Add Basket handler and subscription to events. Change in EventBus to use broker and one message queue per microservice http://www.rabbitmq.com/tutorials/tutorial-four-dotnet.html

src/Services/Basket/Basket.API/Basket.API.csproj

@@ -39,6 +39,10 @@
     <PackageReference Include="Swashbuckle" Version="6.0.0-beta902" />
   </ItemGroup>
 
+  <ItemGroup>
+    <ProjectReference Include="..\..\Common\Infrastructure\Infrastructure.csproj" />
+  </ItemGroup>
+
   <ItemGroup>
     <None Update="Dockerfile">
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>

src/Services/Basket/Basket.API/Events/CatalogPriceChangedHandler.cs

@@ -0,0 +1,25 @@
+using Microsoft.eShopOnContainers.Services.Basket.API.Model;
+using Microsoft.eShopOnContainers.Services.Common.Infrastructure;
+using Microsoft.eShopOnContainers.Services.Common.Infrastructure.Catalog;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace Basket.API.Events
+{
+    public class CatalogPriceChangedHandler : IIntegrationEventHandler<CatalogPriceChanged>
+    {
+        private readonly IBasketRepository _repository;
+        public CatalogPriceChangedHandler()
+        {
+            //_repository = repository;
+        }
+
+        public void Handle(CatalogPriceChanged @event)
+        {
+            
+        }        
+    }
+}
+

src/Services/Basket/Basket.API/Startup.cs

@@ -13,6 +13,9 @@ using Microsoft.Extensions.Options;
 using System.Net;
 using Swashbuckle.Swagger.Model;
 using Microsoft.eShopOnContainers.Services.Basket.API.Auth.Server;
+using Microsoft.eShopOnContainers.Services.Common.Infrastructure;
+using Microsoft.eShopOnContainers.Services.Common.Infrastructure.Catalog;
+using Basket.API.Events;
 
 namespace Microsoft.eShopOnContainers.Services.Basket.API
 {
@@ -76,6 +79,9 @@ namespace Microsoft.eShopOnContainers.Services.Basket.API
             });
 
             services.AddTransient<IBasketRepository, RedisBasketRepository>();
+            var eventBus = new EventBus();            
+            services.AddSingleton<IEventBus>(eventBus);
+            eventBus.Subscribe<CatalogPriceChanged>(new CatalogPriceChangedHandler());            
         }
 
         // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.

src/Services/Catalog/Catalog.API/Controllers/CatalogController.cs

@@ -107,7 +107,7 @@ namespace Microsoft.eShopOnContainers.Services.Catalog.API.Controllers
             //hook to run integration tests until POST methods are created
             if (catalogTypeId.HasValue && catalogTypeId == 1)
             {
-                _eventBus.Publish(new CatalogPriceChanged());
+                _eventBus.Publish(new CatalogPriceChanged(2, 10.4M));
             }
 
             return Ok(model);

src/Services/Common/Infrastructure/Catalog/CatalogPriceChanged.cs

@@ -6,15 +6,16 @@ namespace Microsoft.eShopOnContainers.Services.Common.Infrastructure.Catalog
 {
     public class CatalogPriceChanged : IIntegrationEvent
     {
-        private readonly string _eventName = "catalogpricechanged";
+        public string Message { get { return "CatalogPriceChanged here!!"; } }
 
-        public string Name {
-            get
-            {
-                return _eventName;
-            }
-        }
+        public int ItemId { get; private set; }
+
+        public decimal NewPrice { get; private set; }
 
-        public string Message { get { return "CatalogPriceChanged!!"; } }
-    }
+        public CatalogPriceChanged(int itemId, decimal newPrice)
+        {
+            ItemId = itemId;
+            NewPrice = newPrice;
+        }
+}
 }

src/Services/Common/Infrastructure/Catalog/CatalogPriceChangedHandler.cs

@@ -1,14 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Text;
-
-namespace Microsoft.eShopOnContainers.Services.Common.Infrastructure.Catalog
-{
-    public class CatalogPriceChangedHandler : IIntegrationEventHandler<CatalogPriceChanged>
-    {
-        public void Handle(CatalogPriceChanged @event)
-        {
-            throw new NotImplementedException();
-        }
-    }
-}

src/Services/Common/Infrastructure/EventBus.cs

@@ -1,40 +1,47 @@
 
 using Microsoft.eShopOnContainers.Services.Common.Infrastructure.Catalog;
+using Newtonsoft.Json;
 using RabbitMQ.Client;
 using RabbitMQ.Client.Events;
 using System;
+using System.Collections;
 using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
 using System.Text;
 
 namespace Microsoft.eShopOnContainers.Services.Common.Infrastructure
 {
     public class EventBus : IEventBus
     {
-        private readonly Dictionary<string, List<IIntegrationEventHandler>>  _handlers;        
-        private readonly Dictionary<string, Tuple<IModel, IConnection>> _listeners;
+        private readonly string _brokerName = "event_bus";
+        private readonly Dictionary<string, List<IIntegrationEventHandler>>  _handlers;
+        private readonly List<Type> _eventTypes;
+
+        private Tuple<IModel, IConnection> _connection;
+        private string _queueName;
+        
 
         public EventBus()
         {
             _handlers = new Dictionary<string, List<IIntegrationEventHandler>>();
-            _listeners = new Dictionary<string, Tuple<IModel, IConnection>>();
+            _eventTypes = new List<Type>();
         }
         public void Publish(IIntegrationEvent @event)
         {
+            var eventName = @event.GetType().Name;
             var factory = new ConnectionFactory() { HostName = "172.20.0.1" };
             using (var connection = factory.CreateConnection())
             using (var channel = connection.CreateModel())
-            {                
-                channel.QueueDeclare(queue: @event.Name,
-                                     durable: false,
-                                     exclusive: false,
-                                     autoDelete: false,
-                                     arguments: null);
+            {
+                channel.ExchangeDeclare(exchange: _brokerName,
+                                    type: "direct");
 
