BLEServer Component

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An easy-to-use Bluetooth Low Energy (BLE) GATT Server component.

Syntax

nsoftware.IPWorksBLE.BLEServer

Remarks

The BLEServer component provides a simple but flexible BLE GATT server (peripheral) implementation, making it easy to advertise your own services and characteristics, and to respond to the requests of remote BLE GATT clients that connect to them.

Prerequisites

Windows Notes:

Please note that the BLE components are only supported by Windows 10 Creator's Update (10.0.15063.0) and later. Additionally .NET Version 4.5 or higher is required.

Android Notes:

The BLE components require an Android API level of 21 or higher.

Note that on Android, even when pairing is not explicitly enabled in the component, the operating system may automatically perform pairing as it deems appropriate.

iOS/macOS Notes:

The BLE components have the following operating system requirements:

• iOS 5.0+
• iPadOS 5.0+
• Mac Catalyst 13.0+
• macOS 10.10+

Linux Notes:

On Linux, the BLE components rely on BlueZ and DBus. These packages must be installed in order to use the components. Many Linux distributions come with BlueZ and DBus pre-installed.

Adding Services and Characteristics

As with BLEClient, UUIDs may be given as 16-, 32-, or 128-bit hexadecimal strings (a mixture of formats is fine; they're all converted to 128-bit internally).

Props is a bitmask made up of one or more of the following flags:

• 0x0002 (Read): The characteristic's value may be read by clients. Handle the ReadRequested event to supply the value.
• 0x0004 (WriteWithoutResponse): Clients may write the characteristic's value without expecting an acknowledgement.
• 0x0008 (Write): Clients may write the characteristic's value and receive an acknowledgement indicating success or failure.
• 0x0010 (Notify): Clients may subscribe to receive unacknowledged notifications when the characteristic's value changes.
• 0x0020 (Indicate): Clients may subscribe to receive acknowledged indications when the characteristic's value changes.

// Add a simple read-only "Battery Level" characteristic to a "Battery Service". bleserver1.AddCharacteristic("180F", "2A19", 0x0002);

Refer to AddCharacteristic for more detailed information.

Advertising

You can check whether a particular service is currently being advertised by setting the ServiceId property to its UUID, and then inspecting the Listening property. Call StopListening to stop advertising a service.

// AdvertisementStatusChanged event handler. bleserver1.OnAdvertisementStatusChanged += (s, e) => Console.WriteLine("Advertising status: " + e.Status); bleserver1.StartListening("180F"); // ... bleserver1.StopListening("180F");

Handling Client Requests

Handle the ReadRequested event to respond to read requests for characteristics that have the Read flag set. Set the event's ResponseValue parameter to a hex-encoded string holding the bytes to return, and leave its Accept parameter set to its default value of True. To reject the request instead, set Accept to False.

bleserver1.OnReadRequested += (s, e) => { if (e.CharacteristicId.Equals("00002A19-0000-1000-8000-00805F9B34FB", StringComparison.OrdinalIgnoreCase)) { e.ResponseValue = "5A"; // 90 (%), as a single hex-encoded byte. } else { e.Accept = false; } };

Similarly, handle the WriteRequested event to respond to write requests for characteristics that have the Write or WriteWithoutResponse flag set. Its Value parameter holds the hex-encoded string of bytes the client wants to write, and WithResponse indicates whether the client is expecting an acknowledgement. Set Accept to False to reject a write made with acknowledgement; Accept has no effect on writes made without acknowledgement, since the client isn't told the outcome either way.

bleserver1.OnWriteRequested += (s, e) => { Console.WriteLine("Client wrote: " + e.Value); };

Handle the SubscriptionChanged event to know when a Notify or Indicate characteristic gains or loses subscribed clients, and the SessionStatusChanged and Disconnected events to track a client's connection over time.

Once a client has subscribed to a Notify or Indicate characteristic, call UpdateValue whenever its value changes to push the new value to every currently subscribed client. If no clients are currently subscribed, calling UpdateValue has no effect.

// Push a new value to all clients subscribed to notifications/indications on this characteristic. bleserver1.UpdateValue("180F", "2A19", new byte[] { 0x5A });

Usage Notes

Most platforms will in some way limit the use of Bluetooth APIs when your application is in the background. Be aware of the limitations your platform places on the usage of BLE APIs while in the background, and be ready to act accordingly.

Be sure to call StopListening for each of your services when you're finished advertising them.

