Program.cs

using System;
using System.Collections.Concurrent;
using System.Net;
using System.Net.Sockets;
using System.Text;
using NetCoreServer;

namespace HttpServer
{
  class CommonCache
  {
    public static CommonCache GetInstance()
    {
      if (_instance == null)
        _instance = new CommonCache();
      return _instance;
    }

    public string GetAllCache()
    {
      var result = new StringBuilder();
      result.Append("[\n");
      foreach (var item in _cache)
      {
        result.Append("  {\n");
        result.AppendFormat($"    \"key\": \"{item.Key}\",\n");
        result.AppendFormat($"    \"value\": \"{item.Value}\",\n");
        result.Append("  },\n");
      }
      result.Append("]\n");
      return result.ToString();
    }

    public bool GetCacheValue(string key, out string value)
    {
      return _cache.TryGetValue(key, out value);
    }

    public void PutCacheValue(string key, string value)
    {
      _cache[key] = value;
    }

    public bool DeleteCacheValue(string key, out string value)
    {
      return _cache.TryRemove(key, out value);
    }

    private readonly ConcurrentDictionary<string, string> _cache = new ConcurrentDictionary<string, string>();
    private static CommonCache _instance;
  }

  class HttpCacheSession : HttpSession
  {
    public HttpCacheSession(NetCoreServer.HttpServer server) : base(server) { }

    protected override void OnReceivedRequest(HttpRequest request)
    {
      // Show HTTP request content
      Console.WriteLine(request);

      // Process HTTP request methods
      if (request.Method == "HEAD")
        SendResponseAsync(Response.MakeHeadResponse());
      else if (request.Method == "GET")
      {
        string key = request.Url;

        // Decode the key value
        key = Uri.UnescapeDataString(key);
        key = key.Replace("/api/cache", "", StringComparison.InvariantCultureIgnoreCase);
        key = key.Replace("?key=", "", StringComparison.InvariantCultureIgnoreCase);

        if (string.IsNullOrEmpty(key))
        {
          // Response with all cache values
          SendResponseAsync(Response.MakeGetResponse(CommonCache.GetInstance().GetAllCache(), "application/json; charset=UTF-8"));
        }
        // Get the cache value by the given key
        else if (CommonCache.GetInstance().GetCacheValue(key, out var value))
        {
          // Response with the cache value
          SendResponseAsync(Response.MakeGetResponse(value));
        }
        else
          SendResponseAsync(Response.MakeErrorResponse(404, "Required cache value was not found for the key: " + key));
      }
      else if ((request.Method == "POST") || (request.Method == "PUT"))
      {
        string key = request.Url;
        string value = request.Body;

        // Decode the key value
        key = Uri.UnescapeDataString(key);
        key = key.Replace("/api/cache", "", StringComparison.InvariantCultureIgnoreCase);
        key = key.Replace("?key=", "", StringComparison.InvariantCultureIgnoreCase);

        // Put the cache value
        CommonCache.GetInstance().PutCacheValue(key, value);

        // Response with the cache value
        SendResponseAsync(Response.MakeOkResponse());
      }
      else if (request.Method == "DELETE")
      {
        string key = request.Url;

        // Decode the key value
        key = Uri.UnescapeDataString(key);
        key = key.Replace("/api/cache", "", StringComparison.InvariantCultureIgnoreCase);
        key = key.Replace("?key=", "", StringComparison.InvariantCultureIgnoreCase);

        // Delete the cache value
        if (CommonCache.GetInstance().DeleteCacheValue(key, out var value))
        {
          // Response with the cache value
          SendResponseAsync(Response.MakeGetResponse(value));
        }
        else
          SendResponseAsync(Response.MakeErrorResponse(404, "Deleted cache value was not found for the key: " + key));
      }
      else if (request.Method == "OPTIONS")
        SendResponseAsync(Response.MakeOptionsResponse());
      else if (request.Method == "TRACE")
        SendResponseAsync(Response.MakeTraceResponse(request));
      else
        SendResponseAsync(Response.MakeErrorResponse("Unsupported HTTP method: " + request.Method));
    }

    protected override void OnReceivedRequestError(HttpRequest request, string error)
    {
      Console.WriteLine($"Request error: {error}");
    }

    protected override void OnError(SocketError error)
    {
      Console.WriteLine($"HTTP session caught an error: {error}");
    }
  }

  class HttpCacheServer : NetCoreServer.HttpServer
  {
    public HttpCacheServer(IPAddress address, int port) : base(address, port) { }

    public HttpCacheServer(UnixDomainSocketEndPoint endpoint) : base(endpoint) { }

    protected override TcpSession CreateSession() { return new HttpCacheSession(this); }

    protected override void OnError(SocketError error)
    {
      Console.WriteLine($"HTTP session caught an error: {error}");
    }
  }

  class Program
  {
    static void Main(string[] args)
    {
      // HTTP server port
      var unixSocketPath = "/tmp/test.sock";
      // HTTP server content path
      string www = "../../../../../www/api";
      if (args.Length > 1)
        www = args[1];

      Console.WriteLine($"HTTP server socket path: {unixSocketPath}");
      Console.WriteLine($"HTTP server static content path: {www}");
      Console.WriteLine($"HTTP server test with  curl --unix-socket {unixSocketPath} http://localhost/api/index.html");
      Console.WriteLine($"You may also setup run nginx -c $PWD/NetCoreServer.conf to test the server with a browser (make sure all paths in the conf file exists)");

      Console.WriteLine();

      // Create a new HTTP server
      var server = new HttpCacheServer(new UnixDomainSocketEndPoint(unixSocketPath));
      server.AddStaticContent(www, "/api");

      // Start the server
      Console.Write("Server starting...");
      server.Start();
      Console.WriteLine("Done!");

      Console.WriteLine("Press Enter to stop the server or '!' to restart the server...");

      // Perform text input
      for (; ; )
      {
        string line = Console.ReadLine();
        if (string.IsNullOrEmpty(line))
          break;

        // Restart the server
        if (line == "!")
        {
          Console.Write("Server restarting...");
          server.Restart();
          Console.WriteLine("Done!");
        }
      }

      // Stop the server
      Console.Write("Server stopping...");
      server.Stop();
      Console.WriteLine("Done!");
    }
  }
}