-                string message = ((CatalogPriceChanged)@event).Message;                
+                string message = JsonConvert.SerializeObject(@event);                                
                 var body = Encoding.UTF8.GetBytes(message);
 
-                channel.BasicPublish(exchange: "",
-                                     routingKey: @event.Name,
+                channel.BasicPublish(exchange: _brokerName,
+                                     routingKey: eventName,
                                      basicProperties: null,
                                      body: body);                
             }
@@ -50,30 +57,14 @@ namespace Microsoft.eShopOnContainers.Services.Common.Infrastructure
             }
             else
             {
-                var factory = new ConnectionFactory() { HostName = "172.18.0.1" };
-                var connection = factory.CreateConnection();
-                var channel = connection.CreateModel();
-                
-                channel.QueueDeclare(queue: eventName,
-                                     durable: false,
-                                     exclusive: false,
-                                     autoDelete: false,
-                                     arguments: null);
-
-                var consumer = new EventingBasicConsumer(channel);
-                consumer.Received += (model, ea) =>
-                {
-                    var body = ea.Body;
-                    var message = Encoding.UTF8.GetString(body);                    
-                };
-                channel.BasicConsume(queue: "hello",
-                                     noAck: true,
-                                     consumer: consumer);
-                ;
-
-                _listeners.Add(eventName, new Tuple<IModel, IConnection>(channel, connection));
+                var channel = GetChannel();
+                channel.QueueBind(queue: _queueName,
+                                  exchange: _brokerName,
+                                  routingKey: eventName);
+                                               
                 _handlers.Add(eventName, new List<IIntegrationEventHandler>());
                 _handlers[eventName].Add(handler);
+                _eventTypes.Add(typeof(T));
             }
             
         }
@@ -88,13 +79,69 @@ namespace Microsoft.eShopOnContainers.Services.Common.Infrastructure
                 if (_handlers[eventName].Count == 0)
                 {
                     _handlers.Remove(eventName);
+                    var eventType = _eventTypes.Single(e => e.Name == eventName);
+                    _eventTypes.Remove(eventType);
+                    _connection.Item1.QueueUnbind(queue: _queueName, 
+                        exchange: _brokerName, 
+                        routingKey: eventName);
+
+                    if (_handlers.Keys.Count == 0)
+                    {
+                        _queueName = string.Empty;
+                        _connection.Item1.Close();
+                        _connection.Item2.Close();
+                    }
+                    
+                }
+            }
+        }
 
-                    var connectionItems =_listeners[eventName];
-                    _listeners.Remove(eventName);
+        private IModel GetChannel()
+        {
+            if (_connection != null)
+            {
+                return _connection.Item1;
+            }
+            else
+            {
+                var factory = new ConnectionFactory() { HostName = "172.20.0.1" };
+                var connection = factory.CreateConnection();
+                var channel = connection.CreateModel();
 
-                    connectionItems.Item1.Close();
-                    connectionItems.Item2.Close();
+                channel.ExchangeDeclare(exchange: _brokerName,
+                                    type: "direct");
+                if (string.IsNullOrEmpty(_queueName))
+                {
+                    _queueName = channel.QueueDeclare().QueueName;
                 }
+
+                var consumer = new EventingBasicConsumer(channel);
+                consumer.Received += (model, ea) =>
+                {                    
+                    var eventName = ea.RoutingKey;
+                    if (_handlers.ContainsKey(eventName))
+                    {                        
+                        var message = Encoding.UTF8.GetString(ea.Body);
+                        Type eventType = _eventTypes.Single(t => t.Name == eventName);
+                        
+                        var integrationEvent = JsonConvert.DeserializeObject(message, eventType);                        
+                        var handlers = _handlers[eventName];
+
+                                             
+                        var concreteType = typeof(IIntegrationEventHandler<>).MakeGenericType(eventType);
+                        
+                        foreach (var handler in handlers)
+                        {
+                            concreteType.GetMethod("Handle").Invoke(handler, new object[] { integrationEvent });
+                        }
+                    }
+                };
+                channel.BasicConsume(queue: _queueName,
+                                     noAck: true,
+                                     consumer: consumer);
+                _connection = new Tuple<IModel, IConnection>(channel, connection);
+
+                return _connection.Item1;
             }
         }
     }

src/Services/Common/Infrastructure/IIntegrationEvent.cs

@@ -5,7 +5,6 @@ using System.Text;
 namespace Microsoft.eShopOnContainers.Services.Common.Infrastructure
 {
     public interface IIntegrationEvent
-    {
-        string Name { get; }
+    {        
     }
 }

src/Services/Common/Infrastructure/IIntegrationEventHandler.cs

@@ -10,5 +10,7 @@ namespace Microsoft.eShopOnContainers.Services.Common.Infrastructure
         void Handle(TIntegrationEvent @event);
     }
 
-    public interface IIntegrationEventHandler { }
+    public interface IIntegrationEventHandler
+    {
+    }
 }

src/Services/Common/Infrastructure/Infrastructure.csproj

@@ -5,6 +5,7 @@
     <RootNamespace>Microsoft.eShopOnContainers.Services.Common.Infrastructure</RootNamespace>    
   </PropertyGroup>
   <ItemGroup>
+    <PackageReference Include="Newtonsoft.Json" Version="9.0.1" />
     <PackageReference Include="RabbitMQ.Client" Version="4.1.1" />
   </ItemGroup>
 </Project>