Property List

The following is the full list of the properties of the component with short descriptions. Click on the links for further details.

Method List

The following is the full list of the methods of the component with short descriptions. Click on the links for further details.

Event List

The following is the full list of the events fired by the component with short descriptions. Click on the links for further details.

Config Settings

The following is a list of config settings for the component with short descriptions. Click on the links for further details.

Characteristics Property (BLEServer Component)

The GATT characteristics which have been added to the server.

Syntax

• C#
• VB.NET

public ServerCharacteristicList Characteristics { get; }
                

Public ReadOnly Property Characteristics As ServerCharacteristicList
                

Remarks

The GATT characteristics which have been added to the server through calls to the AddCharacteristic method. This collection is read-only.

This property is read-only and not available at design time.

Listening Property (BLEServer Component)

Whether the service identified by ServiceId is currently being advertised.

Syntax

• C#
• VB.NET

public bool Listening { get; }
                

Public ReadOnly Property Listening As Boolean
                

Default Value

False

Remarks

This property indicates whether the service identified by the ServiceId property is currently being advertised, and can therefore be discovered by remote clients.

Use the StartListening and StopListening methods to start and stop advertising a service.

This property is read-only and not available at design time.

ServiceId Property (BLEServer Component)

The Id of the service to check the listening status of.

Syntax

• C#
• VB.NET

public string ServiceId { get; set; }
                

Public Property ServiceId As String
                

Default Value

""

Remarks

Set ServiceId to the Id of a service you've added characteristics to (via AddCharacteristic) in order to inspect its advertising status using the Listening property.

Services are identified by the same UUID string passed to AddCharacteristic, StartListening, and StopListening.

This property is not available at design time.

Services Property (BLEServer Component)

The GATT services which have been added to the server.

Syntax

• C#
• VB.NET

public ServerServiceList Services { get; }
                

Public ReadOnly Property Services As ServerServiceList
                

Remarks

The GATT services which have been added to the server through calls to the AddCharacteristic method. This collection is read-only.

This property is read-only and not available at design time.

AddCharacteristic Method (BLEServer Component)

Adds a characteristic to a service, creating the service if necessary.

Syntax

• C#
• VB.NET

public void AddCharacteristic(string serviceId, string characteristicId, int props);

Async Version
public async Task AddCharacteristic(string serviceId, string characteristicId, int props);
public async Task AddCharacteristic(string serviceId, string characteristicId, int props, CancellationToken cancellationToken);
                

Public Sub AddCharacteristic(ByVal ServiceId As String, ByVal CharacteristicId As String, ByVal Props As Integer)

Async Version
Public Sub AddCharacteristic(ByVal ServiceId As String, ByVal CharacteristicId As String, ByVal Props As Integer) As Task
Public Sub AddCharacteristic(ByVal ServiceId As String, ByVal CharacteristicId As String, ByVal Props As Integer, cancellationToken As CancellationToken) As Task
                

Remarks

This method adds a characteristic, identified by CharacteristicId, to the service identified by ServiceId. If no service with that Id has been added yet, it is created automatically.

ServiceId and CharacteristicId are UUID strings, and may be specified using 16-, 32-, or 128-bit hexadecimal notation (dashes are optional); they are converted to full 128-bit UUIDs internally.

Props is a bitmask describing the operations remote clients are permitted to perform on the characteristic once it starts being advertised. It should be one or more of the following flags, combined with a bitwise OR:

A characteristic cannot be added to a service that is already being advertised (see StartListening); doing so will cause the component to throws an exception. Once a service has started listening, its set of characteristics is fixed until you call StopListening.

// Add a read-only "Battery Level" characteristic to a "Battery Service". bleserver1.AddCharacteristic("180F", "2A19", 0x0002); // Add a write-only "Alert Level" characteristic to an "Immediate Alert" service. bleserver1.AddCharacteristic("1802", "2A06", 0x0008);

Config Method (BLEServer Component)

Sets or retrieves a configuration setting.

Syntax

• C#
• VB.NET

public string Config(string configurationString);

Async Version
public async Task<string> Config(string configurationString);
public async Task<string> Config(string configurationString, CancellationToken cancellationToken);
                

Public Function Config(ByVal ConfigurationString As String) As String

Async Version
Public Function Config(ByVal ConfigurationString As String) As Task(Of String)
Public Function Config(ByVal ConfigurationString As String, cancellationToken As CancellationToken) As Task(Of String)
                

Remarks

Config is a generic method available in every component. It is used to set and retrieve configuration settings for the component.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

DoEvents Method (BLEServer Component)

This method processes events from the internal message queue.

