Sockets

I socket sono una tecnologia di trasferimento dati di basso livello su cui vengono implementati molti protocolli di rete. Windows offre classi socket TCP e UDP per applicazioni client-server o peer-to-peer, indipendentemente dal fatto che le connessioni siano di lunga durata o che non sia necessaria una connessione stabilita.

Questo argomento illustra come usare le classi socket di Windows che si trovano nello spazio dei nomi Windows.Networking.Sockets. Ma è anche possibile usare Windows Sockets 2 (Winsock) in un'app Windows.

Note

di conseguenza dell'isolamento della rete, Windows non consente di stabilire una connessione socket (Socket o WinSock) tra due app Windows in esecuzione nello stesso computer, indipendentemente dal fatto che sia tramite l'indirizzo di loopback locale (127.0.0.1) o specificando in modo esplicito l'indirizzo IP locale. Per informazioni dettagliate sui meccanismi in base ai quali le app Windows possono comunicare tra loro, vedi Comunicazione tra app.

Creare un client e un server socket TCP di base

Un socket TCP (Transmission Control Protocol) fornisce trasferimenti di dati di rete di basso livello in entrambe le direzioni per le connessioni di lunga durata. I socket TCP sono la funzionalità sottostante usata dalla maggior parte dei protocolli di rete usati su Internet. Per illustrare le operazioni TCP di base, il codice di esempio seguente mostra un oggetto StreamSocket e un oggetto StreamSocketListener che invia e riceve dati tramite TCP per formare un client echo e un server.

Per iniziare con il minor numero possibile di componenti e, per il momento, evitare i problemi di isolamento di rete, crea un nuovo progetto e inserisci nello stesso progetto sia il codice client sia quello server riportati di seguito.

Sarà necessario dichiarare una funzionalità dell'app nel progetto. Aprire il file di origine del manifesto del pacchetto dell'app (il Package.appxmanifest file) e nella scheda Funzionalità selezionare Reti private (Client & Server). Ecco come appare nel codice di markup Package.appxmanifest.

<Capability Name="privateNetworkClientServer" />

Invece di privateNetworkClientServer, è possibile dichiarare internetClientServer se ci si connette tramite Internet. Sia StreamSocket che StreamSocketListener devono essere dichiarate una o altre di queste funzionalità dell'app.

Un client echo e un server che usano socket TCP

Creare un oggetto StreamSocketListener e iniziare ad ascoltare le connessioni TCP in ingresso. L'evento StreamSocketListener.ConnectionReceived viene generato ogni volta che un client stabilisce una connessione con StreamSocketListener.

Creare anche un StreamSocket, stabilire una connessione al server, inviare una richiesta e ricevere una risposta.

Creare una nuova pagina denominata StreamSocketAndListenerPage. Inserire il markup XAML in StreamSocketAndListenerPage.xamle inserire il codice imperativo all'interno della StreamSocketAndListenerPage classe .

<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height="*"/>
    </Grid.RowDefinitions>

    <StackPanel>
        <TextBlock Margin="9.6,0" Style="{StaticResource TitleTextBlockStyle}" Text="TCP socket example"/>
        <TextBlock Margin="7.2,0,0,0" Style="{StaticResource HeaderTextBlockStyle}" Text="StreamSocket &amp; StreamSocketListener"/>
    </StackPanel>

    <Grid Grid.Row="1">
        <Grid.RowDefinitions>
            <RowDefinition/>
            <RowDefinition/>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"/>
            <ColumnDefinition Width="*"/>
        </Grid.ColumnDefinitions>
        <TextBlock Margin="9.6" Style="{StaticResource SubtitleTextBlockStyle}" Text="client"/>
        <ListBox x:Name="clientListBox" Grid.Row="1" Margin="9.6"/>
        <TextBlock Grid.Column="1" Margin="9.6" Style="{StaticResource SubtitleTextBlockStyle}" Text="server"/>
        <ListBox x:Name="serverListBox" Grid.Column="1" Grid.Row="1" Margin="9.6"/>
    </Grid>
</Grid>

// Every protocol typically has a standard port number. For example, HTTP is typically 80, FTP is 20 and 21, etc.
// For this example, we'll choose an arbitrary port number.
static string PortNumber = "1337";

protected override void OnNavigatedTo(NavigationEventArgs e)
{
    this.StartServer();
    this.StartClient();
}

private async void StartServer()
{
    try
    {
        var streamSocketListener = new Windows.Networking.Sockets.StreamSocketListener();

        // The ConnectionReceived event is raised when connections are received.
        streamSocketListener.ConnectionReceived += this.StreamSocketListener_ConnectionReceived;

        // Start listening for incoming TCP connections on the specified port. You can specify any port that's not currently in use.
        await streamSocketListener.BindServiceNameAsync(StreamSocketAndListenerPage.PortNumber);

        this.serverListBox.Items.Add("server is listening...");
    }
    catch (Exception ex)
    {
        Windows.Networking.Sockets.SocketErrorStatus webErrorStatus = Windows.Networking.Sockets.SocketError.GetStatus(ex.GetBaseException().HResult);
        this.serverListBox.Items.Add(webErrorStatus.ToString() != "Unknown" ? webErrorStatus.ToString() : ex.Message);
    }
}

private async void StreamSocketListener_ConnectionReceived(Windows.Networking.Sockets.StreamSocketListener sender, Windows.Networking.Sockets.StreamSocketListenerConnectionReceivedEventArgs args)
{
    string request;
    using (var streamReader = new StreamReader(args.Socket.InputStream.AsStreamForRead()))
    {
        request = await streamReader.ReadLineAsync();
    }

    DispatcherQueue.TryEnqueue(() => this.serverListBox.Items.Add(string.Format("server received the request: \"{0}\"", request)));

    // Echo the request back as the response.
    using (Stream outputStream = args.Socket.OutputStream.AsStreamForWrite())
    {
        using (var streamWriter = new StreamWriter(outputStream))
        {
            await streamWriter.WriteLineAsync(request);
            await streamWriter.FlushAsync();
        }
    }

    DispatcherQueue.TryEnqueue(() => this.serverListBox.Items.Add(string.Format("server sent back the response: \"{0}\"", request)));

    sender.Dispose();

    DispatcherQueue.TryEnqueue(() => this.serverListBox.Items.Add("server closed its socket"));
}

private async void StartClient()
{
    try
    {
        // Create the StreamSocket and establish a connection to the echo server.
        using (var streamSocket = new Windows.Networking.Sockets.StreamSocket())
        {
            // The server hostname that we will be establishing a connection to. In this example, the server and client are in the same process.
            var hostName = new Windows.Networking.HostName("localhost");

            this.clientListBox.Items.Add("client is trying to connect...");

            await streamSocket.ConnectAsync(hostName, StreamSocketAndListenerPage.PortNumber);

            this.clientListBox.Items.Add("client connected");

            // Send a request to the echo server.
            string request = "Hello, World!";
            using (Stream outputStream = streamSocket.OutputStream.AsStreamForWrite())
            {
                using (var streamWriter = new StreamWriter(outputStream))
                {
                    await streamWriter.WriteLineAsync(request);
                    await streamWriter.FlushAsync();
                }
            }

            this.clientListBox.Items.Add(string.Format("client sent the request: \"{0}\"", request));

            // Read data from the echo server.
            string response;
            using (Stream inputStream = streamSocket.InputStream.AsStreamForRead())
            {
                using (StreamReader streamReader = new StreamReader(inputStream))
                {
                    response = await streamReader.ReadLineAsync();
                }
            }

            this.clientListBox.Items.Add(string.Format("client received the response: \"{0}\" ", response));
        }

        this.clientListBox.Items.Add("client closed its socket");
    }
    catch (Exception ex)
    {
        Windows.Networking.Sockets.SocketErrorStatus webErrorStatus = Windows.Networking.Sockets.SocketError.GetStatus(ex.GetBaseException().HResult);
        this.clientListBox.Items.Add(webErrorStatus.ToString() != "Unknown" ? webErrorStatus.ToString() : ex.Message);
    }
}

