how to transfer an object over a socket

In my project, I have to be able to transfer an object between clients and servers. I have tried to write some codes. Unluckily, there is always an exception "out of memory while expanding memory stream". I dont know why. Hope someone can help me. thanks. By the way, I use Indy to build connections.

unit Data;
interface
uses
Classes;
Type
TData = class(TComponent)
private
FStr : String;
public
constructor Create(AnOwner : TComponent); override;
destructor Destroy; override;
published
property Str : String read FStr write FStr;
end;
implementation
constructor TData.Create(AnOwner : TComponent);
begin
inherited Create(AnOwner);
FStr := 'It is created!!!';
end;
destructor TData.Destroy;
begin
inherited Destroy;
end;
end.
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implementation
{$R *.dfm}
uses
Data;
procedure TForm1.Button1Click(Sender: TObject);
begin
IdTCPServer1.Active := true;
end;
procedure TForm1.IdTCPServer1Connect(AThread: TIdPeerThread);
begin
Button1.Caption := 'a client';
end;
procedure TForm1.IdTCPServer1Execute(AThread: TIdPeerThread);
var
FData : TData;
FStream : TMemoryStream;
begin
FData := TData.Create(nil);
FStream := TMemoryStream.Create;
AThread.Connection.ReadStream(FStream);
FStream.ReadComponent(FData); // Here the exception comes up!!!
Edit1.Text := FData.Str;
FStream.Free;
FData.Free;
end;
end.

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implementation
uses Data;
{$R *.dfm}
procedure TForm1.Button1Click(Sender: TObject);
begin
IdTCPClient1.Connect();
Button1.Caption := 'OK';
end;
procedure TForm1.Button2Click(Sender: TObject);
var
FData : TData;
FStream : TMemoryStream;
begin
FData := TData.Create(nil);
FStream := TMemoryStream.Create;
FStream.WriteComponent(FData);
IdTCPClient1.WriteStream(FStream);
FStream.Free;
FData.Free;
end;
end.


Author: Mohammad Qermezkon
Product: Delphi 2.x (or higher)