Syntax

• C#
• VB.NET

public void DoEvents();

Async Version
public async Task DoEvents();
public async Task DoEvents(CancellationToken cancellationToken);
                

Public Sub DoEvents()

Async Version
Public Sub DoEvents() As Task
Public Sub DoEvents(cancellationToken As CancellationToken) As Task
                

Remarks

When DoEvents is called, the component processes any available events. If no events are available, it waits for a preset period of time, and then returns.

StartListening Method (BLEServer Component)

Begins advertising a service so that remote clients can discover and connect to it.

Syntax

• C#
• VB.NET

public void StartListening(string serviceId);

Async Version
public async Task StartListening(string serviceId);
public async Task StartListening(string serviceId, CancellationToken cancellationToken);
                

Public Sub StartListening(ByVal ServiceId As String)

Async Version
Public Sub StartListening(ByVal ServiceId As String) As Task
Public Sub StartListening(ByVal ServiceId As String, cancellationToken As CancellationToken) As Task
                

Remarks

This method begins advertising the service identified by ServiceId, making it discoverable by nearby GATT clients. ServiceId must identify a service that characteristics have already been added to via AddCharacteristic.

The AdvertisementStatusChanged event fires once advertising actually starts (and again if it later stops or is aborted). You can check whether a service is currently being advertised at any time by setting the ServiceId property to its Id and inspecting the Listening property.

Calling this method for a service that doesn't exist, or that is already being advertised, will cause the component to throws an exception.

bleserver1.AddCharacteristic("180F", "2A19", 0x0002); bleserver1.StartListening("180F");

StopListening Method (BLEServer Component)

Stops advertising a service.

Syntax

• C#
• VB.NET

public void StopListening(string serviceId);

Async Version
public async Task StopListening(string serviceId);
public async Task StopListening(string serviceId, CancellationToken cancellationToken);
                

Public Sub StopListening(ByVal ServiceId As String)

Async Version
Public Sub StopListening(ByVal ServiceId As String) As Task
Public Sub StopListening(ByVal ServiceId As String, cancellationToken As CancellationToken) As Task
                

Remarks

This method stops advertising the service identified by ServiceId.

The AdvertisementStatusChanged event fires once advertising has actually stopped.

Calling this method for a service that doesn't exist, or that isn't currently being advertised, will cause the component to throws an exception.

bleserver1.StopListening("180F");

UpdateValue Method (BLEServer Component)

Updates the value of a characteristic and sends a notification or indication to all currently subscribed clients.

Syntax

• C#
• VB.NET

public void UpdateValue(string serviceId, string characteristicId, byte[] value);

Async Version
public async Task UpdateValue(string serviceId, string characteristicId, byte[] value);
public async Task UpdateValue(string serviceId, string characteristicId, byte[] value, CancellationToken cancellationToken);
                

Public Sub UpdateValue(ByVal ServiceId As String, ByVal CharacteristicId As String, ByVal Value As Byte())

Async Version
Public Sub UpdateValue(ByVal ServiceId As String, ByVal CharacteristicId As String, ByVal Value As Byte()) As Task
Public Sub UpdateValue(ByVal ServiceId As String, ByVal CharacteristicId As String, ByVal Value As Byte(), cancellationToken As CancellationToken) As Task
                

Remarks

This method broadcasts a value to all subscribed clients. It does not target a specific client.

The value is specified as a byte array. The characteristic must support notifications or indications. If no clients are subscribed, no notification is sent.

Calling this method for a service that is not currently being advertised will cause the component to throws an exception.

AdvertisementStatusChanged Event (BLEServer Component)

Fired when the advertising status of a service changes.

Syntax

• C#
• VB.NET

public event OnAdvertisementStatusChangedHandler OnAdvertisementStatusChanged;

public delegate void OnAdvertisementStatusChangedHandler(object sender, BLEServerAdvertisementStatusChangedEventArgs e);

public class BLEServerAdvertisementStatusChangedEventArgs : EventArgs {
  public int Status { get; }
  public int Error { get; }
}

Async Version
public event AsyncEventHandler<BLEServerAdvertisementStatusChangedEventArgs> OnAdvertisementStatusChanged;

public delegate Task AsyncEventHandler<TEventArgs>(object sender, TEventArgs e);

public class BLEServerAdvertisementStatusChangedEventArgs : AsyncEventArgs {
  public CancellationToken CancellationToken { get; }
  public int Status { get; }
  public int Error { get; }
}
                

