Examples for simple owin authentication

Owin.Authentication.Examples.cs

# Your use statement can do all the work for you

app.Use(async (context, next) =>
{
  if (!IsAuthenticated(context))
  {
    context.Response.StatusCode = 401;
    var bytes = System.Text.Encoding.UTF8.GetBytes("You are not authorised!");
    context.Response.Body.Write(bytes, 0, bytes.Length);
    await Task.FromResult(context);
  }
  else
  {
    await next();
  }
});

# Or authorization on each get
app.MapWhen(whenContext => {
    return IsAuthenticated && whenContext.Request.Method == "GET" && whenContext.Request.Uri.IsMatch("/helloworld")
  }, env => {
    env.Use(async (context, next) =>
    {
      var bytes = System.Text.Encoding.UTF8.GetBytes("Hello world! This will return a 200 status code by default.");
      context.Response.Body.Write(bytes, 0, bytes.Length);
      await next();
    });
  });