XML: MSXML not installed

Question

Using this code to get an rss site. This code is great for my computer and many other computers. But on some computers (Windows XP or 7) I get this error: MSXML is not installed

How can I fix this problem? What's wrong?

Here is the code:

procedure My_Thread.Execute;
var
  http                 : tidhttp;
  strm                 : tmemorystream;
  str,sTitle,  sDec ,er : string;
  StartItemNode        : IXMLNode;
  ANode                : IXMLNode;
  XMLDoc               : IXMLDocument;

begin
  http := tidhttp.Create();
  strm := tmemorystream.Create;
    try
      http.Get('http://www.sample.com/rss.xml',strm);     //Download the RSS file
      SetString(str,PANSIChar(strm.Memory),strm.Size);

      XMLDoc :=  LoadXMLData(str);

      StartItemNode := XMLDoc.DocumentElement.ChildNodes.First.ChildNodes.FindNode('item');
      ANode         := StartItemNode;

      i := 0;
      repeat
        inc(i);
        sTitle    := ANode.ChildNodes['title'].Text;
        sDec       := ANode.ChildNodes['description'].Text;
        Synchronize(procedure begin            //Synchronize? I'm using threads
          case I of
            1: begin
                 main_frm.edit1.text := sTitle; //main_frm is my form
                 main_frm.edit2.text := sDec;
               end;
            2: begin
                 main_frm.edit3.text := sTitle;
                 main_frm.edit4.text := sDec;
               end;
            3: begin
                 main_frm.edit5.text := sTitle;
                 main_frm.edit6.text := sDec;
               end;
          end;
          ANode := ANode.NextSibling;
        end);
      until ANode = nil;

      http.Free;
      strm.Free;

    except
      on E: Exception do
        begin
          er := e.Message;
          Synchronize(procedure begin
            ShowMessage(er);
          end);
        end;
    end;
end;

As you can see, I use streams. Therefore, it Synchronizewas necessary.

Answer 1

MSXML COM-, CoInitialize/Ex() XML, COM COM- MSXML, IXMLDocument ( COM- , MSXML ). , , , COM- MSXML .

CoInitialize/Ex() , COM-, :

procedure My_Thread.Execute;
var
  ...
begin
  CoInitialize(nil);
  try
    ...
    XMLDoc := LoadXMLData(str);
    try
     ...
    finally
      // Since CoInitialize() and CoUninitialize() are being called in the same
      // method as local COM interface variables, it is very important to release
      // the COM interfaces before calling CoUninitialize(), do not just let them
      // release automatically when they go out of scope, as that will be too late...
      StartItemNode := nil;
      ANode := nil;
      XMLDoc := nil;
    end;
    ...
  finally
    CoUninitialize;
  end;
end;

Answer 2

MSXMLS .. servicePack2 XP MSXML 4.0 2 ( Microsoft XML) Microsoft Core XML Services (MSXML) 6.0 Windows 7.. Bye

Answer 3

I had the same problem in one of my Delphi projects, but I used the IdThreadComponent instead of the Thread object. my problem was on the line: DOC: = NewXMLDocument; I remove this line from the thread start method and wrap it right in front of the calling thread, as shown below: Doc: = NewXMLDocument; IdThreadComponent1.Start;