Public Event OnAdvertisementStatusChanged As OnAdvertisementStatusChangedHandler

Public Delegate Sub OnAdvertisementStatusChangedHandler(sender As Object, e As BLEServerAdvertisementStatusChangedEventArgs)

Public Class BLEServerAdvertisementStatusChangedEventArgs Inherits EventArgs
  Public ReadOnly Property Status As Integer
  Public ReadOnly Property Error As Integer
End Class

Async Version
Public Event OnAdvertisementStatusChanged As AsyncEventHandler(Of BLEServerAdvertisementStatusChangedEventArgs)

Public Delegate Function AsyncEventHandler(Of TEventArgs)(sender As Object, e As TEventArgs) As Task

Public Class BLEServerAdvertisementStatusChangedEventArgs Inherits AsyncEventArgs
  Public ReadOnly Property CancellationToken As CancellationToken
  Public ReadOnly Property Status As Integer
  Public ReadOnly Property Error As Integer
End Class
                

Remarks

This event fires in response to StartListening and StopListening, and also if advertising is unexpectedly aborted by the underlying Bluetooth stack (for example, because the adapter was disabled).

Status indicates whether advertising has started, stopped, or was aborted; Error holds the underlying Bluetooth-stack error code if Status indicates an abort, or 0 otherwise. The exact numeric values used for Status are platform-dependent.

Note that this event does not identify which service's advertising status has changed. If you are advertising more than one service at a time, set the ServiceId property to each of your service Ids in turn and check the Listening property to determine which one this event pertains to.

Connected Event (BLEServer Component)

Fired when a remote client connects.

Syntax

• C#
• VB.NET

public event OnConnectedHandler OnConnected;

public delegate void OnConnectedHandler(object sender, BLEServerConnectedEventArgs e);

public class BLEServerConnectedEventArgs : EventArgs {
  public string ClientId { get; }
  public int StatusCode { get; }
  public string Description { get; }
}

Async Version
public event AsyncEventHandler<BLEServerConnectedEventArgs> OnConnected;

public delegate Task AsyncEventHandler<TEventArgs>(object sender, TEventArgs e);

public class BLEServerConnectedEventArgs : AsyncEventArgs {
  public CancellationToken CancellationToken { get; }
  public string ClientId { get; }
  public int StatusCode { get; }
  public string Description { get; }
}
                

Public Event OnConnected As OnConnectedHandler

Public Delegate Sub OnConnectedHandler(sender As Object, e As BLEServerConnectedEventArgs)

Public Class BLEServerConnectedEventArgs Inherits EventArgs
  Public ReadOnly Property ClientId As String
  Public ReadOnly Property StatusCode As Integer
  Public ReadOnly Property Description As String
End Class

Async Version
Public Event OnConnected As AsyncEventHandler(Of BLEServerConnectedEventArgs)

Public Delegate Function AsyncEventHandler(Of TEventArgs)(sender As Object, e As TEventArgs) As Task

Public Class BLEServerConnectedEventArgs Inherits AsyncEventArgs
  Public ReadOnly Property CancellationToken As CancellationToken
  Public ReadOnly Property ClientId As String
  Public ReadOnly Property StatusCode As Integer
  Public ReadOnly Property Description As String
End Class
                

Remarks

The underlying Bluetooth APIs do not notify the component when a remote device forms a low-level BLE connection to it. Instead, this event fires the first time a client interacts with one of your characteristics, by reading it (ReadRequested), writing it (WriteRequested), or subscribing to it (SubscriptionChanged).

ClientId is a platform-specific string that identifies the client, and is also provided as a parameter to the events above, as well as SessionStatusChanged and Disconnected, so that you can associate requests with a particular client.

StatusCode is always 0 and Description is always "OK", since a connection has, by definition, already been established by the time this event can fire.

Disconnected Event (BLEServer Component)

Fired when a connected client disconnects.

