Nov 2012 14:18:22 +0000

Within half an hour of writing the article "Application causes Screen Flickering in Citrix XenApp Session" I got a message that the hotfix in that article also fixes a similar problem in PowerPoint 2010.

Office 2010 uses hardware acceleration for displaying images and when this is enabled (which is the default) you will see constant screen flicker when you try to display a presentation with Images on Citrix XenApp (Server 2003):

Screen Flickering when running WPF Applications on Citrix XenApp

Application causes Screen Flickering in Citrix XenApp Session

Fri, 30 Nov 2012 13:28:54 +0000

Yesterday I was asked to troubleshoot an interesting issue with an application running on Citrix XenApp.

Environment
This customer is running Citrix XenApp 5 on Windows Server 2003 (x86). On the Client Side the Online Plugin version 12.3 is used.

The Problem
When this particular application was active the screen was flickering and black blocks appeared at seemingly random places. Further more it was not possible to resize the window:

My experience is that display issues are often related to either HDX Flash Redirection (offloading flash to the client) or the Multi Monitor hook.

Modify VB Executable to force Taskbar Button

Sat, 04 Aug 2012 11:07:18 +0000

I had to troubleshoot an application that was published with Citrix XenApp. The problem with this application was that it didn't have an button/icon in the taskbar and the window would sometimes disappear.

I noticed that this (cr)application was written in Visual Basic, so I decided to run it through a decompilation tool.

The decompiler was able to list the forms used in the Application:

Excel 2010 multi-threaded calculation

Fri, 08 Jun 2012 13:21:19 +0000

I was just browsing through the Options tab in Excel 2010 when I noticed the following setting:

This feature was introduced in Excel 2007.
In the default settings, multi-threaded calculation is Enabled with "Use all processors on this computer".

On a physical desktop this would be the preferred setting since it will make formula calculation as fast as possible.

Cookie Error on Citrix XenApp

Thu, 29 Mar 2012 10:02:10 +0000

A user reported that the following error while visiting a website on a Citrix XenApp server:

I tried adding the site to the Trusted Sites List and adding the url to the Per Site Privacy list:

But this didn't work, but I noticed that the site was "flickering" a lot so I suspected that HDX Flash Acceleration was the problem.

Session freeze when starting Excel

Mon, 20 Feb 2012 15:42:25 +0000

Environment
Windows 2003 Enterprise (32 bit), Citrix XenApp 5, RES Workspace Manager 2011, McAfee VirusScan Enterprise 8.7.0i.

Problem
When a opening an Excel workbook from Sharepoint the whole session freezes.

I asked the user to open an Excel workbook from Sharepoint and I noticed the following popup:

So my first thought was that the user somehow clicked this message to the background and IE was waiting for a response.

The case of the Slow Xerox Universal Print Driver

Wed, 04 Jan 2012 22:54:29 +0000

Earlier this week I was asked to investigate a problem with the Xerox Universal Printer Driver. Users complained that printing to a Xerox printer was much slower than printing to an HP printer.

I received a reference document from a user, a rather complex Excel sheet. When selecting multiple tabs it took almost a minute to generate a print preview in Excel 2007 running on Windows 2003 with XenApp 5.

I was aware of a bug in the Xerox Universal Driver where almost 9.000 files were copied into the user's profile directory (I wrote about that in an earlier post). But this seemed to be another problem.