ProximityDevice.PublishMessage 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

PublishMessage(String, String)	Publishes a message to subscribers of the specified message type.
PublishMessage(String, String, MessageTransmittedHandler)	Publishes a message to subscribers of the specified message type. The specified handler is called when the message has been transmitted.

PublishMessage(String, String)

Edit

Publishes a message to subscribers of the specified message type.

public:
 virtual long long PublishMessage(Platform::String ^ messageType, Platform::String ^ message) = PublishMessage;

/// [Windows.Foundation.Metadata.Overload("PublishMessage")]
long PublishMessage(winrt::hstring const& messageType, winrt::hstring const& message);

[Windows.Foundation.Metadata.Overload("PublishMessage")]
public long PublishMessage(string messageType, string message);

function publishMessage(messageType, message)

Public Function PublishMessage (messageType As String, message As String) As Long

Parameters

messageType: String
Platform::String

winrt::hstring

The type of message to deliver to subscribers.

message: String
Platform::String

winrt::hstring

The message to deliver to subscribers.

Returns

Int64

long long

long

A unique publication ID for the published message. Pass this value to the StopPublishingMessage method to stop publishing the message.

Attributes: OverloadAttribute

Windows requirements

App capabilities

ID_CAP_PROXIMITY [Windows Phone] proximity ID_CAP_PROXIMITY [Windows Phone]

Examples

Windows.Networking.Proximity.ProximityDevice proximityDevice;
long publishedMessageId = -1;
long subscribedMessageId = -1;

private void initializeProximityDevice()
{
    proximityDevice = Windows.Networking.Proximity.ProximityDevice.GetDefault();

    if (proximityDevice != null)
    {
        PublishMessageButton.Click += PublishMessage;
        SubscribeForMessageButton.Click += SubscribeForMessage;
        StopSubscribingForMessageButton.Click += StopSubscribingForMessage;
        StopPublishingMessageButton.Click += StopPublishingMessage;
    }
    else
    {
        WriteMessageText("Failed to initialized proximity device.\n");
    }
}

private void PublishMessage(object sender, RoutedEventArgs e)
{
    // Stop publishing the current message.
    if (publishedMessageId != -1)
    {
        proximityDevice.StopPublishingMessage(publishedMessageId);
    }

    publishedMessageId = 
        proximityDevice.PublishMessage("Windows.SampleMessage", MessageTextBlock.Text);
}

private void SubscribeForMessage(object sender, RoutedEventArgs e)
{
    // Only subscribe for the message one time.
    if (subscribedMessageId == -1)
    {
        subscribedMessageId = 
        proximityDevice.SubscribeForMessage("Windows.SampleMessage", messageReceived);
    }
}

private void messageReceived(
    Windows.Networking.Proximity.ProximityDevice device, 
    Windows.Networking.Proximity.ProximityMessage message)
{
    MessageBlock.Text += "Message received: " + message.DataAsString + "\n";
}

private void StopSubscribingForMessage(object sender, RoutedEventArgs e)
{
    proximityDevice.StopSubscribingForMessage(subscribedMessageId);
    subscribedMessageId = -1;
}

private void StopPublishingMessage(object sender, RoutedEventArgs e)
{
    proximityDevice.StopPublishingMessage(publishedMessageId);
    publishedMessageId = -1;
}

// 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;
        });
}

Private proximityDevice As Windows.Networking.Proximity.ProximityDevice
Private publishedMessageId As Long = -1
Private subscribedMessageId As Long = -1

Private Sub initializeProximityDevice()
    proximityDevice = Windows.Networking.Proximity.ProximityDevice.GetDefault()

    If proximityDevice IsNot Nothing Then
        AddHandler PublishMessageButton.Click, AddressOf PublishMessage
        AddHandler SubscribeForMessageButton.Click, AddressOf SubscribeForMessage
        AddHandler StopSubscribingForMessageButton.Click, AddressOf StopSubscribingForMessage
        AddHandler StopPublishingMessageButton.Click, AddressOf StopPublishingMessage
    Else
        WriteMessageText("Failed to initialized proximity device." & vbTab)
    End If
End Sub

Private Sub PublishMessage(sender As Object, e As RoutedEventArgs)
    ' Stop publishing the current message.
    If publishedMessageId <> -1 Then
        proximityDevice.StopPublishingMessage(publishedMessageId)
    End If

    publishedMessageId =
        proximityDevice.PublishMessage("Windows.SampleMessage", MessageTextBlock.Text)
End Sub

