Chapter 1. Introduction to Service Registry

The items stored in Service Registry, such as event schemas and API specifications, are known as artifacts. The following shows an example of an Apache Avro schema artifact in JSON format for a simple share price application:

{
   "type": "record",
   "name": "price",
   "namespace": "com.example",
   "fields": [
       {
           "name": "symbol",
           "type": "string"
       },
       {
           "name": "price",
           "type": "string"
       }
   ]
}

When a schema or API contract is added as an artifact in the registry, client applications can then use that schema or API contract to validate that client messages conform to the correct data structure at runtime.

Service Registry supports a wide range of message payload formats for standard event schemas and API specifications. For example, supported formats include Apache Avro, Google protocol buffers, GraphQL, AsyncAPI, OpenAPI, and others. For more details, see Section 1.2, “Supported artifact types”.

Using the Registry REST API, client applications can manage the artifacts in Service Registry. This API provides create, read, update, and delete operations for:

For detailed information, see the Apicurio Registry REST API documentation.

Service Registry supports the following underlying storage implementations for artifacts:

Event-based producer applications can use serializers to encode messages that conform to a specific event schema. Consumer applications can then use deserializers to validate that messages have been serialized using the correct schema, based on a specific schema ID. Service Registry provides client serializers/deserializers to validate the following message types at runtime:

The Service Registry Maven repository and source code distributions include the serializer/deserializer implementations for these message types, which client developers can use to integrate with the registry. These implementations include custom io.apicurio.registry.utils.serde Java classes for each supported message type, which client applications can use to pull schemas from the registry at runtime for validation.

Service Registry provides an open source demonstration example of Apache Avro serialization/deserialization with storage in Apache Kafka Streams. This example shows how the serializer/deserializer obtains the Avro schema from the registry at runtime and uses it to serialize and deserialize Kafka messages. For more details, see https://github.com/Apicurio/apicurio-registry-demo.

This demonstration also provides simple examples of both Avro and JSON Schema serialization/deserialization with storage in Apache Kafka: https://github.com/Apicurio/apicurio-registry-demo/tree/master/src/main/java/io/apicurio/registry/demo/simple

For another demonstration example with detailed instructions on Avro serialization/deserialization with storage in Apache Kafka, see the Red Hat Developer article on Getting Started with Red Hat Integration Service Registry.