Does anyone know about issues between Citrix and Delphi 2007 applications? (And perhaps other development languages?)

Question

The situation is simple. I\'ve created a complex Delphi application which uses several different techniques. The main application is a WIN32 module but a few parts are devel

Answer 1

Many of our customers use our Delphi applications on Citrix. Generally speaking, it works fine. We had printing problems with older versions of Delphi, but this was fixed in a more recent version of Delphi (certainly more recent than Delphi 2007). However, because you are now running under terminal services, there are certain things which will not work, with or without Citrix. For example, you cannot make a local connection to older versions of InterBase, which use a named pipe without the GLOBAL modifier. Using DoubleBuffered would also be a really bad idea. And so on. My suggestion is to look for advice concerning Win32 apps and Terminal Services, rather than looking for advice on Delphi and Citrix in particular. The one issue which is particular to Citrix that I'm aware of is that you can't count on having a C drive available. Hopefully you haven't hard-coded any drive letters into your code, but if you have you can get in trouble.

Answer 2

There were some issues in the past with Published Delphi Applications on Citrix having no icon in the taskbar. I think this was resolved by the MainFormOnTaskbar (available in D2007 and higher). Apart from that there's not much difference between Terminal Server and Citrix (from the Application's perspective), the most important things you need to account for are:

• Users are NEVER administrator on a Terminal or Citrix Server, so they no rights in the Local Machine part of the registry, the C drive, Program Folder and so on.
• It must be possible for multiple users on the same system to start your application concurrently.
• Certain folders such as the Windows folder are redirected to prevent possible application issues, this is also means that API's like GetWindowsFolder do not return the real windows folder but the redirected one. Note that this behaviour can be disabled by setting a particular flag in the PE header (see delphi-and-terminal-server-aware).
• Sometimes multiple servers are used in a farm which means your application can run on any of these servers, the user is redirected to the least busy server at login (load balancing). Thefore do not use any local database to store things.
• If you use an external database or middleware or application server note that multiple users will connect with the same computername and ip address (certain Citrix versions can use Virtual IP addresses to address this).

Answer 3

Generally speaking, your application needs to be compatible with MS Terminal Services in order to work with XenApp. My understanding is that .NET applications are Terminal Services-compatible, and so by extension should also work in a Citrix environment. Obviously, as you're suffering some problems, it's not quite that simple, however.

There's a testing and verification kit available from http://community.citrix.com/citrixready that you may find helpful. I would imagine the Test Kit and Virtual Lab tools will be of most use to you. The kit is free to use, but requires sign-up.

Answer 4

Security can be an issue. If sensitive folders are not "sandboxed" (See Remko's discussion about redirection), the user can break out of your app and run things that they shouldn't. You should probe your app to see what happens when they "shell out" of your app. Common attack points are CHM Help, any content that uses IE to display HTML, and File Open/Save dialogs.
ex: If you show .chm help, the user can right-click within a help topic, View Source. That typically opens Notepad. From there, they can navigate the directory structure. If they are not properly contained, they may be able to do some mischief. ex: If they normally don't have a way to run Internet Explorer, and your app has a clickable URL in the about box or a "visit our web site" in the Help menu, voila! they have access to the web browser. If unrestrained, they can open a command shell by navigating to the windows directory.