Listen on Blocknative's mempool WebSocket API

Unit1.pas

uses
  // Delphi
  System.Classes,
  System.JSON,
  System.UITypes,
  // FireMonkey
  FMX.Controls,
  FMX.Controls.Presentation,
  FMX.Dialogs,
  FMX.Forms,
  FMX.Memo,
  FMX.Memo.Types,
  FMX.ScrollBox,
  FMX.StdCtrls,
  FMX.Types,
  // web3
  web3,
  web3.eth.blocknative.mempool,
  web3.eth.blocknative.mempool.sgc;

type
  TForm1 = class(TForm)
    Memo1: TMemo;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    Mempool: IMempool;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.fmx}

procedure TForm1.Button1Click(Sender: TObject);
begin
  Mempool := TSgcMempool.Subscribe(
    Ethereum,                                     // ethereum main net
    TProxy.Disabled,                              // no proxy server
    'xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx',       // your blocknative API key
    '0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48', // address to watch
    procedure(event: TJsonObject; err: IError)    // continuous events (or a blocknative error)
    begin
      var tx := web3.eth.blocknative.mempool.getTransaction(event);
      if Assigned(tx) then
        TThread.Synchronize(nil, procedure
        begin
          Memo1.Lines.Add(tx.ToString);
        end);
    end,
    procedure(err: IError) // non-blocknative-error handler (probably a socket error)
    begin
      TThread.Synchronize(nil, procedure
      begin
        MessageDlg(err.Message, TMsgDlgType.mtError, [TMsgDlgBtn.mbOK], 0);
      end);
    end,
    procedure
    begin
      // connection closed
    end).Value;
end;