Syntax

• C#
• VB.NET

public event OnDisconnectedHandler OnDisconnected;

public delegate void OnDisconnectedHandler(object sender, BLEServerDisconnectedEventArgs e);

public class BLEServerDisconnectedEventArgs : EventArgs {
  public string ClientId { get; }
  public int StatusCode { get; }
  public string Description { get; }
}

Async Version
public event AsyncEventHandler<BLEServerDisconnectedEventArgs> OnDisconnected;

public delegate Task AsyncEventHandler<TEventArgs>(object sender, TEventArgs e);

public class BLEServerDisconnectedEventArgs : AsyncEventArgs {
  public CancellationToken CancellationToken { get; }
  public string ClientId { get; }
  public int StatusCode { get; }
  public string Description { get; }
}
                

Public Event OnDisconnected As OnDisconnectedHandler

Public Delegate Sub OnDisconnectedHandler(sender As Object, e As BLEServerDisconnectedEventArgs)

Public Class BLEServerDisconnectedEventArgs Inherits EventArgs
  Public ReadOnly Property ClientId As String
  Public ReadOnly Property StatusCode As Integer
  Public ReadOnly Property Description As String
End Class

Async Version
Public Event OnDisconnected As AsyncEventHandler(Of BLEServerDisconnectedEventArgs)

Public Delegate Function AsyncEventHandler(Of TEventArgs)(sender As Object, e As TEventArgs) As Task

Public Class BLEServerDisconnectedEventArgs Inherits AsyncEventArgs
  Public ReadOnly Property CancellationToken As CancellationToken
  Public ReadOnly Property ClientId As String
  Public ReadOnly Property StatusCode As Integer
  Public ReadOnly Property Description As String
End Class
                

Remarks

This event fires when the GATT session for a previously-connected client (see Connected) is closed; refer to SessionStatusChanged for more information about session state changes.

ClientId identifies which client disconnected. StatusCode is always 0 and Description is always "OK".

If the disconnecting client had any active characteristic subscriptions, the SubscriptionChanged event will fire separately to reflect their removal.

Error Event (BLEServer Component)

Fired when information is available about errors during data delivery.

Syntax

• C#
• VB.NET

public event OnErrorHandler OnError;

public delegate void OnErrorHandler(object sender, BLEServerErrorEventArgs e);

public class BLEServerErrorEventArgs : EventArgs {
  public int ErrorCode { get; }
  public string Description { get; }
}

Async Version
public event AsyncEventHandler<BLEServerErrorEventArgs> OnError;

public delegate Task AsyncEventHandler<TEventArgs>(object sender, TEventArgs e);

public class BLEServerErrorEventArgs : AsyncEventArgs {
  public CancellationToken CancellationToken { get; }
  public int ErrorCode { get; }
  public string Description { get; }
}
                

Public Event OnError As OnErrorHandler

Public Delegate Sub OnErrorHandler(sender As Object, e As BLEServerErrorEventArgs)

Public Class BLEServerErrorEventArgs Inherits EventArgs
  Public ReadOnly Property ErrorCode As Integer
  Public ReadOnly Property Description As String
End Class

Async Version
Public Event OnError As AsyncEventHandler(Of BLEServerErrorEventArgs)

Public Delegate Function AsyncEventHandler(Of TEventArgs)(sender As Object, e As TEventArgs) As Task

Public Class BLEServerErrorEventArgs Inherits AsyncEventArgs
  Public ReadOnly Property CancellationToken As CancellationToken
  Public ReadOnly Property ErrorCode As Integer
  Public ReadOnly Property Description As String
End Class
                

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the component throws an exception.

The ErrorCode parameter contains an error code, and the Description parameter contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

Log Event (BLEServer Component)

Fires once for each log message.

Syntax

• C#
• VB.NET

public event OnLogHandler OnLog;

public delegate void OnLogHandler(object sender, BLEServerLogEventArgs e);

public class BLEServerLogEventArgs : EventArgs {
  public int LogLevel { get; }
  public string Message { get; }
  public string LogType { get; }
}

Async Version
public event AsyncEventHandler<BLEServerLogEventArgs> OnLog;

public delegate Task AsyncEventHandler<TEventArgs>(object sender, TEventArgs e);

public class BLEServerLogEventArgs : AsyncEventArgs {
  public CancellationToken CancellationToken { get; }
  public int LogLevel { get; }
  public string Message { get; }
  public string LogType { get; }
}
                

Public Event OnLog As OnLogHandler

Public Delegate Sub OnLogHandler(sender As Object, e As BLEServerLogEventArgs)

Public Class BLEServerLogEventArgs Inherits EventArgs
  Public ReadOnly Property LogLevel As Integer
  Public ReadOnly Property Message As String
  Public ReadOnly Property LogType As String
End Class

Async Version
Public Event OnLog As AsyncEventHandler(Of BLEServerLogEventArgs)

Public Delegate Function AsyncEventHandler(Of TEventArgs)(sender As Object, e As TEventArgs) As Task

Public Class BLEServerLogEventArgs Inherits AsyncEventArgs
  Public ReadOnly Property CancellationToken As CancellationToken
  Public ReadOnly Property LogLevel As Integer
  Public ReadOnly Property Message As String
  Public ReadOnly Property LogType As String
End Class
                

Remarks

This events fires once for each log message generated by the component. The verbosity is controlled by the LogLevel setting.

