.NET Core and Microsoft Bot Framework

1md bot
2cd bot
3dotnet new -t web

1    "Microsoft.AspNet.WebApi.Client": "5.2.3",
2    "System.Runtime.Serialization.Xml": "4.1.1",
3    "Microsoft.Extensions.Caching.Memory": "1.0.0",
4    "Microsoft.Extensions.Options.ConfigurationExtensions": "1.0.0",
5    "Microsoft.Extensions.DependencyInjection": "1.0.0",
6    "Microsoft.Extensions.DependencyInjection.Abstractions": "1.0.0"

1dotnet restore

1"BotCredentials": {
2    "ClientId": "{Replace with your ClientId}",
3    "ClientSecret": "{Replace with your ClientSecret}"
4  }

 1    // This method gets called by the runtime. Use this method to add services to the container.
 2    public void ConfigureServices(IServiceCollection services)
 3    {
 4        // Adding options so we can inject configurations.
 5        services.AddOptions();
 6
 7        // Register the bot credentials section
 8        services.Configure<BotCredentials>(Configuration.GetSection("BotCredentials"));
 9
10        // we'll be catching tokens, so enable MemoryCache.
11        services.AddMemoryCache();
12
13        services.AddMvc();
14     }

 1namespace WebApplication
 2{
 3    /// <summary>
 4    /// Bot Credentials
 5    /// </summary>
 6    public class BotCredentials
 7    {
 8        /// <summary>
 9        /// CLientId
10        /// </summary>
11        public string ClientId { get; set; }
12
13        /// <summary>
14        /// ClientSecret
15        /// </summary>
16        public string ClientSecret { get; set; }
17    }
18}

 1namespace WebApplication
 2{
 3    /// <summary>
 4    /// Token Response
 5    /// </summary>
 6    public class TokenResponse
 7    {
 8        /// <summary>
 9        /// Property to hold the token
10        /// </summary>
11        public string access_token { get; set; }
12    }
13}

  1namespace WebApplication.Controllers
  2{
  3    using System;
  4    using System.Collections.Generic;
  5    using System.Dynamic;
  6    using System.Net.Http;
  7    using System.Net.Http.Headers;
  8    using System.Threading.Tasks;
  9    using Microsoft.AspNetCore.Mvc;
 10    using Microsoft.Extensions.Caching.Memory;
 11    using Microsoft.Extensions.Options;
 12
 13    /// <summary>
 14    /// This controller will receive the skype messages and handle them to the EchoBot service. 
 15    /// </summary>
 16    [Route("api/[controller]")]
 17    public class MessagesController : Controller
 18    {
 19        /// <summary>
 20        /// memoryCache
 21        /// </summary>
 22        IMemoryCache memoryCache;
 23
 24        /// <summary>
 25        /// Bot Credentials
 26        /// </summary>
 27        BotCredentials botCredentials;
 28
 29        /// <summary>
 30        /// Constructor
 31        /// </summary>
 32        /// 
 33        /// 
 34        public MessagesController(IMemoryCache memoryCache, IOptions<BotCredentials> botCredentials)
 35        {
 36            this.memoryCache = memoryCache;
 37            this.botCredentials = botCredentials.Value;
 38        }
 39
 40        /// <summary>
 41        /// This method will be called every time the bot receives an activity. This is the messaging endpoint
 42        /// </summary>
 43        /// 
 44        /// <returns>201 Created</returns>
 45        [HttpPost]
 46        public virtual async Task<IActionResult> Post([FromBody] dynamic activity)
 47        {
 48            // Get the conversation id so the bot answers.
 49            var conversationId = activity.from.id.ToString();
 50
 51            // Get a valid token 
 52            string token = await this.GetBotApiToken();
 53
 54            // send the message back
 55            using (var client = new HttpClient())
 56            {
 57                // I'm using dynamic here to make the code simpler
 58                dynamic message = new ExpandoObject();
 59                message.type = "message/text";
 60                message.text = activity.text;
 61
 62                // Set the toekn in the authorization header.
 63                client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
 64
 65                // Post the message
 66                await client.PostAsJsonAsync<ExpandoObject>(
 67                    $"https://api.skype.net/v3/conversations/{conversationId}/activities",
 68                    message as ExpandoObject);
 69            }
 70
 71            return Created(Url.Content("~/"), string.Empty);
 72        }
 73
 74        /// <summary>
 75        /// Gets and caches a valid token so the bot can send messages.
 76        /// </summary>
 77        /// <returns>The token</returns>
 78        private async Task<string> GetBotApiToken()
 79        {
 80            // Check to see if we already have a valid token
 81            string token = memoryCache.Get("token")?.ToString();
 82            if (string.IsNullOrEmpty(token))
 83            {
 84                // we need to get a token.
 85                using (var client = new HttpClient())
 86                {
 87                    // Create the encoded content needed to get a token
 88                    var parameters = new Dictionary<string, string>
 89                    {
 90                        {"client_id", this.botCredentials.ClientId },
 91                        {"client_secret", this.botCredentials.ClientSecret },
 92                        {"scope", "https://graph.microsoft.com/.default" },
 93                        {"grant_type", "client_credentials" }
 94                    };
 95                    var content = new FormUrlEncodedContent(parameters);
 96
 97                    // Post
 98                    var response = await client.PostAsync("https://login.microsoftonline.com/common/oauth2/v2.0/token", content);
 99
100                    // Get the token response
101                    var tokenResponse = await response.Content.ReadAsAsync<TokenResponse>();
102
103                    token = tokenResponse.access_token;
104
105                    // Cache the token for 15 minutes.
106                    memoryCache.Set(
107                        "token",
108                        token,
109                        new DateTimeOffset(DateTime.Now.AddMinutes(15)));
110                }
111            }
112
113            return token;
114        }
115    }
116}