I was involved in a big project migrating a complex stack from Windows XP to Windows 7 x86, and got scared this !@#$ out of me.
The stack communicated to WebSphere MQ on AS/400 from Windows, and on the Windows side of things consisted of a UI developed in in Cool:Gen, a C interface to a Delphi DLL, which takes care of the communication to WebSphere MQ.
Digression:
This all was histerically grown. In the beginning (early to mid 90s last century) it was a big Borland Pascal/Turbo Pascal application – running on DOS, Windows 3.1x, Windows 95 and OS/2 2.x/3.0 – that talked over a propriatary layer over SNA to AS/400.
The vendor of that layer didn’t respond to a request for Windows NT 4.x compatibility, and meanwhile some client applications were about to be developed in Delphi.So in 1997/1998 – together with a great AS/400 software developer – I wrote a SNA based APPC/CPI-C communication layer in Delphi 3 that could be accessed from both Turbo Pascal (using a file based interface) and Delphi (using an object interface).
The DOS interface was an executable around the Delphi interface, which was a set of classes.Delphi part
The Delphi part of the DOS interface was centered around FindFirstChangeNotification/CreateProcess combined with MsgWaitForMultipleObjects/WaitForSingleObject to make the waiting as efficient as possible.
DOS part
DOS part
The DOS part of the Delphi interface was centered around this piece to make waiting efficient:
[sourcecode language=”Pascal”]
asm
int $28
mov ax, $1000
int $15 { DESQview/TopView give up time slice }
mov ax, $1680
int $2F
end;
[/sourcecode]Thanks to the RBIL: Ralf Brown’s Interrupt List (there are now multiple HTML versions of it), it makes use of these tricks so DOS applications can efficiently wait : Read the rest of this entry »
