PeerFinder.Start Method

Reference

Definition

Namespace:: Windows.Networking.Proximity

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Overloads

Start()	Makes an app discoverable to remote peers.
Start(String)	Makes an app discoverable to remote peers.

Start()

Edit

Makes an app discoverable to remote peers.

public:
 static void Start();

/// [Windows.Foundation.Metadata.Overload("Start")]
 static void Start();

[Windows.Foundation.Metadata.Overload("Start")]
public static void Start();

function start()

Public Shared Sub Start ()

Attributes: OverloadAttribute

Windows requirements

App capabilities

ID_CAP_NETWORKING [Windows Phone] ID_CAP_NETWORKING [Windows Phone] ID_CAP_PROXIMITY [Windows Phone] proximity ID_CAP_PROXIMITY [Windows Phone]

Examples

protected override void OnNavigatedTo(NavigationEventArgs e)
{
    DisplayNameTextBox.Text = Windows.Networking.Proximity.PeerFinder.DisplayName;
    Windows.Networking.Proximity.PeerFinder.ConnectionRequested += ConnectionRequested;

    // If activated from launch or from the background, create a peer connection.
    var args = e.Parameter as Windows.ApplicationModel.Activation.LaunchActivatedEventArgs;
    if (args != null && args.Kind == Windows.ApplicationModel.Activation.ActivationKind.Launch)
    {
        if (args.Arguments == "Windows.Networking.Proximity.PeerFinder:StreamSocket")
        {
            AdvertiseForPeersButton_Click(null, null);
        }
    }
}

protected override void OnNavigatingFrom(NavigatingCancelEventArgs e)
{
    if (_started)
    {
        // Detach the callback handler (there can only be one PeerConnectProgress handler).
        Windows.Networking.Proximity.PeerFinder.TriggeredConnectionStateChanged -= TriggeredConnectionStateChanged;
        // Detach the incoming connection request event handler.
        Windows.Networking.Proximity.PeerFinder.ConnectionRequested -= ConnectionRequested;
        Windows.Networking.Proximity.PeerFinder.Stop();
        CloseSocket();
        _started = false;
    }
}

// Write a message to MessageBlock on the UI thread.
private Windows.UI.Core.CoreDispatcher messageDispatcher = Window.Current.CoreWindow.Dispatcher;

async private void WriteMessageText(string message, bool overwrite = false)
{
    await messageDispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
        () =>
        {
            if (overwrite)
                MessageBlock.Text = message;
            else
                MessageBlock.Text += message;
        });
}

bool _started = false;

// Click event handler for "Advertise" button.
private void AdvertiseForPeersButton_Click(object sender, RoutedEventArgs e)
{
    if (_started) 
    {
        WriteMessageText("You are already advertising for a connection.\n");
        return; 
    }

    Windows.Networking.Proximity.PeerFinder.DisplayName = DisplayNameTextBox.Text;

    if ((Windows.Networking.Proximity.PeerFinder.SupportedDiscoveryTypes &
         Windows.Networking.Proximity.PeerDiscoveryTypes.Triggered) ==
         Windows.Networking.Proximity.PeerDiscoveryTypes.Triggered)
    {
        Windows.Networking.Proximity.PeerFinder.TriggeredConnectionStateChanged +=
            TriggeredConnectionStateChanged;

        WriteMessageText("You can tap to connect a peer device that is " +
                         "also advertising for a connection.\n");
    }
    else
    {
        WriteMessageText("Tap to connect is not supported.\n");
    }

    if ((Windows.Networking.Proximity.PeerFinder.SupportedDiscoveryTypes &
         Windows.Networking.Proximity.PeerDiscoveryTypes.Browse) !=
         Windows.Networking.Proximity.PeerDiscoveryTypes.Browse)
    {
        WriteMessageText("Peer discovery using Wi-Fi Direct is not supported.\n");
    }