LogLevel indicates the level of the Message. Possible values are:

The default log level, Info, provides information when most BLE operations begin and end, and should be sufficient to get a good idea of what the component is doing at a high level.

The Verbose log level adds a few extra operation timing messages, and adds more detail to some messages logged at the Info level.

The Debug log level causes the component to output as much information as possible about what it is doing at all times. All BLE communications, even those which are typically abstracted away by the API, are logged in full detail. Typically the additional information added by this log level is not helpful to the end user, and would only be necessary to capture if you wish to report an issue to the support team.

LogType identifies the type of log entry. Possible values are:

• Connection: Messages relating to connecting, disconnecting, and connection failures.
• Read: Messages relating to reading values from the remote device.
• Write: Messages relating to writing values to the remote device.
• Subscriptions: Messages relating to subscribing to and unsubscribing from characteristics.
• Info, Verbose, and Debug: Miscellaneous messages fired at the applicable log level concerning internal component operations.

ReadRequested Event (BLEServer Component)

Fired when a client requests to read a characteristic's value.

Syntax

• C#
• VB.NET

public event OnReadRequestedHandler OnReadRequested;

public delegate void OnReadRequestedHandler(object sender, BLEServerReadRequestedEventArgs e);

public class BLEServerReadRequestedEventArgs : EventArgs {
  public string ClientId { get; }
  public string ServiceId { get; }
  public string CharacteristicId { get; }
  public string ResponseValue { get; set; }
  public bool Accept { get; set; }
}

Async Version
public event AsyncEventHandler<BLEServerReadRequestedEventArgs> OnReadRequested;

public delegate Task AsyncEventHandler<TEventArgs>(object sender, TEventArgs e);

public class BLEServerReadRequestedEventArgs : AsyncEventArgs {
  public CancellationToken CancellationToken { get; }
  public string ClientId { get; }
  public string ServiceId { get; }
  public string CharacteristicId { get; }
  public string ResponseValue { get; set; }
  public bool Accept { get; set; }
}
                

Public Event OnReadRequested As OnReadRequestedHandler

Public Delegate Sub OnReadRequestedHandler(sender As Object, e As BLEServerReadRequestedEventArgs)

Public Class BLEServerReadRequestedEventArgs Inherits EventArgs
  Public ReadOnly Property ClientId As String
  Public ReadOnly Property ServiceId As String
  Public ReadOnly Property CharacteristicId As String
  Public Property ResponseValue As String
  Public Property Accept As Boolean
End Class

Async Version
Public Event OnReadRequested As AsyncEventHandler(Of BLEServerReadRequestedEventArgs)

Public Delegate Function AsyncEventHandler(Of TEventArgs)(sender As Object, e As TEventArgs) As Task

Public Class BLEServerReadRequestedEventArgs Inherits AsyncEventArgs
  Public ReadOnly Property CancellationToken As CancellationToken
  Public ReadOnly Property ClientId As String
  Public ReadOnly Property ServiceId As String
  Public ReadOnly Property CharacteristicId As String
  Public Property ResponseValue As String
  Public Property Accept As Boolean
End Class
                

Remarks

This event fires when a connected client sends a request to read the current value of a characteristic that was added (via AddCharacteristic) with the Read flag set.

ClientId identifies the requesting client, and ServiceId and CharacteristicId identify the characteristic being read.

To answer the request, set ResponseValue to a hex-encoded string representing the bytes to return to the client, and leave Accept set to its default value of True. If you do not set ResponseValue, an empty value is returned. To reject the request instead (for example, if the value isn't currently available), set Accept to False.

bleserver1.OnReadRequested += (s, e) => { if (e.CharacteristicId.Equals("00002A19-0000-1000-8000-00805F9B34FB", StringComparison.OrdinalIgnoreCase)) { // Battery Level characteristic: respond with 90%, encoded as a single hex byte. e.ResponseValue = "5A"; } else { e.Accept = false; } };

SessionStatusChanged Event (BLEServer Component)

Fired when a connected client's GATT session status changes.

