real-time streaming (Server-Sent Events)

[jarroddavis68]

Is it possible to do?

[jarroddavis68]

I'ved tried everything I cand find. It only seems to send once and then not again. This example works without crashing.

procedure Test03();
begin
  THorse.KeepConnectionAlive := True;
  THorse.Get('/sse',
  procedure (Req: THorseRequest; Res: THorseResponse; Next: TProc)
  var
    LBuffer: TStringStream;
    I: Integer;
    s: string;
  begin
    // Set headers for SSE
    Res.RawWebResponse.ContentType := 'text/event-stream';
    Res.RawWebResponse.CustomHeaders.Values['Cache-Control'] := 'no-cache';
    Res.RawWebResponse.CustomHeaders.Values['Connection'] := 'keep-alive';

    LBuffer := TStringStream.Create('', TEncoding.UTF8);

    for I := 1 to 10 do
    begin
      Res.RawWebResponse.ContentStream := LBuffer;
      Res.RawWebResponse.FreeContentStream := False;

      s := Format('id: %d' + sLineBreak + 'event: message' + sLineBreak + 'data: Event %d at %s' + sLineBreak + sLineBreak,  [I, I, FormatDateTime('hh:nn:ss', Now)]);
      LBuffer.WriteString(s);
      writeln(LBuffer.DataString);
      Res.RawWebResponse.ContentLength := LBuffer.Size;
      Res.RawWebResponse.SendResponse;
      LBuffer.Clear;
      Sleep(1000);
    end;

    LBuffer.Free();

  end
  );

  THorse.Listen(9000,
    procedure
    begin
      WriteLn;
      Write('Press ENTER to stop server...');
      Readln;
      THorse.StopListen;
    end);
end;

[jarroddavis68]

so, I think I may have something.

• Expose TIdHTTPWebBrokerBridge of the provider, in my case, Horse.Provider.Console

  • Add this property: class property HTTPWebBrokerBridge: TIdHTTPWebBrokerBridge read FIdHTTPWebBrokerBridge;

• Get the TidContext: LCtx := THorse.HTTPWebBrokerBridge.Contexts.Pull;

  • Now you have access to the low-level connection IO handler

procedure Test03();
var
  LCtx: TidContext;
begin
  THorse.Get('/sse',
  procedure (Req: THorseRequest; Res: THorseResponse; Next: TProc)
  var
    I: Integer;
    s: string;
  begin
    LCtx := THorse.HTTPWebBrokerBridge.Contexts.Pull;

    LCtx.Connection.IOHandler.WriteLn('HTTP/1.1 200 OK');
    LCtx.Connection.IOHandler.WriteLn('Content-Type: text/event-stream; charset=UTF-8');
    LCtx.Connection.IOHandler.WriteLn('Cache-Control: no-store');
    LCtx.Connection.IOHandler.WriteLn('Connection: keep-alive');
    LCtx.Connection.IOHandler.WriteLn('Access-Control-Allow-Origin: *');
    LCtx.Connection.IOHandler.WriteLn('');


    for I := 1 to 10 do
    begin
      s := Format('id: %d' + sLineBreak + 'event: message' + sLineBreak + 'data: Event %d at %s' + sLineBreak + sLineBreak,  [I, I, FormatDateTime('hh:nn:ss', Now)]);
      writeln(s);
      LCtx.Connection.IOHandler.Write(s + #13#10#13#10);
      LCtx.Connection.IOHandler.WriteBufferFlush;
      Sleep(10);
    end;

    LCtx.Connection.IOHandler.WriteBufferFlush;
    LCtx.Connection.Disconnect;

  end
  );

  THorse.Listen(9000,
    procedure
    begin
      WriteLn;
      Write('Press ENTER to stop server...');
      Readln;
      THorse.StopListen;
    end);
end;

Seems to work. Hoping devs could chime in and validate this is not going to cause problems elsewhere.