/// <summary>
/// Start hosted command handler.
/// </summary>
/// <param name="cancellationToken">Cancellation token.</param>
/// <returns>Completed asynchronous task.</returns>
public virtual Task Start(CancellationToken cancellationToken = default(CancellationToken))
{
// Get an instance provided by child class and store in a private property.
_internalCommandSource = CommandSource;
if (_internalCommandSource == null)
{
throw new InvalidOperationException("Hosted command handler has no command source.");
}
OnStart();
// Subscribe.
_internalCommandSource.CommandReceived += (receivedCommand, ct) =>
{
TCommand command = receivedCommand as TCommand;
if (command != null)
{
ProcessCommandAsync(command, cancellationToken);
}
return(TaskUtility.CompletedTask);
};
_internalCommandSource.StartReceiving(cancellationToken);
return(TaskUtility.CompletedTask);
}