Remko Weijnen's Blog (Remko's Blog)

About Virtualization, VDI, SBC, Application Compatibility and anything else I feel like

imageI 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.confwith the following contents:

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Google Earth fix for XenApp, RDSH & Horizon

Google Earth LogoBoth 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.

 

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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:

De compoort lezer staat uit

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

Er staat geen compoort in het register. Registreer eerste de juiste compoort

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The case of the COM Port Redirection

SecutestOne 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:

image

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Change Tab Order in an Executable

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:

image

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:

image

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.

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License Check fails on Citrix XenApp

imageToday 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:

image

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.

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  • Filed under: Citrix
  • 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

     

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    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:

    image

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

     

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    imageI 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:

    image

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    Excel 2010 multi-threaded calculation

    Excel 2007 IconI was just browsing through the Options tab in Excel 2010 when I noticed the following setting:

    image

     

    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.

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  • Filed under: General
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