#include <winrt/Windows.Foundation.h>
#include <winrt/Windows.Networking.Sockets.h>
#include <winrt/Windows.Storage.Streams.h>
#include <winrt/Microsoft.UI.Dispatching.h>
#include <winrt/Microsoft.UI.Xaml.Navigation.h>
#include <sstream>

using namespace winrt;
using namespace Windows::Foundation;
using namespace Windows::Storage::Streams;
using namespace Microsoft::UI::Dispatching;
using namespace Microsoft::UI::Xaml::Navigation;
...
private:
    Windows::Networking::Sockets::StreamSocketListener m_streamSocketListener;
    Windows::Networking::Sockets::StreamSocket m_streamSocket;

public:
    void OnNavigatedTo(NavigationEventArgs const& /* e */)
    {
        StartServer();
        StartClient();
    }

private:
    IAsyncAction StartServer()
    {
        try
        {
            // The ConnectionReceived event is raised when connections are received.
            m_streamSocketListener.ConnectionReceived({ this, &StreamSocketAndListenerPage::OnConnectionReceived });

            // Start listening for incoming TCP connections on the specified port. You can specify any port that's not currently in use.
            // Every protocol typically has a standard port number. For example, HTTP is typically 80, FTP is 20 and 21, etc.
            // For this example, we'll choose an arbitrary port number.
            co_await m_streamSocketListener.BindServiceNameAsync(L"1337");
            serverListBox().Items().Append(winrt::box_value(L"server is listening..."));
        }
        catch (winrt::hresult_error const& ex)
        {
            Windows::Networking::Sockets::SocketErrorStatus webErrorStatus{ Windows::Networking::Sockets::SocketError::GetStatus(ex.to_abi()) };
            serverListBox().Items().Append(webErrorStatus != Windows::Networking::Sockets::SocketErrorStatus::Unknown ? winrt::box_value(winrt::to_hstring((int32_t)webErrorStatus)) : winrt::box_value(winrt::to_hstring(ex.to_abi())));
        }
    }

    IAsyncAction OnConnectionReceived(Windows::Networking::Sockets::StreamSocketListener /* sender */, Windows::Networking::Sockets::StreamSocketListenerConnectionReceivedEventArgs args)
    {
        try
        {
            auto socket{ args.Socket() }; // Keep the socket referenced, and alive.
            DataReader dataReader{ socket.InputStream() };

            unsigned int bytesLoaded = co_await dataReader.LoadAsync(sizeof(unsigned int));

            unsigned int stringLength = dataReader.ReadUInt32();
            bytesLoaded = co_await dataReader.LoadAsync(stringLength);
            winrt::hstring request = dataReader.ReadString(bytesLoaded);

            serverListBox().DispatcherQueue().TryEnqueue([=]()
            {
                std::wstringstream wstringstream;
                wstringstream << L"server received the request: \"" << request.c_str() << L"\"";
                serverListBox().Items().Append(winrt::box_value(wstringstream.str().c_str()));
            });

            // Echo the request back as the response.
            DataWriter dataWriter{ socket.OutputStream() };
            dataWriter.WriteUInt32(request.size());
            dataWriter.WriteString(request);
            co_await dataWriter.StoreAsync();
            dataWriter.DetachStream();

            serverListBox().DispatcherQueue().TryEnqueue([=]()
            {
                std::wstringstream wstringstream;
                wstringstream << L"server sent back the response: \"" << request.c_str() << L"\"";
                serverListBox().Items().Append(winrt::box_value(wstringstream.str().c_str()));
            });

            m_streamSocketListener = nullptr;

            serverListBox().DispatcherQueue().TryEnqueue([=]()
            {
                serverListBox().Items().Append(winrt::box_value(L"server closed its socket"));
            });
        }
        catch (winrt::hresult_error const& ex)
        {
            Windows::Networking::Sockets::SocketErrorStatus webErrorStatus{ Windows::Networking::Sockets::SocketError::GetStatus(ex.to_abi()) };
            serverListBox().DispatcherQueue().TryEnqueue([=]()
            {
                serverListBox().Items().Append(webErrorStatus != Windows::Networking::Sockets::SocketErrorStatus::Unknown ? winrt::box_value(winrt::to_hstring((int32_t)webErrorStatus)) : winrt::box_value(winrt::to_hstring(ex.to_abi())));
            });
        }
    }

    IAsyncAction StartClient()
    {
        try
        {
            // Establish a connection to the echo server.

            // The server hostname that we will be establishing a connection to. In this example, the server and client are in the same process.
            Windows::Networking::HostName hostName{ L"localhost" };

            clientListBox().Items().Append(winrt::box_value(L"client is trying to connect..."));

            co_await m_streamSocket.ConnectAsync(hostName, L"1337");
            clientListBox().Items().Append(winrt::box_value(L"client connected"));

            // Send a request to the echo server.
            DataWriter dataWriter{ m_streamSocket.OutputStream() };
            winrt::hstring request{ L"Hello, World!" };
            dataWriter.WriteUInt32(request.size());
            dataWriter.WriteString(request);

            co_await dataWriter.StoreAsync();

            std::wstringstream wstringstream;
            wstringstream << L"client sent the request: \"" << request.c_str() << L"\"";
            clientListBox().Items().Append(winrt::box_value(wstringstream.str().c_str()));

            co_await dataWriter.FlushAsync();
            dataWriter.DetachStream();

            // Read data from the echo server.
            DataReader dataReader{ m_streamSocket.InputStream() };
            unsigned int bytesLoaded = co_await dataReader.LoadAsync(sizeof(unsigned int));
            unsigned int stringLength = dataReader.ReadUInt32();
            bytesLoaded = co_await dataReader.LoadAsync(stringLength);
            winrt::hstring response{ dataReader.ReadString(bytesLoaded) };

            wstringstream.str(L"");
            wstringstream << L"client received the response: \"" << response.c_str() << L"\"";
            clientListBox().Items().Append(winrt::box_value(wstringstream.str().c_str()));

            m_streamSocket = nullptr;

            clientListBox().Items().Append(winrt::box_value(L"client closed its socket"));
        }
        catch (winrt::hresult_error const& ex)
        {
            Windows::Networking::Sockets::SocketErrorStatus webErrorStatus{ Windows::Networking::Sockets::SocketError::GetStatus(ex.to_abi()) };
            serverListBox().Items().Append(webErrorStatus != Windows::Networking::Sockets::SocketErrorStatus::Unknown ? winrt::box_value(winrt::to_hstring((int32_t)webErrorStatus)) : winrt::box_value(winrt::to_hstring(ex.to_abi())));
        }
    }

#include <ppltasks.h>
#include <sstream>
...
using namespace Windows::Foundation;
using namespace Windows::Storage::Streams;
using namespace Windows::UI::Core;
using namespace Windows::UI::Xaml::Navigation;
...
private:
    Windows::Networking::Sockets::StreamSocketListener^ streamSocketListener;
    Windows::Networking::Sockets::StreamSocket^ streamSocket;

protected:
    virtual void OnNavigatedTo(NavigationEventArgs^ e) override
    {
        this->StartServer();
        this->StartClient();
    }

private:
    void StartServer()
    {
        try
        {
            this->streamSocketListener = ref new Windows::Networking::Sockets::StreamSocketListener();

            // The ConnectionReceived event is raised when connections are received.
            streamSocketListener->ConnectionReceived += ref new TypedEventHandler<Windows::Networking::Sockets::StreamSocketListener^, Windows::Networking::Sockets::StreamSocketListenerConnectionReceivedEventArgs^>(this, &StreamSocketAndListenerPage::StreamSocketListener_ConnectionReceived);

            // Start listening for incoming TCP connections on the specified port. You can specify any port that's not currently in use.
            // Every protocol typically has a standard port number. For example, HTTP is typically 80, FTP is 20 and 21, etc.
            // For this example, we'll choose an arbitrary port number.
            Concurrency::create_task(streamSocketListener->BindServiceNameAsync(L"1337")).then(
                [=]
            {
                this->serverListBox->Items->Append(L"server is listening...");
            });
        }
        catch (Platform::Exception^ ex)
        {
            Windows::Networking::Sockets::SocketErrorStatus webErrorStatus = Windows::Networking::Sockets::SocketError::GetStatus(ex->HResult);
            this->serverListBox->Items->Append(webErrorStatus.ToString() != L"Unknown" ? webErrorStatus.ToString() : ex->Message);
        }
    }

    void StreamSocketListener_ConnectionReceived(Windows::Networking::Sockets::StreamSocketListener^ sender, Windows::Networking::Sockets::StreamSocketListenerConnectionReceivedEventArgs^ args)
    {
        try
        {
            auto dataReader = ref new DataReader(args->Socket->InputStream);