   Windows.Networking.Proximity.PeerFinder.Start();
   _started = true;
}

private void TriggeredConnectionStateChanged(
    object sender,
    Windows.Networking.Proximity.TriggeredConnectionStateChangedEventArgs e)
{
    if (e.State == Windows.Networking.Proximity.TriggeredConnectState.PeerFound)
    {
        WriteMessageText("Peer found. You may now pull your devices out of proximity.\n");
    }
    if (e.State == Windows.Networking.Proximity.TriggeredConnectState.Completed)
    {
        WriteMessageText("Connected. You may now send a message.\n");
        SendMessage(e.Socket);
    }
}

// Click event handler for "Browse" button.
async private void FindPeersButton_Click(object sender, RoutedEventArgs e)
{
    if ((Windows.Networking.Proximity.PeerFinder.SupportedDiscoveryTypes &
         Windows.Networking.Proximity.PeerDiscoveryTypes.Browse) !=
         Windows.Networking.Proximity.PeerDiscoveryTypes.Browse)
    {
        WriteMessageText("Peer discovery using Wi-Fi Direct is not supported.\n");
        return;
    }

    try
    {
        var peerInfoCollection = await Windows.Networking.Proximity.PeerFinder.FindAllPeersAsync();
        if (peerInfoCollection.Count > 0)
        {
            // Connect to first peer found - example only.
            // In your app, provide the user with a list of available peers.
            ConnectToPeer(peerInfoCollection[0]);
        }
    }
    catch (Exception err)
    {
        WriteMessageText("Error finding peers: " + err.Message + "\n");
    }
}

async private void ConnectToPeer(Windows.Networking.Proximity.PeerInformation peerInfo)
{
    WriteMessageText("Peer found. Connecting to " + peerInfo.DisplayName + "\n");
    try
    {
        Windows.Networking.Sockets.StreamSocket socket =
            await Windows.Networking.Proximity.PeerFinder.ConnectAsync(peerInfo);

        WriteMessageText("Connection successful. You may now send messages.\n");
        SendMessage(socket);
    }
    catch (Exception err)
    {
        WriteMessageText("Connection failed: " + err.Message + "\n");
    }

    requestingPeer = null;
}

// Click event handler for "Stop" button.
private void StopFindingPeersButton_Click(object sender, RoutedEventArgs e)
{
    _started = false;
    Windows.Networking.Proximity.PeerFinder.Stop();
    if (proximitySocket != null) { CloseSocket(); }
}

// Handle external connection requests.
Windows.Networking.Proximity.PeerInformation requestingPeer;

private void ConnectionRequested(object sender,
    Windows.Networking.Proximity.ConnectionRequestedEventArgs e)
{
    requestingPeer = e.PeerInformation;
    WriteMessageText("Connection requested by " + requestingPeer.DisplayName + ". " +
        "Click 'Accept Connection' to connect.");
}

private void AcceptConnectionButton_Click(object sender, RoutedEventArgs e)
{
    if (requestingPeer == null)
    {
        WriteMessageText("No peer connection has been requested.");
        return;
    }

    ConnectToPeer(requestingPeer);
}

Protected Overrides Sub OnNavigatedTo(e As Navigation.NavigationEventArgs)
    DisplayNameTextBox.Text = Windows.Networking.Proximity.PeerFinder.DisplayName
    AddHandler Windows.Networking.Proximity.PeerFinder.ConnectionRequested, AddressOf ConnectionRequested

    ' If activated from launch or from the background, create a peer connection.
    Dim args = TryCast(e.Parameter, Windows.ApplicationModel.Activation.LaunchActivatedEventArgs)
    If args IsNot Nothing AndAlso args.Kind = Windows.ApplicationModel.Activation.ActivationKind.Launch Then

        If args.Arguments = "Windows.Networking.Proximity.PeerFinder:StreamSocket" Then
            AdvertiseForPeersButton_Click()
        End If
    End If
End Sub

