Apicurio Studio

Introduction to Apicurio Registry

Apicurio Registry overview

Apicurio Registry is a datastore for sharing standard event schemas and API designs across API and event-driven architectures. You can use Apicurio Registry to decouple the structure of your data from your client applications, and to share and manage your data types and API descriptions at runtime using a REST interface.

For example, client applications can dynamically push or pull the latest schema updates to or from Apicurio Registry at runtime without needing to redeploy. Developer teams can query the registry for existing schemas required for services already deployed in production, and can register new schemas required for new services in development.

You can enable client applications to use schemas and API designs stored in Apicurio Registry by specifying the registry URL in your client application code. For example, the registry can store schemas used to serialize and deserialize messages, which can then be referenced from your client applications to ensure that the messages that they send and receive are compatible with those schemas.

Using Apicurio Registry to decouple your data structure from your applications reduces costs by decreasing overall message size, and creates efficiencies by increasing consistent reuse of schemas and API designs across your organization. Apicurio Registry provides a web console to make it easy for developers and administrators to manage registry content.

In addition, you can configure optional rules to govern the evolution of your registry content. For example, these include rules to ensure that uploaded content is syntactically and semantically valid, or is backwards and forwards compatible with other versions. Any configured rules must pass before new versions can be uploaded to the registry, which ensures that time is not wasted on invalid or incompatible schemas or API designs.

Apicurio Registry capabilities

  • Support for multiple payload formats for standard event schemas and API specifications

  • Pluggable storage options including Apache Kafka, embedded Infinispan, or PostgreSQL database

  • Registry content management using a web console, REST API command, Maven plug-in, or Java client

  • Rules for content validation and version compatibility to govern how registry content evolves over time

  • Full Apache Kafka schema registry support, including integration with Kafka Connect for external systems

  • Client serializers/deserializers (Serdes) to validate Kafka and other message types at runtime

  • Cloud-native Quarkus Java runtime for low memory footprint and fast deployment times

  • Compatibility with existing Confluent schema registry client applications

  • Operator-based installation of Apicurio Registry on OpenShift

Schema and API artifacts in Apicurio Registry

The items stored in Apicurio Registry, such as event schemas and API specifications, are known as registry 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.

Apicurio 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 Apicurio Registry artifact reference.

Apicurio Registry storage options

Apicurio Registry provides the following underlying storage implementations for registry artifacts:

  • In-memory

  • Java Persistence API

  • Apache Kafka

  • Apache Kafka Streams

  • Embedded Infinispan cache

The in-memory storage option is suitable for a development environment only. All data is lost when restarting Apicurio Registry with this storage. The Kafka Streams storage option is recommended for production environments.

Manage content using Apicurio Registry web console

You can use the Apicurio Registry web console to browse and search the artifacts stored in the registry, and to upload new artifacts and artifact versions. You can search for artifacts by label, name, and description. You can also view an artifact’s content, view all of its available versions, or download an artifact file locally.

You can also use the Apicurio Registry web console to configure optional rules for registry content, both globally and for each artifact. These optional rules for content validation and compatibility are applied when new artifacts or artifact versions are uploaded to the registry. For more details, see Apicurio Registry artifact reference.

Apicurio Registry web console
Figure 1. Apicurio Registry web console

The Apicurio Registry web console is available from the main endpoint of your Apicurio Registry deployment, for example, on http://MY-REGISTRY-URL/ui.

Validate schemas with Kafka client serializers/deserializers

Kafka producer applications can use serializers to encode messages that conform to a specific event schema. Kafka consumer applications can then use deserializers to validate that messages have been serialized using the correct schema, based on a specific schema ID.

Registry Serdes architecture
Figure 2. Apicurio Registry and Kafka client serializer/deserializer architecture

Apicurio Registry provides Kafka client serializers/deserializers (Serdes) to validate the following message types at runtime:

  • Apache Avro

  • Google protocol buffers

  • JSON Schema

The Apicurio Registry Maven repository and source code distributions include the Kafka serializer/deserializer implementations for these message types, which Kafka 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.

Stream data to external systems with Kafka Connect converters

You can use Apicurio Registry with Apache Kafka Connect to stream data between Kafka and external systems. Using Kafka Connect, you can define connectors for different systems to move large volumes of data into and out of Kafka-based systems.

Registry and Kafka Connect architecture
Figure 3. Apicurio Registry and Kafka Connect architecture

Apicurio Registry provides the following features for Kafka Connect:

  • Storage for Kafka Connect schemas

  • Kafka Connect converters for Apache Avro and JSON Schema

  • Registry REST API to manage schemas

You can use the Avro and JSON Schema converters to map Kafka Connect schemas into Avro or JSON schemas. Those schemas can then serialize message keys and values into the compact Avro binary format or human-readable JSON format. The converted JSON is also less verbose because the messages do not contain the schema information, only the schema ID.

Apicurio Registry can manage and track the Avro and JSON schemas used in the Kafka topics. Because the schemas are stored in Apicurio Registry and decoupled from the message content, each message must only include a tiny schema identifier. For an I/O bound system like Kafka, this means more total throughput for producers and consumers.

The Avro and JSON Schema serializers and deserializers (Serdes) provided by Apicurio Registry are also used by Kafka producers and consumers in this use case. Kafka consumer applications that you write to consume change events can use the Avro or JSON Serdes to deserialize these change events. You can install these Serdes into any Kafka-based system and use them along with Kafka Connect, or with Kafka Connect-based systems such as Debezium and Camel Kafka Connector.

Apicurio Registry demonstration examples

Apicurio Registry provides an open source demonstration 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.

Apicurio Registry also provides the following example applications:

  • Simple Avro example

  • Simple JSON Schema example

  • Confluent Serdes integration

  • Avro bean example

  • Custom ID strategy example

  • Simple Avro Maven example

  • REST client example

Apicurio Registry available distributions

Table 1. Apicurio Registry images
Distribution option Container Image

In-memory

https://hub.docker.com/r/apicurio/apicurio-registry-mem

Java Persistence API

https://hub.docker.com/r/apicurio/apicurio-registry-jpa

Apache Kafka

https://hub.docker.com/r/apicurio/apicurio-registry-kafka

Apache Kafka Streams

https://hub.docker.com/r/apicurio/apicurio-registry-streams

Infinispan

https://hub.docker.com/r/apicurio/apicurio-registry-infinispan

Apicurio Registry Operator

https://hub.docker.com/r/apicurio/apicurio-registry-operator

Additional resources