            Concurrency::create_task(dataReader->LoadAsync(sizeof(unsigned int))).then(
                [=](unsigned int bytesLoaded)
            {
                unsigned int stringLength = dataReader->ReadUInt32();
                Concurrency::create_task(dataReader->LoadAsync(stringLength)).then(
                    [=](unsigned int bytesLoaded)
                {
                    Platform::String^ request = dataReader->ReadString(bytesLoaded);
                    this->Dispatcher->RunAsync(CoreDispatcherPriority::Normal, ref new DispatchedHandler(
                        [=]
                    {
                        std::wstringstream wstringstream;
                        wstringstream << L"server received the request: \"" << request->Data() << L"\"";
                        this->serverListBox->Items->Append(ref new Platform::String(wstringstream.str().c_str()));
                    }));

                    // Echo the request back as the response.
                    auto dataWriter = ref new DataWriter(args->Socket->OutputStream);
                    dataWriter->WriteUInt32(request->Length());
                    dataWriter->WriteString(request);
                    Concurrency::create_task(dataWriter->StoreAsync()).then(
                        [=](unsigned int)
                    {
                        dataWriter->DetachStream();

                        this->Dispatcher->RunAsync(CoreDispatcherPriority::Normal, ref new DispatchedHandler(
                            [=]()
                        {
                            std::wstringstream wstringstream;
                            wstringstream << L"server sent back the response: \"" << request->Data() << L"\"";
                            this->serverListBox->Items->Append(ref new Platform::String(wstringstream.str().c_str()));
                        }));

                        delete this->streamSocketListener;
                        this->streamSocketListener = nullptr;

                        this->Dispatcher->RunAsync(CoreDispatcherPriority::Normal, ref new DispatchedHandler([=]() {this->serverListBox->Items->Append(L"server closed its socket"); }));
                    });
                });
            });
        }
        catch (Platform::Exception^ ex)
        {
            Windows::Networking::Sockets::SocketErrorStatus webErrorStatus = Windows::Networking::Sockets::SocketError::GetStatus(ex->HResult);
            this->Dispatcher->RunAsync(CoreDispatcherPriority::Normal, ref new DispatchedHandler([=]() {this->serverListBox->Items->Append(webErrorStatus.ToString() != L"Unknown" ? webErrorStatus.ToString() : ex->Message); }));
        }
    }

    void StartClient()
    {
        try
        {
            // Create the StreamSocket and establish a connection to the echo server.
            this->streamSocket = ref new Windows::Networking::Sockets::StreamSocket();

            // The server hostname that we will be establishing a connection to. In this example, the server and client are in the same process.
            auto hostName = ref new Windows::Networking::HostName(L"localhost");

            this->clientListBox->Items->Append(L"client is trying to connect...");

            Concurrency::create_task(this->streamSocket->ConnectAsync(hostName, L"1337")).then(
                [=](Concurrency::task< void >)
            {
                this->clientListBox->Items->Append(L"client connected");

                // Send a request to the echo server.
                auto dataWriter = ref new DataWriter(this->streamSocket->OutputStream);
                auto request = ref new Platform::String(L"Hello, World!");
                dataWriter->WriteUInt32(request->Length());
                dataWriter->WriteString(request);

                Concurrency::create_task(dataWriter->StoreAsync()).then(
                    [=](Concurrency::task< unsigned int >)
                {
                    std::wstringstream wstringstream;
                    wstringstream << L"client sent the request: \"" << request->Data() << L"\"";
                    this->clientListBox->Items->Append(ref new Platform::String(wstringstream.str().c_str()));

                    Concurrency::create_task(dataWriter->FlushAsync()).then(
                        [=](Concurrency::task< bool >)
                    {
                        dataWriter->DetachStream();

                        // Read data from the echo server.
                        auto dataReader = ref new DataReader(this->streamSocket->InputStream);
                        Concurrency::create_task(dataReader->LoadAsync(sizeof(unsigned int))).then(
                            [=](unsigned int bytesLoaded)
                        {
                            unsigned int stringLength = dataReader->ReadUInt32();
                            Concurrency::create_task(dataReader->LoadAsync(stringLength)).then(
                                [=](unsigned int bytesLoaded)
                            {
                                Platform::String^ response = dataReader->ReadString(bytesLoaded);
                                this->Dispatcher->RunAsync(CoreDispatcherPriority::Normal, ref new DispatchedHandler(
                                    [=]
                                {
                                    std::wstringstream wstringstream;
                                    wstringstream << L"client received the response: \"" << response->Data() << L"\"";
                                    this->clientListBox->Items->Append(ref new Platform::String(wstringstream.str().c_str()));

                                    delete this->streamSocket;
                                    this->streamSocket = nullptr;

                                    this->clientListBox->Items->Append(L"client closed its socket");
                                }));
                            });
                        });
                    });
                });
            });
        }
        catch (Platform::Exception^ ex)
        {
            Windows::Networking::Sockets::SocketErrorStatus webErrorStatus = Windows::Networking::Sockets::SocketError::GetStatus(ex->HResult);
            this->serverListBox->Items->Append(webErrorStatus.ToString() != L"Unknown" ? webErrorStatus.ToString() : ex->Message);
        }
    }

Riferimenti a StreamSocket nelle continuazioni PPL C++ (si applica principalmente a C++/CX)

Note

Se si usano coroutine C++/WinRT e si passano parametri per valore, questo problema non si applica. Per indicazioni sul passaggio di parametri, vedere Concorrenza e operazioni asincrone con C++/WinRT.

Un oggetto StreamSocket rimane attivo finché è presente un flusso di lettura/scrittura attivo nel flusso di input/output, ad esempio streamSocketListenerConnectionReceivedEventArgs.Socket a cui si ha accesso nel gestore eventi StreamSocketListener.ConnectionReceived . Quando chiami DataReader.LoadAsync (o ReadAsync/WriteAsync/StoreAsync), viene mantenuto un riferimento al socket (tramite il flusso di input del socket) finché il gestore dell'evento Completed (se presente) di LoadAsync non ha terminato l'esecuzione.

La libreria Parallel Patterns Library (PPL) non pianifica per impostazione predefinita le continuazioni di attività in linea. In altre parole, l'aggiunta di un'attività di continuazione (con task::then()) non garantisce che l'attività di continuazione venga eseguita in linea nel gestore di completamento.

void StreamSocketListener_ConnectionReceived(Windows::Networking::Sockets::StreamSocketListener^ sender, Windows::Networking::Sockets::StreamSocketListenerConnectionReceivedEventArgs^ args)
{
    auto dataReader = ref new DataReader(args->Socket->InputStream);
    Concurrency::create_task(dataReader->LoadAsync(sizeof(unsigned int))).then(
        [=](unsigned int bytesLoaded)
    {
        // Work in here isn't guaranteed to execute inline as the completion handler of the LoadAsync.
    });
}

Dal punto di vista della StreamSocket, il gestore di completamento ha terminato l'esecuzione (e il socket può essere rilasciato) prima che venga eseguito il corpo della continuazione. Pertanto, per evitare che il socket venga distrutto se vuoi usarlo all'interno di quella continuazione, devi fare riferimento al socket direttamente (tramite la cattura nella lambda) e usarlo, oppure indirettamente (continuando ad accedere a args->Socket all'interno delle continuazioni), oppure forzare l'esecuzione inline delle attività di continuazione. È possibile visualizzare la prima tecnica (acquisizione lambda) in azione nell'esempio StreamSocket. Il codice C++/CX nella sezione Creare un client e un server socket TCP di base qui sopra usa la seconda tecnica: rimanda la richiesta come risposta e accede a args->Socket dall'interno di una delle continuazioni più interne.

