简单易用的.NET免费开源RabbitMQ操作组件EasyNetQ解析
对于目前大多的.NET项目，其实使用的技术栈都是差不多，估计现在很少用控件开发项目的了，毕竟一大堆问题。对.NET的项目，目前比较适合的架构ASP.NET MVC，ASP.NET WebAPI，ORM（较多Dapper.NET或者其扩展，稍大一些的项目用EF等等），为了提高速度也会采用缓存（.NET自带的Memcache，或者Redis），请求较多的项目，使用Nginx做负载均衡和使用队列等等。
上面简单的介绍一下.NET的项目的技术架构，具体的技术根据具体的需求做出选择。介绍到队列，很多人都会很熟悉，例如MSMQ，RabbitMQ等等队列。既然需要使用队列，那就要考虑如何使用C#更好的操作队列。
一.RabbitMQ概述
在现在的项目中，消息队列的使用比较的频繁，消息队列的种类也较多，如：ActiveMQ，RabbitMQ，ZeroMQ，Kafka，MetaMQ，RocketMQ等。消息队列中间件是分布式系统中重要的组件，主要解决应用耦合，异步消息，流量削锋等问题。实现高性能，高可用，可伸缩和最终一致性架构。是大型分布式系统不可缺少的中间件。
在这里主要介绍RabbitMQ消息队列，支持开放的高级消息队列协议 (AMQP)。RabbitMQ的特点：强大的应用程序消息传递；使用方便；运行在所有主要操作系统上；支持大量开发人员平台；开源和商业支持。消息队列的模式有两种模式：P2P（Point to Point），P2P模式包含三个角色：消息队列（Queue），发送者(Sender)，接收者(Receiver)。每个消息都被发送到一个特定的队列，接收者从队列中获取消息。队列保留着消息，直到他们被消费或超时。Publish/Subscribe(Pub/Sub)，包含三个角色主题（Topic），发布者（Publisher），订阅者（Subscriber） 。多个发布者将消息发送到Topic,系统将这些消息传递给多个订阅者。
上面介绍了RabbitMQ的相关特点和模式，更多的知识就不再介绍，需要了解安装和配置，可以进入官网进行细致的了解。
二.EasyNetQ组件概述
上面介绍了RabbitMQ的应用场景和使用的模式，在.NET的项目开发中，较多的使用MSMQ作为消息队列，很多人对于MSMQ的操作比较熟悉，也属于轻量级的消息队列。对于RabbitMQ是较为重量级的消息队列，有多个语言的版本，作为.NET开发者对于RabbitMQ的操作可能就比较少。在.NET项目中如何更方便的使用RabbitMQ，在这里就介绍一个.NET操作RabbitMQ的组件EasyNetQ。
EasyNetQ的目标是提供一个使.NET中的RabbitMQ尽可能简单的库。在EasyNetQ中消息应由.NET类型表示，消息应通过其.NET类型进行路由。EasyNetQ按消息类型进行路由。发布消息时，EasyNetQ会检查其类型，并根据类型名称，命名空间和装配体给出一个路由密钥。在消费方面，用户订阅类型。订阅类型后，该类型的消息将路由到订户。默认情况下，EasyNetQ使用Newtonsoft.Json库将.NET类型序列化为JSON。这具有消息是人类可读的优点，因此您可以使用RabbitMQ管理应用程序等工具来调试消息问题。
EasyNetQ是在RabbitMQ.Client库之上提供服务的组件集合。这些操作可以像序列化，错误处理，线程编组，连接管理等。它们由mini-IoC容器组成。您可以轻松地用自己的实现替换任何组件。因此，如果您希望XML序列化而不是内置的JSON，只需编写一个ISerializer的实现并将其注册到容器。
以下是官方提供的一个结构图，这个结构图可以很好的解析该组件的结构：
三.EasyNetQ组件使用方式
介绍完毕EasyNetQ组件的相关背景，现在就要介绍一下该组件的使用方式。EasyNetQ组件的使用方式比较简单，跟很多组件都类似，例如：建立连接，进行操作做等等，对于EasyNetQ组件也是如此。
1.创建连接：
var bus = RabbitHutch.CreateBus(“host=myServer;virtualHost=myVirtualHost;username=mike;password=topsecret”);
与RabbitMQ服务器的延迟连接由IBus接口表示，创建连接的方式连接字符串由格式为key = value的键/值对组成，每一个用分号（;）分隔。host：主机地址；virtualHost：默认是默认的虚拟主机’/’；username：用户名，默认为’guest’；password：密码，默认是’guest’；
2.关闭连接：
bus.Dispose();
要关闭连接，只需简单地处理总线，这将关闭EasyNetQ使用的连接，渠道，消费者和所有其他资源。
3.发布消息：
var message = new MyMessage { Text = "Hello Rabbit" };
bus.Publish(message);
4.订阅邮件：
bus.Subscribe<MyMessage>("my_subscription_id", msg => Console.WriteLine(msg.Text));
5.远程过程调用：
var request = new TestRequestMessage {Text = "Hello from the client! "};
bus.Request<TestRequestMessage, TestResponseMessage>(request, response => Console.WriteLine("Got response: '{0}'",response.Text));
6.RPC服务器：
bus.Respond<TestRequestMessage, TestResponseMessage>(request => new TestResponseMessage{ Text = request.Text + " all done!" });
7.记录器：
var logger = new MyLogger() ;
var bus = RabbitHutch.CreateBus(“my connection string”, x => x.Register<IEasyNetQLogger>(_ => logger));
8.路由：
bus.Subscribe("my_id", handler, x => x.WithTopic("X.*"));
RabbitMQ具有非常好的功能，基于主题的路由，允许订阅者基于多个标准过滤消息。*（星号）匹配一个字。＃（哈希）匹配为零个或多个单词。
四.EasyNetQ组件核心对象解析
上面简单的介绍了一下该组件的应用方式，还有比较多的方式没有做介绍，又需要的可以做深入的了解。在这里介绍一下该组件的一些核心的对象。
1.RabbitHutch.CreateBus()：
旧版方法
public static IBus CreateBus(ConnectionConfiguration connectionConfiguration, AdvancedBusEventHandlers advancedBusEventHandlers,
Action<IServiceRegister> registerServices)
{
Preconditions.CheckNotNull(connectionConfiguration, "connectionConfiguration");
Preconditions.CheckNotNull(advancedBusEventHandlers, "advancedBusEventHandlers");
Preconditions.CheckNotNull(registerServices, "registerServices");
var container = createContainerInternal();
if (container == null)
{
throw new EasyNetQException("Could not create container. " +
"Have you called SetContainerFactory(...) with a function that returns null?");
}
connectionConfiguration.Validate();
container.Register(_ => connectionConfiguration);
container.Register(_ => advancedBusEventHandlers);
registerServices(container);
