问题描述

创建Event Hub服务后，标准版的定价层功能中有Schema Registry的功能，但是根据官方文档，在门户中确无法创建。

问题解答

什么是 Azure 架构注册表？
Azure 架构注册表是事件中心的一项功能，它为事件驱动的应用程序和以消息为中心的应用程序的架构提供一个中心存储库。

它使生成者和使用者应用程序可以灵活地交换数据，而无需管理和共享架构。

它还为可重用架构提供了一个简单的治理框架，并通过分组构造（架构组）定义了架构之间的关系。

 使用 Apache Avro 等架构驱动的序列化框架，将序列化元数据移到共享架构还有助于降低每条消息的开销。 这是因为每条消息不需要像 JSON 等标记格式那样包含元数据 (类型信息和字段名称)。

将架构与事件一起存储，并将其存储在事件基础结构中，可确保序列化或反序列化所需的元数据始终是可访问的，并且架构始终置于正确的位置。

# REST API

PUT https://management.chinacloudapi.cn/subscriptions/<>/resourceGroups/<>/providers/Microsoft.EventHub/namespaces/<>/schemagroups/<>?api-version=2021-11-01

{
  "properties": {
    "groupProperties": {},
    "schemaCompatibility": "Forward",
    "schemaType": "Avro"
  }
}

参考资料：https://learn.microsoft.com/en-us/rest/api/eventhub/schema-registry/create-or-update?view=rest-eventhub-2021-11-01&tabs=HTTP

# Azure Cli

az eventhubs namespace schema-registry create --name
                                              --namespace-name
                                              --resource-group
                                              [--group-properties]
                                              [--schema-compatibility {Backward, Forward, None}]
                                              [--schema-type {Avro, Unknown}]

参考资料：https://learn.microsoft.com/en-us/cli/azure/eventhubs/namespace/schema-registry?view=azure-cli-latest

# 使用示例

在使用事件中心 .NET SDK (AMQP) 流式处理事件时使用 Avro 架构验证 ： https://learn.microsoft.com/zh-cn/azure/event-hubs/schema-registry-dotnet-send-receive-quickstart

发送消息

using Azure.Data.SchemaRegistry;
using Azure.Identity;
using Microsoft.Azure.Data.SchemaRegistry.ApacheAvro;
using Azure.Messaging.EventHubs;
using Azure.Messaging.EventHubs.Producer;

using Microsoft.Azure.Data.SchemaRegistry.example;

// connection string to the Event Hubs namespace
const string connectionString = "EVENTHUBSNAMESPACECONNECTIONSTRING";

// name of the event hub
const string eventHubName = "EVENTHUBNAME";

// Schema Registry endpoint 
const string schemaRegistryEndpoint = "EVENTHUBSNAMESPACENAME.servicebus.windows.net";

// name of the consumer group   
const string schemaGroup = "SCHEMAGROUPNAME";

// The Event Hubs client types are safe to cache and use as a singleton for the lifetime
// of the application, which is best practice when events are being published or read regularly.
EventHubProducerClient producerClient;

// Create a producer client that you can use to send events to an event hub
producerClient = new EventHubProducerClient(connectionString, eventHubName);

// Create a schema registry client that you can use to serialize and validate data.  
var schemaRegistryClient = new SchemaRegistryClient(schemaRegistryEndpoint, new DefaultAzureCredential());

// Create an Avro object serializer using the Schema Registry client object. 
var serializer = new SchemaRegistryAvroSerializer(schemaRegistryClient, schemaGroup, new SchemaRegistryAvroSerializerOptions { AutoRegisterSchemas = true });

// Create a new order object using the generated type/class 'Order'. 
var sampleOrder = new Order { id = "1234", amount = 45.29, description = "First sample order." };
EventData eventData = (EventData)await serializer.SerializeAsync(sampleOrder, messageType: typeof(EventData));

// Create a batch of events 
using EventDataBatch eventBatch = await producerClient.CreateBatchAsync();

// Add the event data to the event batch. 
eventBatch.TryAdd(eventData);

// Send the batch of events to the event hub. 
await producerClient.SendAsync(eventBatch);
Console.WriteLine("A batch of 1 order has been published.");       

消费消息

using Azure.Data.SchemaRegistry;
using Azure.Identity;
using Microsoft.Azure.Data.SchemaRegistry.ApacheAvro;
using Azure.Storage.Blobs;
using Azure.Messaging.EventHubs;
using Azure.Messaging.EventHubs.Consumer;
using Azure.Messaging.EventHubs.Processor;

using Microsoft.Azure.Data.SchemaRegistry.example;


// connection string to the Event Hubs namespace
const string connectionString = "EVENTHUBSNAMESPACECONNECTIONSTRING";

// name of the event hub
const string eventHubName = "EVENTHUBNAME";

// Schema Registry endpoint 
const string schemaRegistryEndpoint = "EVENTHUBSNAMESPACENAME.servicebus.windows.net";

// name of the consumer group   
const string schemaGroup = "SCHEMAGROUPNAME";

// connection string for the Azure Storage account
const string blobStorageConnectionString = "AZURESTORAGECONNECTIONSTRING";

// name of the blob container that will be userd as a checkpoint store
const string blobContainerName = "BLOBCONTAINERNAME";

// Create a blob container client that the event processor will use 
BlobContainerClient storageClient = new BlobContainerClient(blobStorageConnectionString, blobContainerName);

// Create an event processor client to process events in the event hub
EventProcessorClient processor = new EventProcessorClient(storageClient, EventHubConsumerClient.DefaultConsumerGroupName, connectionString, eventHubName);

// Register handlers for processing events and handling errors
processor.ProcessEventAsync += ProcessEventHandler;
processor.ProcessErrorAsync += ProcessErrorHandler;

// Start the processing
await processor.StartProcessingAsync();

// Wait for 30 seconds for the events to be processed
await Task.Delay(TimeSpan.FromSeconds(30));

// Stop the processing
await processor.StopProcessingAsync();

static async Task ProcessEventHandler(ProcessEventArgs eventArgs)
{
    // Create a schema registry client that you can use to serialize and validate data.  
    var schemaRegistryClient = new SchemaRegistryClient(schemaRegistryEndpoint, new DefaultAzureCredential());

    // Create an Avro object serializer using the Schema Registry client object. 
    var serializer = new SchemaRegistryAvroSerializer(schemaRegistryClient, schemaGroup, new SchemaRegistryAvroSerializerOptions { AutoRegisterSchemas = true });

    // Deserialized data in the received event using the schema 
    Order sampleOrder = (Order)await serializer.DeserializeAsync(eventArgs.Data, typeof(Order));

    // Print the received event
    Console.WriteLine($"Received order with ID: {sampleOrder.id}, amount: {sampleOrder.amount}, description: {sampleOrder.description}");

       await eventArgs.UpdateCheckpointAsync(eventArgs.CancellationToken);
    }

    static Task ProcessErrorHandler(ProcessErrorEventArgs eventArgs)
{
    // Write details about the error to the console window
    Console.WriteLine($"\tPartition '{eventArgs.PartitionId}': an unhandled exception was encountered. This was not expected to happen.");
    Console.WriteLine(eventArgs.Exception.Message);
    return Task.CompletedTask;
}