var sockJs = new SockJS("http://localhost:9999/echo");
sockJs.Connected += async (sender, e) =>
{
    // this event is triggered once the connection is established
    try
    {
        Console.WriteLine("Connected...");
        await sockJs.Send(JsonConvert.SerializeObject(new { foo = "bar" }));
    }
    catch (Exception ex)
    {
        Console.WriteLine($"Error: {e}");
    }
};

sockJs.Message += async (sender, msg) =>
{
    // this event is triggered every time a message is received
    try
    {
        Console.WriteLine($"Message: {msg}");
        await sockJs.Disconnect(); // disconnect after first received message
    }
    catch (Exception ex)
    {
        Console.WriteLine($"Error: {e}");
    }
};

sockJs.Disconnected += (sender, e) =>
{
    // this event is triggered when the connection is disconnected (for any reason)
    Console.WriteLine("Disconnected");
};

await sockJs.Connect(); // connect to the server

// create a default configuration file (default values)
var config = Configuration.Factory.BuildDefault("http://localhost:9999/echo"); 
var sockJs = new SockJs(config);

config.Logger = new ConsoleLogger();

config.DefaultHeaders = new WebHeaderCollection
{
    {HttpRequestHeader.UserAgent, "Custom User Agent"},
    {"application-key", "foo-bar"}
};

// add custom transport implementations
config.TransportFactories.Add(new CustomTransportFactory());

// remove custom/built-in transport implementation
config.TransportFactories.Remove(config.TransportFactories.First(t => t.Name == "websocket-system"));

// disable transport
config.TransportFactories.First(t => t.Name == "websocket-system").Enabled = false;