ComponentRegistration.RegisterServices(container);
return container.Resolve<IBus>();
}
在RabbitHutch类中主要包含的方法是CreateBus()方法，具有12个重载。该方法主要根据用户的连接配置信息，连接服务端。该方法接收三个参数，connectionConfiguration表示连接实例，advancedBusEventHandlers用于添加处理程序的AdvancedBusEventHandlers实例到新创建的IBus.Advanced”的事件。registerServices覆盖默认服务。 ComponentRegistration.RegisterServices(container);在我们内部的超简单IoC容器中注册默认的EasyNetQ组件。container.Resolve获取所请求的服务的实例。 注意所有服务都是单例的，多次通话Resolve将返回相同的实例。
EasyNetQ 3.3.4 新版
RabbitHutch.cs
using System;
using System.Collections.Generic;
#if NETFX
using System.Configuration;
#endif
using EasyNetQ.ConnectionString;
using EasyNetQ.DI;
namespace EasyNetQ
{
/// section" +
"of the application's configuration file. For example: " +
"IBus接口
using System;
using EasyNetQ.Producer;
using EasyNetQ.Scheduling;
namespace EasyNetQ
{
/// 2.IBus.Publish()：
旧版本的方法
public virtual void Publish<T>(T message, Action<IPublishConfiguration> configure) where T : class
{
Preconditions.CheckNotNull(message, "message");
Preconditions.CheckNotNull(configure, "configure");
var configuration = new PublishConfiguration(conventions.TopicNamingConvention(typeof(T)));
configure(configuration);
var messageType = typeof(T);
var easyNetQMessage = new Message<T>(message)
{
Properties =
{
DeliveryMode = messageDeliveryModeStrategy.GetDeliveryMode(messageType)
}
};
if (configuration.Priority != null)
easyNetQMessage.Properties.Priority = configuration.Priority.Value;
if (configuration.Expires != null)
easyNetQMessage.Properties.Expiration = configuration.Expires.ToString();
var exchange = publishExchangeDeclareStrategy.DeclareExchange(advancedBus, messageType, ExchangeType.Topic);
advancedBus.Publish(exchange, configuration.Topic, false, easyNetQMessage);
}
该方法用于发布消息，该方法是一个虚方法，在子类中可以被重写。 var configuration = new PublishConfiguration(conventions.TopicNamingConvention(typeof(T)))用于定义发布信息的配置，Message定义邮件正文内容。
EasyNetQ 3.3.4 新版
PubSubExtensions扩展类
using System;
using System.Threading;
using System.Threading.Tasks;
using EasyNetQ.FluentConfiguration;
using EasyNetQ.Internals;
namespace EasyNetQ.Producer
{
public static class PubSubExtensions
{
/// The message type
/// The pubSub instance
/// /// The message to publish
/// The cancellation token
/// The message type
/// The pubSub instance
/// /// The message to publish
/// The topic string
/// The cancellation token
/// The message type
/// The pubSub instance
/// The message to publish
/// The cancellation token
public static void Publish<T>(this IPubSub pubSub, T message, CancellationToken cancellationToken = default)
{
Preconditions.CheckNotNull(pubSub, "pubSub");
pubSub.Publish(message, c => { }, cancellationToken);
}
/// The message type
/// The pubSub instance
/// The message to publish
///
/// Fluent configuration e.g. x => x.WithTopic("*.brighton").WithPriority(2)
///
/// The cancellation token
public static void Publish<T>(this IPubSub pubSub, T message, Action<IPublishConfiguration> configure, CancellationToken cancellationToken = default)
{
Preconditions.CheckNotNull(pubSub, "pubSub");
pubSub.PublishAsync(message, configure, cancellationToken)
.GetAwaiter()
.GetResult();
}
/// The message type
/// The pubSub instance
/// The message to publish
/// The topic string
/// The cancellation token
public static void Publish<T>(this IPubSub pubSub, T message, string topic, CancellationToken cancellationToken = default)
{
Preconditions.CheckNotNull(pubSub, "pubSub");
pubSub.Publish(message, c => c.WithTopic(topic), cancellationToken);
}
/// The type to subscribe to
/// The pubSub instance
///
/// A unique identifier for the subscription. Two subscriptions with the same subscriptionId
/// and type will get messages delivered in turn. This is useful if you want multiple subscribers
/// to load balance a subscription in a round-robin fashion.
