With the release of Visual DataFlex 12.1, official support was added for Windows Terminal Services. In Visual DataFlex 2008 we have taken another step forward and added official support for Citrix Delivery Center.
Citrix Systems, Inc. is the global leader in application delivery infrastructure. Citrix Delivery Center is an enterprise level product family for remote/distributed computing and virtualization solutions, widely used to deliver applications to end-users.
Any Visual DataFlex application running on Citrix Delivery Center should be upgraded to version 2008 as soon as possible to take advantage of the enhancements outlined below.
Many Visual DataFlex developers have been running applications on Citrix for years. What’s new regarding Citrix in VDF 2008?
First and foremost, Data Access officially supports Citrix Delivery Center on Visual DataFlex 2008. Even though applications may have been working on Citrix for a long time, there was no actual platform support for it and there is a chance that parts of the applications were not always functioning as intended. Visual DataFlex 2008’s officially supported status means that the product has been fully and successfully tested on the Citrix Delivery Center platforms.
A number of improvements have been made in Visual DataFlex 2008 to specifically support all features of the Citrix Delivery Center product family:
User Counting
Visual DataFlex 2008 correctly counts users per session on Citrix Delivery Center. Running multiple applications in one session will count as one user. Two users running an application with the same login name but running in separate sessions will count as two users.
Among the problems encountered when running prior versions of Visual DataFlex applications on Citrix Delivery Center was user counting. Sometimes the user count did not correctly increment the number of users. Or, in some cases, the user count did not correctly decrement the user count allowing the system to support either too many or too few users.
Sentinel
Visual DataFlex 2008 uses a new sentinel that resides in the same process as the application. This enhancement solves the problem encountered in earlier versions of Visual DataFlex where the sentinel used in BusinessProcesses could crash the system when running in seamless mode, leaving only the sentinel running. Note that specifically using the old sentinel in your application can still cause problems. Even using Visual DataFlex 2008, you must switch to using the new sentinel. See "Status Panel Changes" in the "Compatibility and Upgrade Guide" help book for details.
Printing Issues
With pre-2008 Visual DataFlex,the most common problem area on Citrix Delivery Center was printer handling. In Visual DataFlex 2008, better error handling and a new set of WinPrint functions make sure that these problems never occur.
Background... Citrix has a built-in solution to enable seamless printing to the client printer. Problems arose with pre-Visual DataFlex 2008 applications when the client printer driver was not installed on the Citrix server. When the printer driver is not available on the server, Citrix Delivery Center uses a universal printer driver when printing to the client printer and, in many cases, this just did not work. In best case, only the session would crash. In worst case, the print spooler on the server would crash or the whole server would reboot. Visual DataFlex 2008’s enhancements resolve all known printing issues on Citrix Delivery Center.
Visual DataFlex 2008 now supports Citrix Delivery Center