La terza tecnica è appropriata quando non si ripete una risposta. Si usa l'opzione task_continuation_context::use_synchronous_execution() per forzare PPL a eseguire il corpo di continuazione in linea. Ecco un esempio di codice che illustra come eseguire questa operazione.

void StreamSocketListener_ConnectionReceived(Windows::Networking::Sockets::StreamSocketListener^ sender, Windows::Networking::Sockets::StreamSocketListenerConnectionReceivedEventArgs^ args)
{
    auto dataReader = ref new DataReader(args->Socket->InputStream);

    Concurrency::create_task(dataReader->LoadAsync(sizeof(unsigned int))).then(
        [=](unsigned int bytesLoaded)
    {
        unsigned int messageLength = dataReader->ReadUInt32();
        Concurrency::create_task(dataReader->LoadAsync(messageLength)).then(
            [=](unsigned int bytesLoaded)
        {
            Platform::String^ request = dataReader->ReadString(bytesLoaded);
            this->Dispatcher->RunAsync(CoreDispatcherPriority::Normal, ref new DispatchedHandler(
                [=]
            {
                std::wstringstream wstringstream;
                wstringstream << L"server received the request: \"" << request->Data() << L"\"";
                this->serverListBox->Items->Append(ref new Platform::String(wstringstream.str().c_str()));
            }));
        });
    }, Concurrency::task_continuation_context::use_synchronous_execution());
}

Questo comportamento si applica a tutte le classi Socket e WebSocket nello spazio dei nomi Windows.Networking.Sockets. Tuttavia, gli scenari lato client in genere archiviano i socket nelle variabili membro, quindi il problema è più applicabile allo scenario StreamSocketListener.ConnectionReceived , come illustrato in precedenza.

Creare un client e un server socket UDP di base

Un socket UDP (User Datagram Protocol) è simile a un socket TCP in quanto fornisce anche trasferimenti di dati di rete di basso livello in entrambe le direzioni. Tuttavia, mentre un socket TCP è destinato a connessioni di lunga durata, un socket UDP è destinato alle applicazioni in cui non è necessaria una connessione stabilita. Poiché i socket UDP non mantengono la connessione in entrambi gli endpoint, sono una soluzione semplice e veloce per la rete tra computer remoti. Ma i socket UDP non garantiscono né l'integrità dei pacchetti di rete né che i pacchetti arrivino affatto alla destinazione remota. L'app dovrà quindi essere progettata per tollerarlo. Alcuni esempi di applicazioni che usano socket UDP sono l'individuazione della rete locale e i client di chat locali.

Per illustrare le operazioni UDP di base, il codice di esempio seguente mostra la classe DatagramSocket usata per inviare e ricevere dati tramite UDP per formare un client echo e un server. Creare un nuovo progetto e inserire sia il client che il codice del server seguente nello stesso progetto. Proprio come per un socket TCP, è necessario dichiarare la funzionalità dell'app Reti private (Client & Server).

Un client echo e un server che usano socket UDP

Creare un DatagramSocket per svolgere il ruolo di server di eco, associarlo a un numero di porta specifico, restare in ascolto di un messaggio UDP in arrivo e rinviarlo al mittente. L'evento DatagramSocket.MessageReceived viene generato quando viene ricevuto un messaggio nel socket.

Costruire un altro DatagramSocket per svolgere il ruolo del client echo, associarlo a un numero di porta specifico, inviare un messaggio UDP e ricevere una risposta.

Creare una nuova pagina denominata DatagramSocketPage. Inserire il markup XAML in DatagramSocketPage.xamle inserire il codice imperativo all'interno della DatagramSocketPage classe .

<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height="*"/>
    </Grid.RowDefinitions>

    <StackPanel>
        <TextBlock Margin="9.6,0" Style="{StaticResource TitleTextBlockStyle}" Text="UDP socket example"/>
        <TextBlock Margin="7.2,0,0,0" Style="{StaticResource HeaderTextBlockStyle}" Text="DatagramSocket"/>
    </StackPanel>

    <Grid Grid.Row="1">
        <Grid.RowDefinitions>
            <RowDefinition/>
            <RowDefinition/>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"/>
            <ColumnDefinition Width="*"/>
        </Grid.ColumnDefinitions>
        <TextBlock Margin="9.6" Style="{StaticResource SubtitleTextBlockStyle}" Text="client"/>
        <ListBox x:Name="clientListBox" Grid.Row="1" Margin="9.6"/>
        <TextBlock Grid.Column="1" Margin="9.6" Style="{StaticResource SubtitleTextBlockStyle}" Text="server"/>
        <ListBox x:Name="serverListBox" Grid.Column="1" Grid.Row="1" Margin="9.6"/>
    </Grid>
</Grid>

// Every protocol typically has a standard port number. For example, HTTP is typically 80, FTP is 20 and 21, etc.
// For this example, we'll choose different arbitrary port numbers for client and server, since both will be running on the same machine.
static string ClientPortNumber = "1336";
static string ServerPortNumber = "1337";

protected override void OnNavigatedTo(NavigationEventArgs e)
{
    this.StartServer();
    this.StartClient();
}

private async void StartServer()
{
    try
    {
        var serverDatagramSocket = new Windows.Networking.Sockets.DatagramSocket();

        // The ConnectionReceived event is raised when connections are received.
        serverDatagramSocket.MessageReceived += ServerDatagramSocket_MessageReceived;

        this.serverListBox.Items.Add("server is about to bind...");

        // Start listening for incoming UDP datagrams on the specified port. You can specify any port that's not currently in use.
        await serverDatagramSocket.BindServiceNameAsync(DatagramSocketPage.ServerPortNumber);

        this.serverListBox.Items.Add(string.Format("server is bound to port number {0}", DatagramSocketPage.ServerPortNumber));
    }
    catch (Exception ex)
    {
        Windows.Networking.Sockets.SocketErrorStatus webErrorStatus = Windows.Networking.Sockets.SocketError.GetStatus(ex.GetBaseException().HResult);
        this.serverListBox.Items.Add(webErrorStatus.ToString() != "Unknown" ? webErrorStatus.ToString() : ex.Message);
    }
}

private async void ServerDatagramSocket_MessageReceived(Windows.Networking.Sockets.DatagramSocket sender, Windows.Networking.Sockets.DatagramSocketMessageReceivedEventArgs args)
{
    string request;
    using (DataReader dataReader = args.GetDataReader())
    {
        request = dataReader.ReadString(dataReader.UnconsumedBufferLength).Trim();
    }

    DispatcherQueue.TryEnqueue(() => this.serverListBox.Items.Add(string.Format("server received the request: \"{0}\"", request)));

    // Echo the request back as the response.
    using (Stream outputStream = (await sender.GetOutputStreamAsync(args.RemoteAddress, DatagramSocketPage.ClientPortNumber)).AsStreamForWrite())
    {
        using (var streamWriter = new StreamWriter(outputStream))
        {
            await streamWriter.WriteLineAsync(request);
            await streamWriter.FlushAsync();
        }
    }

    DispatcherQueue.TryEnqueue(() => this.serverListBox.Items.Add(string.Format("server sent back the response: \"{0}\"", request)));

    sender.Dispose();

    DispatcherQueue.TryEnqueue(() => this.serverListBox.Items.Add("server closed its socket"));
}

private async void StartClient()
{
    try
    {
        // Create the DatagramSocket and establish a connection to the echo server.
        var clientDatagramSocket = new Windows.Networking.Sockets.DatagramSocket();

        clientDatagramSocket.MessageReceived += ClientDatagramSocket_MessageReceived;

        // The server hostname that we will be establishing a connection to. In this example, the server and client are in the same process.
        var hostName = new Windows.Networking.HostName("localhost");

        this.clientListBox.Items.Add("client is about to bind...");

        await clientDatagramSocket.BindServiceNameAsync(DatagramSocketPage.ClientPortNumber);

        this.clientListBox.Items.Add(string.Format("client is bound to port number {0}", DatagramSocketPage.ClientPortNumber));

        // Send a request to the echo server.
        string request = "Hello, World!";
        using (var serverDatagramSocket = new Windows.Networking.Sockets.DatagramSocket())
        {
            using (Stream outputStream = (await serverDatagramSocket.GetOutputStreamAsync(hostName, DatagramSocketPage.ServerPortNumber)).AsStreamForWrite())
            {
                using (var streamWriter = new StreamWriter(outputStream))
                {
                    await streamWriter.WriteLineAsync(request);
                    await streamWriter.FlushAsync();
                }
            }
        }

        this.clientListBox.Items.Add(string.Format("client sent the request: \"{0}\"", request));
    }
    catch (Exception ex)
    {
        Windows.Networking.Sockets.SocketErrorStatus webErrorStatus = Windows.Networking.Sockets.SocketError.GetStatus(ex.GetBaseException().HResult);
        this.clientListBox.Items.Add(webErrorStatus.ToString() != "Unknown" ? webErrorStatus.ToString() : ex.Message);
    }
}

private async void ClientDatagramSocket_MessageReceived(Windows.Networking.Sockets.DatagramSocket sender, Windows.Networking.Sockets.DatagramSocketMessageReceivedEventArgs args)
{
    string response;
    using (DataReader dataReader = args.GetDataReader())
    {
        response = dataReader.ReadString(dataReader.UnconsumedBufferLength).Trim();
    }