///
///
/// The action to run when a message arrives. When onMessage completes the message
/// receipt is Ack'd. All onMessage delegates are processed on a single thread so you should
/// avoid long running blocking IO operations. Consider using SubscribeAsync
///
/// The cancellation token
/// The type to subscribe to
/// The pubSub instance
///
/// A unique identifier for the subscription. Two subscriptions with the same subscriptionId
/// and type will get messages delivered in turn. This is useful if you want multiple subscribers
/// to load balance a subscription in a round-robin fashion.
///
///
/// The action to run when a message arrives. When onMessage completes the message
/// receipt is Ack'd. All onMessage delegates are processed on a single thread so you should
/// avoid long running blocking IO operations. Consider using SubscribeAsync
///
///
/// Fluent configuration e.g. x => x.WithTopic("uk.london")
///
/// The cancellation token
/// The type to subscribe to
/// The pubSub instance
///
/// A unique identifier for the subscription. Two subscriptions with the same subscriptionId
/// and type will get messages delivered in turn. This is useful if you want multiple subscribers
/// to load balance a subscription in a round-robin fashion.
///
///
/// The action to run when a message arrives. onMessage can immediately return a Task and
/// then continue processing asynchronously. When the Task completes the message will be
/// Ack'd.
///
/// The cancellation token
/// The type to subscribe to
/// The pubSub instance
///
/// A unique identifier for the subscription. Two subscriptions with the same subscriptionId
/// and type will get messages delivered in turn. This is useful if you want multiple subscribers
/// to load balance a subscription in a round-robin fashion.
///
///
/// The action to run when a message arrives. When onMessage completes the message
/// receipt is Ack'd. All onMessage delegates are processed on a single thread so you should
/// avoid long running blocking IO operations. Consider using SubscribeAsync
///
/// The cancellation token
/// The type to subscribe to
/// The pubSub instance
///
/// A unique identifier for the subscription. Two subscriptions with the same subscriptionId
/// and type will get messages delivered in turn. This is useful if you want multiple subscribers
/// to load balance a subscription in a round-robin fashion.
///
///
/// The action to run when a message arrives. When onMessage completes the message
/// receipt is Ack'd. All onMessage delegates are processed on a single thread so you should
/// avoid long running blocking IO operations. Consider using SubscribeAsync
///
///
/// Fluent configuration e.g. x => x.WithTopic("uk.london")
///
/// The cancellation token
/// The type to subscribe to
/// The pubSub instance
///
/// A unique identifier for the subscription. Two subscriptions with the same subscriptionId
/// and type will get messages delivered in turn. This is useful if you want multiple subscribers
/// to load balance a subscription in a round-robin fashion.
///
///
/// The action to run when a message arrives. onMessage can immediately return a Task and
/// then continue processing asynchronously. When the Task completes the message will be
/// Ack'd.
///
/// The cancellation token
/// The type to subscribe to
/// The pubSub instance
///
/// A unique identifier for the subscription. Two subscriptions with the same subscriptionId
/// and type will get messages delivered in turn. This is useful if you want multiple subscribers
/// to load balance a subscription in a round-robin fashion.
///
///
/// The action to run when a message arrives. onMessage can immediately return a Task and
/// then continue processing asynchronously. When the Task completes the message will be
/// Ack'd.
///
///
/// Fluent configuration e.g. x => x.WithTopic("uk.london")
///
/// The cancellation token
/// 五.总结
以上是对该组件的简单的介绍，如果需要了解更多的内容可以自己去深入的学习和研究。知识在于自己的勤奋，他人只是一个简单的引导。