Private Sub SubscribeForMessage(sender As Object, e As RoutedEventArgs)
    ' Only subscribe for the message one time.
    If subscribedMessageId = -1 Then
        subscribedMessageId =
        proximityDevice.SubscribeForMessage("Windows.SampleMessage", AddressOf messageReceived)
    End If
End Sub

Private Sub messageReceived(
    device As Windows.Networking.Proximity.ProximityDevice,
    message As Windows.Networking.Proximity.ProximityMessage)

    MessageBlock.Text &= "Message received: " & message.DataAsString & vbTab
End Sub

Private Sub StopSubscribingForMessage(sender As Object, e As RoutedEventArgs)
    proximityDevice.StopSubscribingForMessage(subscribedMessageId)
    subscribedMessageId = -1
End Sub

Private Sub StopPublishingMessage(sender As Object, e As RoutedEventArgs)
    proximityDevice.StopPublishingMessage(publishedMessageId)
    publishedMessageId = -1
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

Remarks

You can subscribe to published messages by using the SubscribeForMessage method.

Messages continue to be published until the StopPublishingMessage method is called or the ProximityDevice object is released.

Messages are delivered to all applications that have subscribed to the message type (as indicated by the messageType parameter). Message type values are case-sensitive strings that consist of two parts: the protocol and the subtype. The protocol is first, followed by a dot (.) and then the subtype. For the PublishMessage method, the protocol must always be "Windows.". The subtype is a string of alphanumeric characters and the following additional characters: . ( ) + , - : = @ ; $ _ ! * '. The subtype cannot exceed a length of 250 characters.

To publish messages by using another message type, like "WindowsMime." or "NDEF:WriteTag", you must use the PublishBinaryMessage method.

You can use the PublishUriMessage method to publish a Uniform Resource Identifier (URI) to a proximate computer.

Messages are converted to UTF-8 characters before they're transmitted.

For UWP apps, publications and subscriptions are active only if the calling app is in the foreground.

Important

The proximity APIs do not provide authentication, encryption, or message integrity. Do not use proximity to exchange user sensitive information such as passwords, financial data, text messages, email, photographs, or government id numbers.

Applies to

PublishMessage(String, String, MessageTransmittedHandler)

Edit

Publishes a message to subscribers of the specified message type. The specified handler is called when the message has been transmitted.

public:
 virtual long long PublishMessage(Platform::String ^ messageType, Platform::String ^ message, MessageTransmittedHandler ^ messageTransmittedHandler) = PublishMessage;

/// [Windows.Foundation.Metadata.Overload("PublishMessageWithCallback")]
long PublishMessage(winrt::hstring const& messageType, winrt::hstring const& message, MessageTransmittedHandler const& messageTransmittedHandler);

[Windows.Foundation.Metadata.Overload("PublishMessageWithCallback")]
public long PublishMessage(string messageType, string message, MessageTransmittedHandler messageTransmittedHandler);

function publishMessage(messageType, message, messageTransmittedHandler)

Public Function PublishMessage (messageType As String, message As String, messageTransmittedHandler As MessageTransmittedHandler) As Long

Parameters

messageType: String
Platform::String

winrt::hstring

The type of message to deliver to subscribers.

message: String
Platform::String

winrt::hstring

The message to deliver to subscribers.

messageTransmittedHandler: MessageTransmittedHandler

The handler to call when the message has been transmitted.

Returns

Int64

long long

long

A unique publication ID for the published message.

Attributes: OverloadAttribute

Windows requirements

App capabilities

ID_CAP_PROXIMITY [Windows Phone] proximity ID_CAP_PROXIMITY [Windows Phone]

Examples

    Windows.Networking.Proximity.ProximityDevice proximityDevice;
    long publishedMessageId = -1;
    long subscribedMessageId = -1;

    private void initializeProximityDevice()
    {
        proximityDevice = Windows.Networking.Proximity.ProximityDevice.GetDefault();

        if (proximityDevice != null)
        {
            PublishMessageButton.Click += PublishMessage;
            SubscribeForMessageButton.Click += SubscribeForMessage;
            StopSubscribingForMessageButton.Click += StopSubscribingForMessage;
            StopPublishingMessageButton.Click += StopPublishingMessage;
        }
        else
        {
            WriteMessageText("Failed to initialized proximity device.\n");
        }
    }

    private void PublishMessage(object sender, RoutedEventArgs e)
    {
        // Stop publishing the current message.
        if (publishedMessageId != -1)
        {
            proximityDevice.StopPublishingMessage(publishedMessageId);
        }