    DispatcherQueue.TryEnqueue(() => this.clientListBox.Items.Add(string.Format("client received the response: \"{0}\"", response)));

    sender.Dispose();

    DispatcherQueue.TryEnqueue(() => this.clientListBox.Items.Add("client closed its socket"));
}

#include <winrt/Windows.Foundation.h>
#include <winrt/Windows.Networking.Sockets.h>
#include <winrt/Windows.Storage.Streams.h>
#include <winrt/Microsoft.UI.Dispatching.h>
#include <winrt/Microsoft.UI.Xaml.Navigation.h>
#include <sstream>

using namespace winrt;
using namespace Windows::Foundation;
using namespace Windows::Storage::Streams;
using namespace Microsoft::UI::Dispatching;
using namespace Microsoft::UI::Xaml::Navigation;
...
private:
    Windows::Networking::Sockets::DatagramSocket m_clientDatagramSocket;
    Windows::Networking::Sockets::DatagramSocket m_serverDatagramSocket;

public:
    void OnNavigatedTo(NavigationEventArgs const& /* e */)
    {
        StartServer();
        StartClient();
    }

private:
    IAsyncAction StartServer()
    {
        try
        {
            // The ConnectionReceived event is raised when connections are received.
            m_serverDatagramSocket.MessageReceived({ this, &DatagramSocketPage::ServerDatagramSocket_MessageReceived });

            serverListBox().Items().Append(winrt::box_value(L"server is about to bind..."));

            // Start listening for incoming UDP datagrams on the specified port. You can specify any port that's not currently in use.
            co_await m_serverDatagramSocket.BindServiceNameAsync(L"1337");
            serverListBox().Items().Append(winrt::box_value(L"server is bound to port number 1337"));
        }
        catch (winrt::hresult_error const& ex)
        {
            Windows::Networking::Sockets::SocketErrorStatus webErrorStatus{ Windows::Networking::Sockets::SocketError::GetStatus(ex.to_abi()) };
            serverListBox().Items().Append(webErrorStatus != Windows::Networking::Sockets::SocketErrorStatus::Unknown ? winrt::box_value(winrt::to_hstring((int32_t)webErrorStatus)) : winrt::box_value(winrt::to_hstring(ex.to_abi())));
        }
    }

    IAsyncAction ServerDatagramSocket_MessageReceived(Windows::Networking::Sockets::DatagramSocket sender, Windows::Networking::Sockets::DatagramSocketMessageReceivedEventArgs args)
    {
        DataReader dataReader{ args.GetDataReader() };
        winrt::hstring request{ dataReader.ReadString(dataReader.UnconsumedBufferLength()) };

        serverListBox().DispatcherQueue().TryEnqueue([=]()
        {
            std::wstringstream wstringstream;
            wstringstream << L"server received the request: \"" << request.c_str() << L"\"";
            serverListBox().Items().Append(winrt::box_value(wstringstream.str().c_str()));
        });

        // Echo the request back as the response.
        IOutputStream outputStream = co_await sender.GetOutputStreamAsync(args.RemoteAddress(), L"1336");
        DataWriter dataWriter{ outputStream };
        dataWriter.WriteString(request);

        co_await dataWriter.StoreAsync();
        dataWriter.DetachStream();

        serverListBox().DispatcherQueue().TryEnqueue([=]()
        {
            std::wstringstream wstringstream;
            wstringstream << L"server sent back the response: \"" << request.c_str() << L"\"";
            serverListBox().Items().Append(winrt::box_value(wstringstream.str().c_str()));

            m_serverDatagramSocket = nullptr;

            serverListBox().Items().Append(winrt::box_value(L"server closed its socket"));
        });
    }

    IAsyncAction StartClient()
    {
        try
        {
            m_clientDatagramSocket.MessageReceived({ this, &DatagramSocketPage::ClientDatagramSocket_MessageReceived });

            // Establish a connection to the echo server.
            // The server hostname that we will be establishing a connection to. In this example, the server and client are in the same process.
            Windows::Networking::HostName hostName{ L"localhost" };

            clientListBox().Items().Append(winrt::box_value(L"client is about to bind..."));

            co_await m_clientDatagramSocket.BindServiceNameAsync(L"1336");
            clientListBox().Items().Append(winrt::box_value(L"client is bound to port number 1336"));

            // Send a request to the echo server.
            IOutputStream outputStream = co_await m_clientDatagramSocket.GetOutputStreamAsync(hostName, L"1337");

            winrt::hstring request{ L"Hello, World!" };
            DataWriter dataWriter{ outputStream };
            dataWriter.WriteString(request);
            co_await dataWriter.StoreAsync();
            dataWriter.DetachStream();

            std::wstringstream wstringstream;
            wstringstream << L"client sent the request: \"" << request.c_str() << L"\"";
            clientListBox().Items().Append(winrt::box_value(wstringstream.str().c_str()));
        }
        catch (winrt::hresult_error const& ex)
        {
            Windows::Networking::Sockets::SocketErrorStatus webErrorStatus{ Windows::Networking::Sockets::SocketError::GetStatus(ex.to_abi()) };
            serverListBox().Items().Append(webErrorStatus != Windows::Networking::Sockets::SocketErrorStatus::Unknown ? winrt::box_value(winrt::to_hstring((int32_t)webErrorStatus)) : winrt::box_value(winrt::to_hstring(ex.to_abi())));
        }
    }

    void ClientDatagramSocket_MessageReceived(Windows::Networking::Sockets::DatagramSocket const& /* sender */, Windows::Networking::Sockets::DatagramSocketMessageReceivedEventArgs const& args)
    {
        DataReader dataReader{ args.GetDataReader() };
        winrt::hstring response{ dataReader.ReadString(dataReader.UnconsumedBufferLength()) };
        clientListBox().DispatcherQueue().TryEnqueue([=]()
        {
            std::wstringstream wstringstream;
            wstringstream << L"client received the response: \"" << response.c_str() << L"\"";
            clientListBox().Items().Append(winrt::box_value(wstringstream.str().c_str()));
        });

        m_clientDatagramSocket = nullptr;

        clientListBox().DispatcherQueue().TryEnqueue([=]()
        {
            clientListBox().Items().Append(winrt::box_value(L"client closed its socket"));
        });
    }

#include <ppltasks.h>
#include <sstream>
...
using namespace Windows::Foundation;
using namespace Windows::Storage::Streams;
using namespace Windows::UI::Core;
using namespace Windows::UI::Xaml::Navigation;
...
private:
    Windows::Networking::Sockets::DatagramSocket^ clientDatagramSocket;
    Windows::Networking::Sockets::DatagramSocket^ serverDatagramSocket;

protected:
    virtual void OnNavigatedTo(NavigationEventArgs^ e) override
    {
        this->StartServer();
        this->StartClient();
    }

private:
    void StartServer()
    {
        try
        {
            this->serverDatagramSocket = ref new Windows::Networking::Sockets::DatagramSocket();

            // The ConnectionReceived event is raised when connections are received.
            this->serverDatagramSocket->MessageReceived += ref new TypedEventHandler<Windows::Networking::Sockets::DatagramSocket^, Windows::Networking::Sockets::DatagramSocketMessageReceivedEventArgs^>(this, &DatagramSocketPage::ServerDatagramSocket_MessageReceived);

            this->serverListBox->Items->Append(L"server is about to bind...");