Protected Overrides Sub OnNavigatingFrom(e As Navigation.NavigatingCancelEventArgs)
    If _started Then
        ' Detach the callback handler (there can only be one PeerConnectProgress handler).
        RemoveHandler Windows.Networking.Proximity.PeerFinder.TriggeredConnectionStateChanged, AddressOf TriggeredConnectionStateChanged
        ' Detach the incoming connection request event handler.
        RemoveHandler Windows.Networking.Proximity.PeerFinder.ConnectionRequested, AddressOf ConnectionRequested
        Windows.Networking.Proximity.PeerFinder.Stop()
        CloseSocket()
        _started = False
    End If
End Sub

' Write a message to MessageBlock on the UI thread.
Private Async Sub WriteMessageText(message As String, Optional overwrite As Boolean = False)
    Await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
        Sub()
            If overwrite Then
                MessageBlock.Text = message
            Else
                MessageBlock.Text &= message
            End If
        End Sub)
End Sub

Private _started As Boolean = False

' Click event handler for "Advertise" button.
Private Sub AdvertiseForPeersButton_Click()

    If _started Then
        WriteMessageText("You are already advertising for a connection." & vbCrLf)
        Return
    End If

    Windows.Networking.Proximity.PeerFinder.DisplayName = DisplayNameTextBox.Text

    If ((Windows.Networking.Proximity.PeerFinder.SupportedDiscoveryTypes And
         Windows.Networking.Proximity.PeerDiscoveryTypes.Triggered) =
         Windows.Networking.Proximity.PeerDiscoveryTypes.Triggered) Then

        AddHandler Windows.Networking.Proximity.PeerFinder.TriggeredConnectionStateChanged,
            AddressOf TriggeredConnectionStateChanged

        WriteMessageText("You can tap to connect a peer device that is " &
                         "also advertising for a connection." & vbCrLf)
    Else
        WriteMessageText("Tap to connect is not supported." & vbCrLf)
    End If

    If (Windows.Networking.Proximity.PeerFinder.SupportedDiscoveryTypes And
        Windows.Networking.Proximity.PeerDiscoveryTypes.Browse) <>
        Windows.Networking.Proximity.PeerDiscoveryTypes.Browse Then

        WriteMessageText("Peer discovery using Wifi-Direct is not supported." & vbCrLf)
    End If

    Windows.Networking.Proximity.PeerFinder.Start()
    _started = True
End Sub

Private Sub TriggeredConnectionStateChanged(
    sender As Object,
    e As Windows.Networking.Proximity.TriggeredConnectionStateChangedEventArgs)

    If e.State = Windows.Networking.Proximity.TriggeredConnectState.PeerFound Then

        WriteMessageText("Peer found. You may now pull your devices out of proximity." & vbCrLf)
    End If

    If e.State = Windows.Networking.Proximity.TriggeredConnectState.Completed Then
        WriteMessageText("Connected. You may now send a message." & vbCrLf)
        SendMessage(e.Socket)
    End If
End Sub

' Click event handler for "Browse" button.
Private Async Sub FindPeersButton_Click()
    If (Windows.Networking.Proximity.PeerFinder.SupportedDiscoveryTypes And
        Windows.Networking.Proximity.PeerDiscoveryTypes.Browse) <>
        Windows.Networking.Proximity.PeerDiscoveryTypes.Browse Then

        WriteMessageText("Peer discovery using Wifi-Direct is not supported." & vbCrLf)
        Return
    End If

    Try
        Dim peerInfoCollection = Await Windows.Networking.Proximity.PeerFinder.FindAllPeersAsync()
        If peerInfoCollection.Count > 0 Then
            ' Connect to first peer found - example only.
            ' In your app, provide the user with a list of available peers.
            ConnectToPeer(peerInfoCollection(0))
        End If
    Catch err As Exception
        WriteMessageText("Error finding peers: " & err.Message & vbCrLf)
    End Try
End Sub