Syntax

• C#
• VB.NET

public event OnSessionStatusChangedHandler OnSessionStatusChanged;

public delegate void OnSessionStatusChangedHandler(object sender, BLEServerSessionStatusChangedEventArgs e);

public class BLEServerSessionStatusChangedEventArgs : EventArgs {
  public string ClientId { get; }
  public int Status { get; }
  public int Error { get; }
}

Async Version
public event AsyncEventHandler<BLEServerSessionStatusChangedEventArgs> OnSessionStatusChanged;

public delegate Task AsyncEventHandler<TEventArgs>(object sender, TEventArgs e);

public class BLEServerSessionStatusChangedEventArgs : AsyncEventArgs {
  public CancellationToken CancellationToken { get; }
  public string ClientId { get; }
  public int Status { get; }
  public int Error { get; }
}
                

Public Event OnSessionStatusChanged As OnSessionStatusChangedHandler

Public Delegate Sub OnSessionStatusChangedHandler(sender As Object, e As BLEServerSessionStatusChangedEventArgs)

Public Class BLEServerSessionStatusChangedEventArgs Inherits EventArgs
  Public ReadOnly Property ClientId As String
  Public ReadOnly Property Status As Integer
  Public ReadOnly Property Error As Integer
End Class

Async Version
Public Event OnSessionStatusChanged As AsyncEventHandler(Of BLEServerSessionStatusChangedEventArgs)

Public Delegate Function AsyncEventHandler(Of TEventArgs)(sender As Object, e As TEventArgs) As Task

Public Class BLEServerSessionStatusChangedEventArgs Inherits AsyncEventArgs
  Public ReadOnly Property CancellationToken As CancellationToken
  Public ReadOnly Property ClientId As String
  Public ReadOnly Property Status As Integer
  Public ReadOnly Property Error As Integer
End Class
                

Remarks

This event fires whenever the underlying GATT session for a connected client (see Connected) becomes active or is closed. It may fire more than once for the same client over the lifetime of a connection, for instance if the client temporarily goes out of range.

ClientId identifies the client. Status indicates whether the session is now active or closed (the exact numeric values used are platform-dependent). Error holds the underlying Bluetooth-stack error code associated with the change, or 0 if there isn't one.

When Status indicates that a client's session has closed, the Disconnected event fires immediately afterward for the same client.

SubscriptionChanged Event (BLEServer Component)

Fired when a characteristic gains or loses a subscribed client.

Syntax

• C#
• VB.NET

public event OnSubscriptionChangedHandler OnSubscriptionChanged;

public delegate void OnSubscriptionChangedHandler(object sender, BLEServerSubscriptionChangedEventArgs e);

public class BLEServerSubscriptionChangedEventArgs : EventArgs {
  public string ServiceId { get; }
  public string CharacteristicId { get; }
  public bool IsSubscribed { get; }
}

Async Version
public event AsyncEventHandler<BLEServerSubscriptionChangedEventArgs> OnSubscriptionChanged;

public delegate Task AsyncEventHandler<TEventArgs>(object sender, TEventArgs e);

public class BLEServerSubscriptionChangedEventArgs : AsyncEventArgs {
  public CancellationToken CancellationToken { get; }
  public string ServiceId { get; }
  public string CharacteristicId { get; }
  public bool IsSubscribed { get; }
}
                

Public Event OnSubscriptionChanged As OnSubscriptionChangedHandler

Public Delegate Sub OnSubscriptionChangedHandler(sender As Object, e As BLEServerSubscriptionChangedEventArgs)

Public Class BLEServerSubscriptionChangedEventArgs Inherits EventArgs
  Public ReadOnly Property ServiceId As String
  Public ReadOnly Property CharacteristicId As String
  Public ReadOnly Property IsSubscribed As Boolean
End Class

Async Version
Public Event OnSubscriptionChanged As AsyncEventHandler(Of BLEServerSubscriptionChangedEventArgs)

Public Delegate Function AsyncEventHandler(Of TEventArgs)(sender As Object, e As TEventArgs) As Task

Public Class BLEServerSubscriptionChangedEventArgs Inherits AsyncEventArgs
  Public ReadOnly Property CancellationToken As CancellationToken
  Public ReadOnly Property ServiceId As String
  Public ReadOnly Property CharacteristicId As String
  Public ReadOnly Property IsSubscribed As Boolean
End Class
                

Remarks

This event fires when a client subscribes to, or unsubscribes from, notifications or indications on a characteristic that was added (via AddCharacteristic) with the Notify or Indicate flag set.