            // Start listening for incoming UDP datagrams on the specified port. You can specify any port that's not currently in use.
            Concurrency::create_task(this->serverDatagramSocket->BindServiceNameAsync("1337")).then(
                [=]
            {
                this->serverListBox->Items->Append(L"server is bound to port number 1337");
            });
        }
        catch (Platform::Exception^ ex)
        {
            Windows::Networking::Sockets::SocketErrorStatus webErrorStatus = Windows::Networking::Sockets::SocketError::GetStatus(ex->HResult);
            this->serverListBox->Items->Append(webErrorStatus.ToString() != L"Unknown" ? webErrorStatus.ToString() : ex->Message);
        }
    }

    void ServerDatagramSocket_MessageReceived(Windows::Networking::Sockets::DatagramSocket^ sender, Windows::Networking::Sockets::DatagramSocketMessageReceivedEventArgs^ args)
    {
        DataReader^ dataReader = args->GetDataReader();
        Platform::String^ request = dataReader->ReadString(dataReader->UnconsumedBufferLength);
        this->Dispatcher->RunAsync(CoreDispatcherPriority::Normal, ref new DispatchedHandler(
            [=]
        {
            std::wstringstream wstringstream;
            wstringstream << L"server received the request: \"" << request->Data() << L"\"";
            this->serverListBox->Items->Append(ref new Platform::String(wstringstream.str().c_str()));
        }));

        // Echo the request back as the response.
        Concurrency::create_task(sender->GetOutputStreamAsync(args->RemoteAddress, "1336")).then(
            [=](IOutputStream^ outputStream)
        {
            auto dataWriter = ref new DataWriter(outputStream);
            dataWriter->WriteString(request);
            Concurrency::create_task(dataWriter->StoreAsync()).then(
                [=](unsigned int)
            {
                dataWriter->DetachStream();

                this->Dispatcher->RunAsync(CoreDispatcherPriority::Normal, ref new DispatchedHandler(
                    [=]()
                {
                    std::wstringstream wstringstream;
                    wstringstream << L"server sent back the response: \"" << request->Data() << L"\"";
                    this->serverListBox->Items->Append(ref new Platform::String(wstringstream.str().c_str()));

                    delete this->serverDatagramSocket;
                    this->serverDatagramSocket = nullptr;

                    this->Dispatcher->RunAsync(CoreDispatcherPriority::Normal, ref new DispatchedHandler([=]() {this->serverListBox->Items->Append(L"server closed its socket"); }));
                }));
            });
        });
    }

    void StartClient()
    {
        try
        {
            // Create the DatagramSocket and establish a connection to the echo server.
            this->clientDatagramSocket = ref new Windows::Networking::Sockets::DatagramSocket();

            this->clientDatagramSocket->MessageReceived += ref new TypedEventHandler<Windows::Networking::Sockets::DatagramSocket^, Windows::Networking::Sockets::DatagramSocketMessageReceivedEventArgs^>(this, &DatagramSocketPage::ClientDatagramSocket_MessageReceived);

            // The server hostname that we will be establishing a connection to. In this example, the server and client are in the same process.
            auto hostName = ref new Windows::Networking::HostName(L"localhost");

            this->clientListBox->Items->Append(L"client is about to bind...");

            Concurrency::create_task(this->clientDatagramSocket->BindServiceNameAsync("1336")).then(
                [=]
            {
                this->clientListBox->Items->Append(L"client is bound to port number 1336");
            });

            // Send a request to the echo server.
            auto serverDatagramSocket = ref new Windows::Networking::Sockets::DatagramSocket();
            Concurrency::create_task(serverDatagramSocket->GetOutputStreamAsync(hostName, "1337")).then(
                [=](IOutputStream^ outputStream)
            {
                auto request = ref new Platform::String(L"Hello, World!");
                auto dataWriter = ref new DataWriter(outputStream);
                dataWriter->WriteString(request);
                Concurrency::create_task(dataWriter->StoreAsync()).then(
                    [=](unsigned int)
                {
                    dataWriter->DetachStream();
                    std::wstringstream wstringstream;
                    wstringstream << L"client sent the request: \"" << request->Data() << L"\"";
                    this->clientListBox->Items->Append(ref new Platform::String(wstringstream.str().c_str()));
                });

            });
        }
        catch (Platform::Exception^ ex)
        {
            Windows::Networking::Sockets::SocketErrorStatus webErrorStatus = Windows::Networking::Sockets::SocketError::GetStatus(ex->HResult);
            this->serverListBox->Items->Append(webErrorStatus.ToString() != L"Unknown" ? webErrorStatus.ToString() : ex->Message);
        }
    }

    void ClientDatagramSocket_MessageReceived(Windows::Networking::Sockets::DatagramSocket^ sender, Windows::Networking::Sockets::DatagramSocketMessageReceivedEventArgs^ args)
    {
        DataReader^ dataReader = args->GetDataReader();
        Platform::String^ response = dataReader->ReadString(dataReader->UnconsumedBufferLength);
        this->Dispatcher->RunAsync(CoreDispatcherPriority::Normal, ref new DispatchedHandler(
            [=]
        {
            std::wstringstream wstringstream;
            wstringstream << L"client received the response: \"" << response->Data() << L"\"";
            this->clientListBox->Items->Append(ref new Platform::String(wstringstream.str().c_str()));
        }));

        delete this->clientDatagramSocket;
        this->clientDatagramSocket = nullptr;

        this->Dispatcher->RunAsync(CoreDispatcherPriority::Normal, ref new DispatchedHandler([=]() {this->clientListBox->Items->Append(L"client closed its socket"); }));
    }

Operazioni in background e broker di socket

È possibile usare il gestore del socket e i trigger del canale di controllo per assicurarsi che l'app riceva correttamente le connessioni o i dati sui socket mentre non è in primo piano. Per altre info, vedi Comunicazioni di rete in background.

Invio in batch

Ogni volta che si scrive nel flusso associato a un socket, viene eseguita una transizione dalla modalità utente (il codice) alla modalità kernel (dove lo stack di rete è). Se si scrivono molti buffer alla volta, queste transizioni ripetute si complicano in un sovraccarico notevole. L'invio in batch degli invii è un modo per inviare più buffer di dati insieme ed evitare questo sovraccarico. È particolarmente utile se l'app esegue VoIP, VPN o altre attività che comportano lo spostamento di molti dati nel modo più efficiente possibile.

Questa sezione illustra un paio di tecniche di invio in batch che è possibile usare con un oggetto StreamSocket o un DatagramSocket connesso.

Per ottenere una baseline, vediamo come inviare un numero elevato di buffer in modo inefficiente. Ecco una demo minima che usa streamSocket.

protected override async void OnNavigatedTo(NavigationEventArgs e)
{
    var streamSocketListener = new Windows.Networking.Sockets.StreamSocketListener();
    streamSocketListener.ConnectionReceived += this.StreamSocketListener_ConnectionReceived;
    await streamSocketListener.BindServiceNameAsync("1337");

    var streamSocket = new Windows.Networking.Sockets.StreamSocket();
    await streamSocket.ConnectAsync(new Windows.Networking.HostName("localhost"), "1337");
    this.SendMultipleBuffersInefficiently(streamSocket, "Hello, World!");
    //this.BatchedSendsCSharpOnly(streamSocket, "Hello, World!");
    //this.BatchedSendsAnyUWPLanguage(streamSocket, "Hello, World!");
}

private async void StreamSocketListener_ConnectionReceived(Windows.Networking.Sockets.StreamSocketListener sender, Windows.Networking.Sockets.StreamSocketListenerConnectionReceivedEventArgs args)
{
    using (var dataReader = new DataReader(args.Socket.InputStream))
    {
        dataReader.InputStreamOptions = InputStreamOptions.Partial;
        while (true)
        {
            await dataReader.LoadAsync(256);
            if (dataReader.UnconsumedBufferLength == 0) break;
            IBuffer requestBuffer = dataReader.ReadBuffer(dataReader.UnconsumedBufferLength);
            string request = Windows.Security.Cryptography.CryptographicBuffer.ConvertBinaryToString(Windows.Security.Cryptography.BinaryStringEncoding.Utf8, requestBuffer);
            Debug.WriteLine(string.Format("server received the request: \"{0}\"", request));
        }
    }
}

// This implementation incurs kernel transition overhead for each packet written.
private async void SendMultipleBuffersInefficiently(Windows.Networking.Sockets.StreamSocket streamSocket, string message)
{
    var packetsToSend = new List<IBuffer>();
    for (int count = 0; count < 5; ++count) { packetsToSend.Add(Windows.Security.Cryptography.CryptographicBuffer.ConvertStringToBinary(message, Windows.Security.Cryptography.BinaryStringEncoding.Utf8)); }

    foreach (IBuffer packet in packetsToSend)
    {
        await streamSocket.OutputStream.WriteAsync(packet);
    }
}

