Consuming Apache Kafka Messages via REST: Possibilities, Implementation, and Considerations

In the era of microservices and distributed systems, messaging systems like Apache Kafka play a critical role in enabling seamless communication between different components of an application. Traditionally, applications interact with Kafka using native Kafka clients, but what if we want to consume messages from Kafka using REST instead?

Is it Possible to Consume Messages from Apache Kafka via REST?

Yes, it is possible to consume messages from Apache Kafka using REST without requiring native Kafka clients. The solution to this problem is the Confluent Platform, which includes an open-source application called REST Proxy. This tool allows developers to produce, consume, and manage Kafka topics through a RESTful API, providing a layer of abstraction on top of the native Kafka protocol.

What is REST Proxy?

REST Proxy, part of the Confluent Platform, is a powerful tool designed to facilitate interaction with Apache Kafka. It works by converting REST requests into Kafka actions and vice versa. This means you can write your applications in virtually any programming language and still interact seamlessly with Kafka, thanks to the REST API.

Use Cases for REST Proxy

REST Proxy is particularly useful in scenarios where:

You are integrating with frontend apps built in different languages. Your stream processing framework does not have native Kafka support. You need to perform administrative actions on your Kafka cluster.

Examples of What You Can Do with REST Proxy

Here are some practical examples of operations you can perform with REST Proxy:

Getting a List of Topics

To get a list of all topics in your Kafka cluster, you can use the following curl command:

curl -X GET https:///topics

Getting Info About a Specific Topic

To get detailed information about a specific topic, use the following command:

curl -X GET https:///topic/

Producing a Message with JSON Data

To produce a message with JSON data, you can use the following curl command:

curl -X POST -H "Content-Type: application/vnd.kafka.json.v2 json" -d '{"key":"your-key", "value": {"field1":"value1", "field2":"value2"}}' https:///topics/

Creating a Consumer for JSON Data

To create a consumer for JSON data starting from the beginning of the topic's log, use the following command:

curl -X POST -H "Content-Type: json" -H "Accept: application/vnd.kafka.v2 json" https:///topic/ -d '{"topics": [""], "": "earliest"}'

Note that the consumer group used in this example is simply a placeholder. You should replace it with the actual consumer group name for your application.

Native vs. REST Consumption

For developers who don't want to use additional software and prefer a more straightforward approach, consuming Kafka messages natively is the way to go. However, if you are working in a cross-language environment, or if your current setup doesn't have native Kafka support, the Confluent REST Proxy offers a viable solution.

In scenarios where you need to integrate with frontend applications built in various languages, or perform administrative tasks without rewriting existing code, REST Proxy provides the flexibility and convenience required.

Options for Native Consumption

If you do not want to rely on additional software and prefer native Kafka consumption, you can explore the following options:

Consuming messages directly using Kafka clients (e.g., Kafka Java client, Python Kafka client). Developing a custom REST frontend that converts REST requests to Kafka actions.

However, these solutions require more setup and might be more complex to implement.

Conclusion

Consuming Apache Kafka messages via REST is a powerful feature enabled by the Confluent Platform's REST Proxy. This tool allows you to interact with Kafka in a more flexible and cross-language manner, making it an attractive option for modern distributed systems.

Whether you opt for native consumption or use REST Proxy, the choice ultimately depends on your specific use case and integration requirements. The flexibility offered by REST Proxy makes it a valuable addition to any Kafka ecosystem.

Keywords: Apache Kafka, REST Proxy, Confluent Platform