How can I make ADO database connections in 'TISAPIApplication` before processing incoming requests?

Question

TADOConnection is failing to connect in the application initialization section of Delphi ISAPI App (TISAPIApplication):

Application is built wi

Answer 1

The begin ... end or an initialization part of a dll is the Delphi equivalent to dllmain in C++. So the same restrictions apply including:

• Don't call CoInitialize
• Don't call COM functions

This implies that you cannot create an ADO connection.

Do you know all the things that happen when you call TADOConnection.Create(Application);?

So what you're trying to do isn't going to work. And even if it did, you should not do it. Here's some better explanations:

http://msdn.microsoft.com/en-us/library/ms682583%28VS.85%29.aspx
http://msdn.microsoft.com/en-us/library/windows/desktop/dn633971(v=vs.85).aspx
http://blogs.msdn.com/b/oldnewthing/archive/2004/01/27/63401.aspx
http://blogs.msdn.com/b/oldnewthing/archive/2004/01/28/63880.aspx
http://blogs.msdn.com/b/oldnewthing/archive/2014/08/21/10551659.aspx

MSDN suggests creating the database connection in GetExtensionVersion. This is how your isapi dll is initialized. It is not just for reporting the extension version. So that is the way to go. Create your own GetExtensionVersion function that initializes your database and then call the previous Delphi function.

library Project1;

uses
  Winapi.ActiveX,
  System.Win.ComObj,
  Web.WebBroker,
  Web.Win.ISAPIApp,
  Web.Win.ISAPIThreadPool,
  Winapi.Isapi2,
  Winapi.Windows,
  WebModuleUnit1 in 'WebModuleUnit1.pas' {WebModule1: TWebModule};

{$R *.res}

function GetExtensionVersion(var Ver: THSE_VERSION_INFO): BOOL; stdcall;
begin
  Result := Web.Win.ISAPIApp.GetExtensionVersion(Ver);
  // create your ado connection here
end;


exports
  GetExtensionVersion,
  HttpExtensionProc,
  TerminateExtension;

begin
  CoInitFlags := COINIT_MULTITHREADED;
  Application.Initialize;
  Application.WebModuleClass := WebModuleClass;
  Application.Run;
end.

Answer 2

I think the problem is that the code you run runs in the dll's main procedure. This part of the initialization is very restrictive e.g. you may not load any dll nor you are allowed to call CoInitialize (see http://msdn.microsoft.com/en-us/library/ms678543%28v=vs.85%29.aspx) . Your ActiveX alls there will cause some troubles which are most likely the reason for your exception.