#include <winrt/Windows.Foundation.h>
#include <winrt/Windows.Networking.Sockets.h>
#include <winrt/Windows.Security.Cryptography.h>
#include <winrt/Windows.Storage.Streams.h>
#include <winrt/Microsoft.UI.Dispatching.h>
#include <winrt/Microsoft.UI.Xaml.Navigation.h>
#include <sstream>

using namespace winrt;
using namespace Windows::Foundation;
using namespace Windows::Storage::Streams;
using namespace Microsoft::UI::Dispatching;
using namespace Microsoft::UI::Xaml::Navigation;
...
private:
    Windows::Networking::Sockets::StreamSocketListener m_streamSocketListener;
    Windows::Networking::Sockets::StreamSocket m_streamSocket;

public:
    IAsyncAction OnNavigatedTo(NavigationEventArgs /* e */)
    {
        m_streamSocketListener.ConnectionReceived({ this, &BatchedSendsPage::OnConnectionReceived });
        co_await m_streamSocketListener.BindServiceNameAsync(L"1337");

        co_await m_streamSocket.ConnectAsync(Windows::Networking::HostName{ L"localhost" }, L"1337");
        SendMultipleBuffersInefficientlyAsync(L"Hello, World!");
        //BatchedSendsAnyUWPLanguageAsync(L"Hello, World!");
    }

private:
    IAsyncAction OnConnectionReceived(Windows::Networking::Sockets::StreamSocketListener const& /* sender */, Windows::Networking::Sockets::StreamSocketListenerConnectionReceivedEventArgs const& args)
    {
        DataReader dataReader{ args.Socket().InputStream() };
        dataReader.InputStreamOptions(Windows::Storage::Streams::InputStreamOptions::Partial);

        while (true)
        {
            unsigned int bytesLoaded = co_await dataReader.LoadAsync(256);
            if (bytesLoaded == 0) break;
            winrt::hstring message{ dataReader.ReadString(bytesLoaded) };
            ::OutputDebugString(message.c_str());
        }
    }

    // This implementation incurs kernel transition overhead for each packet written.
    IAsyncAction SendMultipleBuffersInefficientlyAsync(winrt::hstring message)
    {
        co_await winrt::resume_background();

        std::vector< IBuffer > packetsToSend;
        for (unsigned int count = 0; count < 5; ++count)
        {
            packetsToSend.push_back(Windows::Security::Cryptography::CryptographicBuffer::ConvertStringToBinary(message, Windows::Security::Cryptography::BinaryStringEncoding::Utf8));
        }

        for (auto const& element : packetsToSend)
        {
            m_streamSocket.OutputStream().WriteAsync(element).get();
        }
    }

#include <ppltasks.h>
#include <sstream>
...
using namespace Windows::Foundation;
using namespace Windows::Storage::Streams;
using namespace Windows::UI::Core;
using namespace Windows::UI::Xaml::Navigation;
...
private:
    Windows::Networking::Sockets::StreamSocketListener^ streamSocketListener;
    Windows::Networking::Sockets::StreamSocket^ streamSocket;

protected:
    virtual void OnNavigatedTo(NavigationEventArgs^ e) override
    {
        this->streamSocketListener = ref new Windows::Networking::Sockets::StreamSocketListener();
        streamSocketListener->ConnectionReceived += ref new TypedEventHandler<Windows::Networking::Sockets::StreamSocketListener^, Windows::Networking::Sockets::StreamSocketListenerConnectionReceivedEventArgs^>(this, &BatchedSendsPage::StreamSocketListener_ConnectionReceived);
        Concurrency::create_task(this->streamSocketListener->BindServiceNameAsync(L"1337")).then(
            [=]
        {
            this->streamSocket = ref new Windows::Networking::Sockets::StreamSocket();
            Concurrency::create_task(this->streamSocket->ConnectAsync(ref new Windows::Networking::HostName(L"localhost"), L"1337")).then(
                [=](Concurrency::task< void >)
            {
                this->SendMultipleBuffersInefficiently(L"Hello, World!");
                // this->BatchedSendsAnyUWPLanguage(L"Hello, World!");
            }, Concurrency::task_continuation_context::use_synchronous_execution());
        });
    }

private:
    void StreamSocketListener_ConnectionReceived(Windows::Networking::Sockets::StreamSocketListener^ sender, Windows::Networking::Sockets::StreamSocketListenerConnectionReceivedEventArgs^ args)
    {
        auto dataReader = ref new DataReader(args->Socket->InputStream);
        dataReader->InputStreamOptions = Windows::Storage::Streams::InputStreamOptions::Partial;
        this->ReceiveStringRecurse(dataReader, args->Socket);
    }

    void ReceiveStringRecurse(DataReader^ dataReader, Windows::Networking::Sockets::StreamSocket^ streamSocket)
    {
        Concurrency::create_task(dataReader->LoadAsync(256)).then(
            [this, dataReader, streamSocket](unsigned int bytesLoaded)
        {
            if (bytesLoaded == 0) return;
            Platform::String^ message = dataReader->ReadString(bytesLoaded);
            ::OutputDebugString(message->Data());
            this->ReceiveStringRecurse(dataReader, streamSocket);
        });
    }

    // This implementation incurs kernel transition overhead for each packet written.
    void SendMultipleBuffersInefficiently(Platform::String^ message)
    {
        std::vector< IBuffer^ > packetsToSend{};
        for (unsigned int count = 0; count < 5; ++count)
        {
            packetsToSend.push_back(Windows::Security::Cryptography::CryptographicBuffer::ConvertStringToBinary(message, Windows::Security::Cryptography::BinaryStringEncoding::Utf8));
        }

        for (auto element : packetsToSend)
        {
            Concurrency::create_task(this->streamSocket->OutputStream->WriteAsync(element)).wait();
        }
    }

Questo primo esempio di tecnica più efficiente è appropriato solo se si usa C#. Modificare OnNavigatedTo per chiamare BatchedSendsCSharpOnly anziché SendMultipleBuffersInefficiently o SendMultipleBuffersInefficientlyAsync.

// A C#-only technique for batched sends.
private async void BatchedSendsCSharpOnly(Windows.Networking.Sockets.StreamSocket streamSocket, string message)
{
    var packetsToSend = new List<IBuffer>();
    for (int count = 0; count < 5; ++count) { packetsToSend.Add(Windows.Security.Cryptography.CryptographicBuffer.ConvertStringToBinary(message, Windows.Security.Cryptography.BinaryStringEncoding.Utf8)); }

    var pendingTasks = new System.Threading.Tasks.Task[packetsToSend.Count];

    for (int index = 0; index < packetsToSend.Count; ++index)
    {
        // track all pending writes as tasks, but don't wait on one before beginning the next.
        pendingTasks[index] = streamSocket.OutputStream.WriteAsync(packetsToSend[index]).AsTask();
        // Don't modify any buffer's contents until the pending writes are complete.
    }

    // Wait for all of the pending writes to complete.
    System.Threading.Tasks.Task.WaitAll(pendingTasks);
}

Questo esempio successivo è appropriato per qualsiasi linguaggio UWP, non solo per C#. Si basa sul comportamento di StreamSocket.OutputStream e DatagramSocket.OutputStream che accorpa gli invii. La tecnica richiama FlushAsync su tale flusso di output che, a partire da Windows 10, garantisce la restituzione solo dopo il completamento di tutte le operazioni sul flusso di output.

