gistfile1.txt

using System;
using System.Net;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;
using System.Web.Http;
using StackExchange.Redis;


namespace WebApplication2.Controllers
{
    public class Controller1Controller : ApiController
    {
        readonly ConnectionMultiplexer redis = ConnectionMultiplexer.Connect("localhost");

        [HttpGet]
        public async Task<HttpResponseMessage> Login(string loginName)
        {

            var result = await GoToRedis(loginName); //pause the request until an appropriate response 
            return Request.CreateResponse(HttpStatusCode.OK, result); ;
        }


        public async Task<Task<bool>> GoToRedis(string loginName) //redis connects the  LOGIN interface AND a far distance server 
                                                                  //which actually *has the knowledge* to check if login is valid or not.
        {

            var tcs = new TaskCompletionSource<bool>();

            ISubscriber sub = redis.GetSubscriber();
            await sub.SubscribeAsync("channel", (channel, message) =>
           {
               //wait for far server publish
               if (message == loginName + "OK") 
                    tcs.SetResult(true);
           });

            return tcs.Task;
        }
    }
}