AsyncCallback

public ref class CallBuff {
    public: static ManualResetEventSlim^ Event = gcnew ManualResetEventSlim( false );
    public: static HttpWebRequest^ result;
};
 
 
private: System::Void button1_Click(System::Object^  sender, System::EventArgs^  e) {
    
    List<ManualResetEventSlim^>^ EventAll = gcnew List<ManualResetEventSlim^>( false );
 
    ManualResetEventSlim^ evt = gcnew ManualResetEventSlim( false );
    EventAll->Add(evt);
    HttpWebRequest^ aaa = dynamic_cast<HttpWebRequest^>(WebRequest::Create( "http://www.google.com" ));
    aaa->KeepAlive = false;
    CallBuff ^callbuffs = gcnew CallBuff;
    callbuffs->Event = evt;
    callbuffs->result = aaa;
    aaa->BeginGetResponse(gcnew AsyncCallback(this, &grabber_graf::Form1::ResponseCallback), callbuffs);
 
    
    evt = gcnew ManualResetEventSlim( false );
    EventAll->Add(evt);
    aaa = dynamic_cast<HttpWebRequest^>(WebRequest::Create( "http://microsoft.com" ));
    aaa->KeepAlive = false;
    callbuffs = gcnew CallBuff;
    callbuffs->Event = evt;
    callbuffs->result = aaa;
    aaa->BeginGetResponse(gcnew AsyncCallback(this, &grabber_graf::Form1::ResponseCallback), callbuffs);
    
 
    for each(ManualResetEventSlim^ evt in EventAll) {
        evt->Wait();
    }
}
 
//Калбек
private: void ResponseCallback(IAsyncResult^ result) {
 
    CallBuff ^callbuffs = dynamic_cast<CallBuff^>(result->AsyncState);
 
    HttpWebRequest^ Request = dynamic_cast<HttpWebRequest^>(callbuffs->result);
    HttpWebResponse^ resp = dynamic_cast<HttpWebResponse^>(Request->EndGetResponse(result));
    MessageBox::Show("Код исполняется!", "Анализ страниц");
    resp->Close();
    callbuffs->Event->Set();
}