// An implementation of batched sends suitable for any UWP language.
private async void BatchedSendsAnyUWPLanguage(Windows.Networking.Sockets.StreamSocket streamSocket, string message)
{
    var packetsToSend = new List<IBuffer>();
    for (int count = 0; count < 5; ++count) { packetsToSend.Add(Windows.Security.Cryptography.CryptographicBuffer.ConvertStringToBinary(message, Windows.Security.Cryptography.BinaryStringEncoding.Utf8)); }

    var pendingWrites = new IAsyncOperationWithProgress<uint, uint>[packetsToSend.Count];

    for (int index = 0; index < packetsToSend.Count; ++index)
    {
        // track all pending writes as tasks, but don't wait on one before beginning the next.
        pendingWrites[index] = streamSocket.OutputStream.WriteAsync(packetsToSend[index]);
        // Don't modify any buffer's contents until the pending writes are complete.
    }

    // Wait for all of the pending writes to complete. This step enables batched sends on the output stream.
    await streamSocket.OutputStream.FlushAsync();
}

// An implementation of batched sends suitable for any UWP language.
IAsyncAction BatchedSendsAnyUWPLanguageAsync(winrt::hstring message)
{
    std::vector< IBuffer > packetsToSend{};
    std::vector< IAsyncOperationWithProgress< unsigned int, unsigned int > > pendingWrites{};
    for (unsigned int count = 0; count < 5; ++count)
    {
        packetsToSend.push_back(Windows::Security::Cryptography::CryptographicBuffer::ConvertStringToBinary(message, Windows::Security::Cryptography::BinaryStringEncoding::Utf8));
    }

    for (auto const& element : packetsToSend)
    {
        // track all pending writes as tasks, but don't wait on one before beginning the next.
        pendingWrites.push_back(m_streamSocket.OutputStream().WriteAsync(element));
        // Don't modify any buffer's contents until the pending writes are complete.
    }

    // Wait for all of the pending writes to complete. This step enables batched sends on the output stream.
    co_await m_streamSocket.OutputStream().FlushAsync();
}

private:
    // An implementation of batched sends suitable for any UWP language.
    void BatchedSendsAnyUWPLanguage(Platform::String^ message)
    {
        std::vector< IBuffer^ > packetsToSend{};
        std::vector< IAsyncOperationWithProgress< unsigned int, unsigned int >^ >pendingWrites{};
        for (unsigned int count = 0; count < 5; ++count)
        {
            packetsToSend.push_back(Windows::Security::Cryptography::CryptographicBuffer::ConvertStringToBinary(message, Windows::Security::Cryptography::BinaryStringEncoding::Utf8));
        }

        for (auto element : packetsToSend)
        {
            // track all pending writes as tasks, but don't wait on one before beginning the next.
            pendingWrites.push_back(this->streamSocket->OutputStream->WriteAsync(element));
            // Don't modify any buffer's contents until the pending writes are complete.
        }

        // Wait for all of the pending writes to complete. This step enables batched sends on the output stream.
        Concurrency::create_task(this->streamSocket->OutputStream->FlushAsync());
    }

Esistono alcune limitazioni importanti imposte usando gli invii in batch nel codice.

  • Non è possibile modificare il contenuto delle istanze IBuffer scritte fino al completamento della scrittura asincrona.
  • Il modello FlushAsync funziona solo su StreamSocket.OutputStream e DatagramSocket.OutputStream.
  • Il modello FlushAsync funziona solo in Windows 10 e versioni successive.
  • In altri casi, usare Task.WaitAll anziché il modello FlushAsync .

Condivisione delle porte per DatagramSocket

Puoi configurare un DatagramSocket in modo che coesista con altri socket multicast Win32 o UWP collegati allo stesso indirizzo/porta. A tale scopo, impostare DatagramSocketControl.MulticastOnly su true prima dell'associazione o della connessione del socket. È possibile accedere a un'istanza di DatagramSocketControl dall'oggetto DatagramSocket stesso tramite la relativa proprietà DatagramSocket.Control .

Fornire un certificato client con la classe StreamSocket

StreamSocket supporta l'uso di SSL/TLS per autenticare il server a cui comunica l'app client. In alcuni casi, l'app client deve eseguire l'autenticazione al server usando un certificato client SSL/TLS. È possibile fornire un certificato client con la proprietà StreamSocketControl.ClientCertificate prima dell'associazione o della connessione del socket (deve essere impostata prima dell'avvio dell'handshake SSL/TLS). È possibile accedere a un'istanza di StreamSocketControl dall'oggetto StreamSocket stesso tramite la relativa proprietà StreamSocket.Control . Se il server richiede il certificato client, Windows risponderà con il certificato client fornito.

Usare un override di StreamSocket.ConnectAsync che accetta socketProtectionLevel, come illustrato in questo esempio di codice minimo.

Important

Come indicato dal commento negli esempi di codice seguenti, il progetto deve dichiarare la funzionalità dell'app sharedUserCertificates per il funzionamento di questo codice.

// For this code to work, you need at least one certificate to be present in the user MY certificate store.
// Plugging a smartcard into a smartcard reader connected to your PC will achieve that.
// Also, your project needs to declare the sharedUserCertificates app capability.
var certificateQuery = new Windows.Security.Cryptography.Certificates.CertificateQuery();
certificateQuery.StoreName = "MY";
IReadOnlyList<Windows.Security.Cryptography.Certificates.Certificate> certificates = await Windows.Security.Cryptography.Certificates.CertificateStores.FindAllAsync(certificateQuery);
if (certificates.Count > 0)
{
    streamSocket.Control.ClientCertificate = certificates[0];
    await streamSocket.ConnectAsync(hostName, "1337", Windows.Networking.Sockets.SocketProtectionLevel.Tls12);
}

// For this code to work, you need at least one certificate to be present in the user MY certificate store.
// Plugging a smartcard into a smartcard reader connected to your PC will achieve that.
// Also, your project needs to declare the sharedUserCertificates app capability.
Windows::Security::Cryptography::Certificates::CertificateQuery certificateQuery;
certificateQuery.StoreName(L"MY");
IVectorView< Windows::Security::Cryptography::Certificates::Certificate > certificates = co_await Windows::Security::Cryptography::Certificates::CertificateStores::FindAllAsync(certificateQuery);

if (certificates.Size() > 0)
{
    m_streamSocket.Control().ClientCertificate(certificates.GetAt(0));
    co_await m_streamSocket.ConnectAsync(Windows::Networking::HostName{ L"localhost" }, L"1337", Windows::Networking::Sockets::SocketProtectionLevel::Tls12);
    ...
}

// For this code to work, you need at least one certificate to be present in the user MY certificate store.
// Plugging a smartcard into a smartcard reader connected to your PC will achieve that.
// Also, your project needs to declare the sharedUserCertificates app capability.
auto certificateQuery = ref new Windows::Security::Cryptography::Certificates::CertificateQuery();
certificateQuery->StoreName = L"MY";
Concurrency::create_task(Windows::Security::Cryptography::Certificates::CertificateStores::FindAllAsync(certificateQuery)).then(
    [=](IVectorView< Windows::Security::Cryptography::Certificates::Certificate^ >^ certificates)
{
    if (certificates->Size > 0)
    {
        this->streamSocket->Control->ClientCertificate = certificates->GetAt(0);
        Concurrency::create_task(this->streamSocket->ConnectAsync(ref new Windows::Networking::HostName(L"localhost"), L"1337", Windows::Networking::Sockets::SocketProtectionLevel::Tls12)).then(
            [=]
        {
            ...
        });
    }
});

Gestione delle eccezioni

Un errore rilevato in un'operazione DatagramSocket, StreamSocket o StreamSocketListener viene restituito come valore HRESULT . È possibile passare tale valore HRESULT al metodo SocketError.GetStatus per convertirlo in un valore di enumerazione SocketErrorStatus .

La maggior parte dei valori di enumerazione SocketErrorStatus corrisponde a un errore restituito dall'operazione nativa Windows sockets. L'app può attivare i valori di enumerazione SocketErrorStatus per modificare il comportamento dell'app a seconda della causa dell'eccezione.

Per gli errori di convalida dei parametri, è possibile usare HRESULT dall'eccezione per ottenere informazioni più dettagliate sull'errore. I possibili valori HRESULT sono elencati in Winerror.h, che è possibile trovare nell'installazione dell'SDK , ad esempio nella cartella C:\Program Files (x86)\Windows Kits\10\Include\<VERSION>\shared. Per la maggior parte degli errori di convalida dei parametri, il valore HRESULT restituito è E_INVALIDARG.

Il costruttore HostName può generare un'eccezione se la stringa passata non è un nome host valido. Ad esempio, contiene caratteri non consentiti, che è probabile se il nome host viene digitato nell'app dall'utente. Costruire un hostName all'interno di un blocco try/catch. In questo modo, se viene generata un'eccezione, l'app può inviare una notifica all'utente e richiedere un nuovo nome host.

API importanti

Samples

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