installscript register ASP.NET 1.1 (if not registered)

For some reason, one of our ASP.NET 1.1 based products is often installed on machines where ASP.NET 1.1 is installed on the machine, but not registered with IIS. (They typically have 2.0 installed and registered though.)

To get around this issue, I have created the following InstallScript function.

function RegisterAspDotNet(hMSI)
 STRING svPatAddFolderIconszApplicationPath;
 NUMBER nvType, nvSize, nIsFlag;            
begin                                                  
//Check the registry to see if ASP.NET 1.1 is  installed 
//We'll be looking in the HKLM hive
RegDBSetDefaultRoot(HKEY_LOCAL_MACHINE);

//initialise to be sure of what started with 
svPath = "";
           
//Try and read a value from the registry, which will exist if it is installed and registered
RegDBGetKeyValueEx("SOFTWARE\\Microsoft\\ASP.NET\\1.1.4322.0", "Path", nvType, svPath, nvSize);
          
//If path key does not exists, ASP.NET 1.1 is not registered with IIS           
if (svPath == "") then  
 //Check it exists
 nIsFlag = FILE_EXISTS;
 szApplicationPath = WINDIR ^ "\\microsoft.net\\framework\\v1.1.4322\\aspnet_regiis.exe";
 //To ensure that the path or filename is correctly enclosed in quotation marks,
 LongPathToQuote(szApplicationPath,FALSE);
 //Check if the exe file exists
 if (Is (nIsFlag, szApplicationPath) == TRUE) then         
   //Register with IIS
   LaunchAppAndWait(szApplicationPath, " -i", WAIT);       
 endif;     
endif;

end;

I run this as a custom action in the Install UI Sequence after LaunchConditions. (If you're not doing a UI install, you really should check the software requirements first!)