Azure Event Hub 技术研究系列3-Event Hub接收事件

上篇博文中，我们通过编程的方式介绍了如何将事件消息发送到Azure Event Hub：

Azure Event Hub 技术研究系列2-发送事件到Event Hub

本篇文章中，我们继续：从Event Hub中接收事件。

1. 新建控制台工程 EventHubReceiver

2. 添加Nuget引用

Microsoft.Azure.EventHubs

Microsoft.Azure.EventHubs.Processor

3. 实现IEventProcessor接口

MyEventProcessor

    using Microsoft.Azure.EventHubs;
    using Microsoft.Azure.EventHubs.Processor;
    using System.Threading.Tasks;

    public class MyEventProcessor : IEventProcessor
    {
        public Task CloseAsync(PartitionContext context, CloseReason reason)
        {
            Console.WriteLine($"Processor Shutting Down. Partition '{context.PartitionId}', Reason: '{reason}'.");
            return Task.CompletedTask;
        }

        public Task OpenAsync(PartitionContext context)
        {
            Console.WriteLine($"MyEventProcessor initialized. Partition: '{context.PartitionId}'");
            return Task.CompletedTask;
        }

        public Task ProcessErrorAsync(PartitionContext context, Exception error)
        {
            Console.WriteLine($"Error on Partition: {context.PartitionId}, Error: {error.Message}");
            return Task.CompletedTask;
        }

        public Task ProcessEventsAsync(PartitionContext context, IEnumerable<EventData> messages)
        {
            foreach (var eventData in messages)
            {
                var data = Encoding.UTF8.GetString(eventData.Body.Array, eventData.Body.Offset, eventData.Body.Count);
                Console.WriteLine($"Event message received. Partition: '{context.PartitionId}', Data: '{data}'");
            }

            return context.CheckpointAsync();
        }
    }

4. Program程序

添加常量作为事件中心连接字符串、事件中心名称、存储帐户容器名称、存储帐户名称和存储帐户密钥。 添加以下代码，并将占位符替换为其对应的值。

        private const string EhConnectionString = "{Event Hubs connection string}";
        private const string EhEntityPath = "{Event Hub path/name}"; //MyEventHub
        private const string StorageContainerName = "{Storage account container name}"; //eventhubcontainer
        private const string StorageAccountName = "{Storage account name}"; //linux1
        private const string StorageAccountKey = "{Storage account key}";
        private static readonly string StorageConnectionString = string.Format("DefaultEndpointsProtocol=https;AccountName={0};AccountKey={1}", StorageAccountName, StorageAccountKey);

这里涉及到Azure Storage Account，必须为上篇博文中创建的事件中心MyEventHub指定一个存储账户和存储容器

增加MainAysnc方法：注册事件处理器，处理事件消息

        /// <summary>
        /// 注册事件处理器
        /// </summary>
        /// <param name="args"></param>
        /// <returns></returns>
        private static async Task MainAsync(string[] args)
        {
            Console.WriteLine("Registering EventProcessor...");

            var eventProcessorHost = new EventProcessorHost(
                EhEntityPath,
                PartitionReceiver.DefaultConsumerGroupName,
                EhConnectionString,
                StorageConnectionString,
                StorageContainerName);

            // Registers the Event Processor Host and starts receiving messages
            await eventProcessorHost.RegisterEventProcessorAsync<MyEventProcessor>();

            Console.WriteLine("Receiving. Press ENTER to stop worker.");
            Console.ReadLine();

            // Disposes of the Event Processor Host
            await eventProcessorHost.UnregisterEventProcessorAsync();
        }

Main函数

        static void Main(string[] args)
        {
            MainAsync(args).GetAwaiter().GetResult();
        }

Run

至此，我们实现了事件消息发送到Event Hub，同时从Event Hub接收处理事件消息。

周国庆

2017/5/18