Private Async Sub ConnectToPeer(peerInfo As Windows.Networking.Proximity.PeerInformation)

    WriteMessageText("Peer found. Connecting to " & peerInfo.DisplayName & vbCrLf)
    Try
        Dim socket = Await Windows.Networking.Proximity.PeerFinder.ConnectAsync(peerInfo)

        WriteMessageText("Connection successful. You may now send messages." & vbCrLf)
        SendMessage(socket)
    Catch err As Exception
        WriteMessageText("Connection failed: " & err.Message & vbCrLf)
    End Try

    requestingPeer = Nothing
End Sub

' Click event handler for "Stop" button.
Private Sub StopFindingPeersButton_Click()

    _started = False
    Windows.Networking.Proximity.PeerFinder.Stop()
    If proximitySocket IsNot Nothing Then CloseSocket()
End Sub

' Handle external connection requests.
Private requestingPeer As Windows.Networking.Proximity.PeerInformation

Private Sub ConnectionRequested(sender As Object,
    e As Windows.Networking.Proximity.ConnectionRequestedEventArgs)

    requestingPeer = e.PeerInformation

    WriteMessageText("Connection requested by " & requestingPeer.DisplayName & ". " &
        "Click 'Accept Connection' to connect.")
End Sub

Private Sub AcceptConnectionButton_Click()
    If requestingPeer Is Nothing Then
        WriteMessageText("No peer connection has been requested.")
        Return
    End If

    ConnectToPeer(requestingPeer)
End Sub

Remarks

You can call the Start method to begin the process of finding a peer app and to make your app discoverable to remote peers that call the FindAllPeersAsync method. A peer is a device that has an app running in the foreground with a matching AppId. A peer can also have a matching Browse Id that's specified as an alternate identity. For more information, see AlternateIdentities.

You can connect to only one peer at a time if your app is in the peer or client role. If your app is in the host role, you can connect up to 5 clients at a time.

When an app is activated by tapping a nearby device, the activation parameters indicate whether the PeerFinder should be started or if the app was launched with activation arguments. The format of the activation parameters is "Windows.Networking.Proximity.PeerFinder:StreamSocket Role=<Host|Client>". For more information, see the "Activating apps using Proximity" section of Supporting Proximity and Tapping.

Important

Always set the DisplayName property to a unique value for your app before you call the Start method.

Windows Phone 8

Wi-Fi Direct is not supported on Windows Phone 8.

Applies to

Start(String)

Edit

Makes an app discoverable to remote peers.

public:
 static void Start(Platform::String ^ peerMessage);

/// [Windows.Foundation.Metadata.Overload("StartWithMessage")]
 static void Start(winrt::hstring const& peerMessage);

[Windows.Foundation.Metadata.Overload("StartWithMessage")]
public static void Start(string peerMessage);

function start(peerMessage)

Public Shared Sub Start (peerMessage As String)

Parameters

peerMessage: String
Platform::String

winrt::hstring

The message to deliver to the proximate device.

Attributes: OverloadAttribute

Windows requirements

App capabilities

ID_CAP_NETWORKING [Windows Phone] proximity ID_CAP_PROXIMITY [Windows Phone]

Remarks

You can use this overload of the Start method to send a message to a peer app that will be passed as an app activation argument.

You can connect to only one peer at a time if your app is in the peer or client role. If your app is in the host role, you can connect up to 5 clients at a time.

Important

Always set the DisplayName property to a unique value for your app before you call the Start method.

Windows Phone 8

Wi-Fi Direct is not supported on Windows Phone 8.

Applies to

Delen via

PeerFinder.Start Method

Definition

Overloads

Start()

Windows requirements

Examples

Remarks

Windows Phone 8

See also

Applies to

Start(String)

Parameters

Windows requirements

Remarks

Windows Phone 8

See also

Applies to

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