Delphi ISAPI: How to access Accept-Language in an Apache host?

Question

I wrote a web service using content-negotiation with ISAPI using Delphi XE4.

My code contains

ARequest.GetFieldByName('Accept-Language')

which outputs the correct value if I use a standalone server (Indy Bridge), but it is empty if I use an ISAPI DLL inside Apache.

Is there any way I can access this header field with ISAPI in Apache?

Answer 1

Since ISAPI is kind-of a successor to CGI, the 'default' HTTP headers get converted to CGI-style parameters, so you need to request HTTP_ACCEPT_LANGUAGE using the extension control block's GetServerVariable. Like so:

function GetVar(pecb: PEXTENSION_CONTROL_BLOCK; const key:AnsiString):AnsiString;
var
  l:cardinal;
begin
  l:=$10000;
  SetLength(Result,l);
  if not(pecb.GetServerVariable(pecb.ConnID,PAnsiChar(key),PAnsiChar(Result),l)) then
    if GetLastError=ERROR_INVALID_INDEX then l:=1 else RaiseLastOSError;
  SetLength(Result,l-1);
end; 

//
GetVar(ecb,'HTTP_ACCEPT_LANGUAGE')