        publishedMessageId = 
            proximityDevice.PublishMessage("Windows.SampleMessage", MessageTextBlock.Text,
                                                   MessagePublished);
    }

private void MessagePublished(
    Windows.Networking.Proximity.ProximityDevice sender,
        long messageId)
    {
    // The message has been successfully published.
    }

    private void SubscribeForMessage(object sender, RoutedEventArgs e)
    {
        // Only subscribe for the message one time.
        if (subscribedMessageId == -1)
        {
            subscribedMessageId = 
            proximityDevice.SubscribeForMessage("Windows.SampleMessage", messageReceived);
        }
    }

    private void messageReceived(
        Windows.Networking.Proximity.ProximityDevice device, 
        Windows.Networking.Proximity.ProximityMessage message)
    {
        MessageBlock.Text += "Message received: " + message.DataAsString + "\n";
    }

    private void StopSubscribingForMessage(object sender, RoutedEventArgs e)
    {
        proximityDevice.StopSubscribingForMessage(subscribedMessageId);
        subscribedMessageId = -1;
    }

    private void StopPublishingMessage(object sender, RoutedEventArgs e)
    {
        proximityDevice.StopPublishingMessage(publishedMessageId);
        publishedMessageId = -1;
    }

    // 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;
            });
    }

Private proximityDevice As Windows.Networking.Proximity.ProximityDevice
Private publishedMessageId As Long = -1
Private subscribedMessageId As Long = -1

Private Sub initializeProximityDevice()
    proximityDevice = Windows.Networking.Proximity.ProximityDevice.GetDefault()

    If proximityDevice IsNot Nothing Then
        AddHandler PublishMessageButton.Click, AddressOf PublishMessage
        AddHandler SubscribeForMessageButton.Click, AddressOf SubscribeForMessage
        AddHandler StopSubscribingForMessageButton.Click, AddressOf StopSubscribingForMessage
        AddHandler StopPublishingMessageButton.Click, AddressOf StopPublishingMessage
    Else
        WriteMessageText("Failed to initialized proximity device." & vbTab)
    End If
End Sub

Private Sub PublishMessage(sender As Object, e As RoutedEventArgs)
    ' Stop publishing the current message.
    If publishedMessageId <> -1 Then
        proximityDevice.StopPublishingMessage(publishedMessageId)
    End If

    publishedMessageId =
        proximityDevice.PublishMessage("Windows.SampleMessage", MessageTextBlock.Text,
                                       AddressOf MessagePublished)
End Sub

Private Sub MessagePublished(
sender As Windows.Networking.Proximity.ProximityDevice,
    messageId As Long)

' The message has been successfully published.
End Sub

Private Sub SubscribeForMessage(sender As Object, e As RoutedEventArgs)
    ' Only subscribe for the message one time.
    If subscribedMessageId = -1 Then
        subscribedMessageId =
        proximityDevice.SubscribeForMessage("Windows.SampleMessage", AddressOf messageReceived)
    End If
End Sub

Private Sub messageReceived(
    device As Windows.Networking.Proximity.ProximityDevice,
    message As Windows.Networking.Proximity.ProximityMessage)

    MessageBlock.Text &= "Message received: " & message.DataAsString & vbTab
End Sub

Private Sub StopSubscribingForMessage(sender As Object, e As RoutedEventArgs)
    proximityDevice.StopSubscribingForMessage(subscribedMessageId)
    subscribedMessageId = -1
End Sub

Private Sub StopPublishingMessage(sender As Object, e As RoutedEventArgs)
    proximityDevice.StopPublishingMessage(publishedMessageId)
    publishedMessageId = -1
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

Remarks

You can subscribe to published messages by using the SubscribeForMessage method.

Messages continue to be published until the StopPublishingMessage method is called or the ProximityDevice object is released.

To publish messages by using another message type, like "WindowsMime." or "NDEF:WriteTag", you must use the PublishBinaryMessage method.

You can use the PublishUriMessage method to publish a Uniform Resource Identifier (URI) to a proximate computer.

Messages are converted to UTF-8 characters before they're transmitted.

For UWP apps, publications and subscriptions are active only if the calling app is in the foreground.

Important

Applies to

ProximityDevice.PublishMessage Method

Definition

Overloads

PublishMessage(String, String)

Parameters

Returns

Windows requirements

Examples

Remarks

See also

Applies to

PublishMessage(String, String, MessageTransmittedHandler)

Parameters

Returns

Windows requirements

Examples

Remarks

See also

Applies to

Feedback

Feedback

Additional resources