ServiceId and CharacteristicId identify the characteristic. IsSubscribed reflects the characteristic's overall subscription state: True if it now has one or more subscribed clients, or False if it has none. This event does not indicate which specific client subscribed or unsubscribed, nor how many clients are currently subscribed.

To push a new value to any subscribed clients, use UpdateValue.

WriteRequested Event (BLEServer Component)

Fired when a client requests to write a characteristic's value.

Syntax

• C#
• VB.NET

public event OnWriteRequestedHandler OnWriteRequested;

public delegate void OnWriteRequestedHandler(object sender, BLEServerWriteRequestedEventArgs e);

public class BLEServerWriteRequestedEventArgs : EventArgs {
  public string ClientId { get; }
  public string ServiceId { get; }
  public string CharacteristicId { get; }
  public string Value { get; }
  public byte[] ValueB { get; }
  public bool WithResponse { get; }
  public bool Accept { get; set; }
}

Async Version
public event AsyncEventHandler<BLEServerWriteRequestedEventArgs> OnWriteRequested;

public delegate Task AsyncEventHandler<TEventArgs>(object sender, TEventArgs e);

public class BLEServerWriteRequestedEventArgs : AsyncEventArgs {
  public CancellationToken CancellationToken { get; }
  public string ClientId { get; }
  public string ServiceId { get; }
  public string CharacteristicId { get; }
  public string Value { get; }
  public byte[] ValueB { get; }
  public bool WithResponse { get; }
  public bool Accept { get; set; }
}
                

Public Event OnWriteRequested As OnWriteRequestedHandler

Public Delegate Sub OnWriteRequestedHandler(sender As Object, e As BLEServerWriteRequestedEventArgs)

Public Class BLEServerWriteRequestedEventArgs Inherits EventArgs
  Public ReadOnly Property ClientId As String
  Public ReadOnly Property ServiceId As String
  Public ReadOnly Property CharacteristicId As String
  Public ReadOnly Property Value As String
  Public ReadOnly Property ValueB As Byte()
  Public ReadOnly Property WithResponse As Boolean
  Public Property Accept As Boolean
End Class

Async Version
Public Event OnWriteRequested As AsyncEventHandler(Of BLEServerWriteRequestedEventArgs)

Public Delegate Function AsyncEventHandler(Of TEventArgs)(sender As Object, e As TEventArgs) As Task

Public Class BLEServerWriteRequestedEventArgs Inherits AsyncEventArgs
  Public ReadOnly Property CancellationToken As CancellationToken
  Public ReadOnly Property ClientId As String
  Public ReadOnly Property ServiceId As String
  Public ReadOnly Property CharacteristicId As String
  Public ReadOnly Property Value As String
  Public ReadOnly Property ValueB As Byte()
  Public ReadOnly Property WithResponse As Boolean
  Public Property Accept As Boolean
End Class
                

Remarks

This event fires when a connected client sends a request to write a new value to a characteristic that was added (via AddCharacteristic) with the Write or WriteWithoutResponse flag set.

ClientId identifies the requesting client, and ServiceId and CharacteristicId identify the characteristic being written to. Value holds the hex-encoded string of bytes the client wants to write. WithResponse is True if the client is expecting an acknowledgement (a "Write"), or False if it is not (a "Write Without Response").

If WithResponse is True, the response will use Accept to indicate if the request was accepted or rejected.

bleserver1.OnWriteRequested += (s, e) => { Console.WriteLine("Client " + e.ClientId + " wrote: " + e.Value); };

ServerCharacteristic Type

A GATT characteristic added to a BLE server.

Remarks

This type represents a GATT characteristic added to a BLE server.

• CanSubscribe
• Flags
• Id
• ServiceId
• Uuid

Fields

Constructors

• C#
• VB.NET

public ServerCharacteristic();
                

Public ServerCharacteristic()
                

ServerService Type

A GATT service added to a BLE server.

Remarks

This type represents a GATT service added to a BLE server.

• InstanceId
• Uuid

Fields

Constructors

• C#
• VB.NET

public ServerService();
                

Public ServerService()
                

Config Settings (BLEServer Component)

BLEServer Config Settings

Base Config Settings

Trappable Errors (BLEServer Component)

BLEServer Errors