Microsoft.Azure.Data.SchemaRegistry.ApacheAvro

Azure Schema Registry Apache Avro client library for .NET

Azure Schema Registry is a schema repository service hosted by Azure Event Hubs, providing schema storage, versioning, and management. This package provides an Avro encoder capable of encoding and decoding payloads containing Schema Registry schema identifiers and Avro-encoded data.

Getting started

Install the package

Install the Azure Schema Registry Apache Avro library for .NET with NuGet:

dotnet add package Microsoft.Azure.Data.SchemaRegistry.ApacheAvro --version 1.0.0-beta.1

Prerequisites

• An Azure subscription
• An Event Hubs namespace

If you need to create an Event Hubs namespace, you can use the Azure Portal or Azure PowerShell.

You can use Azure PowerShell to create the Event Hubs namespace with the following command:

New-AzEventHubNamespace -ResourceGroupName myResourceGroup -NamespaceName namespace_name -Location eastus

Authenticate the client

In order to interact with the Azure Schema Registry service, you'll need to create an instance of the Schema Registry Client class. To create this client, you'll need Azure resource credentials and the Event Hubs namespace hostname.

Get credentials

To acquire authenicated credentials and start interacting with Azure resources, please see the quickstart guide here.

Get Event Hubs namespace hostname

The simpliest way is to use the Azure portal and navigate to your Event Hubs namespace. From the Overview tab, you'll see Host name. Copy the value from this field.

Create SchemaRegistryClient

Once you have the Azure resource credentials and the Event Hubs namespace hostname, you can create the SchemaRegistryClient. You'll also need the Azure.Identity package to create the credential.

// Create a new SchemaRegistry client using the default credential from Azure.Identity using environment variables previously set,
// including AZURE_CLIENT_ID, AZURE_CLIENT_SECRET, and AZURE_TENANT_ID.
// For more information on Azure.Identity usage, see: https://github.com/Azure/azure-sdk-for-net/blob/main/sdk/identity/Azure.Identity/README.md
var schemaRegistryClient = new SchemaRegistryClient(fullyQualifiedNamespace: fullyQualifiedNamespace, credential: new DefaultAzureCredential());

Key concepts

Encoder

This library provides an encoder, [SchemaRegistryAvroEncoder] schema_registry_avro_encoder, that interacts with EventData events. The SchemaRegistryAvroEncoder utilizes a SchemaRegistryClient to enrich the EventData events with the schema ID for the schema used to encode the data.

This encoder requires the Apache Avro library. The payload types accepted by this encoder include GenericRecord and ISpecificRecord.

Examples

The following shows examples of what is available through the SchemaRegistryAvroEncoder. There are both sync and async methods available for these operations. These examples use a generated Apache Avro class Employee.cs created using this schema:

{
   "type" : "record",
    "namespace" : "TestSchema",
    "name" : "Employee",
    "fields" : [
        { "name" : "Name" , "type" : "string" },
        { "name" : "Age", "type" : "int" }
    ]
}

Details on generating a class using the Apache Avro library can be found in the Avro C# Documentation.

Encode and decode data using the Event Hub EventData model

In order to encode an EventData instance with Avro information, you can do the following:

var encoder = new SchemaRegistryAvroEncoder(client, groupName, new SchemaRegistryAvroEncoderOptions { AutoRegisterSchemas = true });

var employee = new Employee { Age = 42, Name = "Caketown" };
EventData eventData = (EventData) await encoder.EncodeMessageDataAsync(employee, messageType: typeof(EventData));

// the schema Id will be included as a parameter of the content type
Console.WriteLine(eventData.ContentType);

// the serialized Avro data will be stored in the EventBody
Console.WriteLine(eventData.EventBody);

To decode an EventData event that you are consuming:

Employee deserialized = (Employee) await encoder.DecodeMessageDataAsync(eventData, typeof(Employee));
Console.WriteLine(deserialized.Age);
Console.WriteLine(deserialized.Name);

You can also use generic methods to encode and decode the data. This may be more convenient if you are not building a library on top of the Avro encoder, as you won't have to worry about the virality of generics:

var encoder = new SchemaRegistryAvroEncoder(client, groupName, new SchemaRegistryAvroEncoderOptions { AutoRegisterSchemas = true });

var employee = new Employee { Age = 42, Name = "Caketown" };
EventData eventData = await encoder.EncodeMessageDataAsync<EventData, Employee>(employee);

// the schema Id will be included as a parameter of the content type
Console.WriteLine(eventData.ContentType);

// the serialized Avro data will be stored in the EventBody
Console.WriteLine(eventData.EventBody);

Similarly, to decode:

Employee deserialized = (Employee) await encoder.DecodeMessageDataAsync<Employee>(eventData);
Console.WriteLine(deserialized.Age);
Console.WriteLine(deserialized.Name);

Encode and decode data using MessageWithMetadata directly

It is also possible to encode and decode using MessageWithMetadata. Use this option if you are not integrating with any of the messaging libraries that work with MessageWithMetadata.

var encoder = new SchemaRegistryAvroEncoder(client, groupName, new SchemaRegistryAvroEncoderOptions { AutoRegisterSchemas = true });
MessageWithMetadata messageData = await encoder.EncodeMessageDataAsync<MessageWithMetadata, Employee>(employee);

Employee decodedEmployee = await encoder.DecodeMessageDataAsync<Employee>(messageData);

Troubleshooting

Information on troubleshooting steps will be provided as potential issues are discovered.

Next steps

See Azure Schema Registry for additional information.

Contributing

This project welcomes contributions and suggestions. Most contributions require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us the rights to use your contribution. For details, visit cla.microsoft.com.

When you submit a pull request, a CLA-bot will automatically determine whether you need to provide a CLA and decorate the PR appropriately (e.g., label, comment). Simply follow the instructions provided by the bot. You will only need to do this once across all repos using our CLA.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact [email protected] with any additional questions or comments.