What is Confluent and how does it differ from Apache Kafka?

Apache Kafka is the open-source project — you install, manage, monitor, and operate it yourself. Confluent was founded by the original creators of Kafka (Jay Kreps, Neha Narkhede, Jun Rao) and builds a commercial platform on top of Apache Kafka with enterprise features, managed cloud offering, and support.

Confluent Key Components — what you get extra

1. Schema Registry

The most important Confluent feature. In Apache Kafka, producers and consumers agree on message format by convention — if a producer changes the schema, consumers break silently. Schema Registry enforces a contract: producers register schemas, consumers validate against them. Supports Avro, JSON Schema, Protobuf.

• Schema evolution — backward compatible changes (add optional field) are allowed. Breaking changes (remove required field) are rejected by the registry.
• Serialisation — instead of raw bytes, messages are serialised with schema ID embedded. Consumer knows exactly how to deserialise.
• Real scenario: Telecom alarm events (TeMIP/SRO) have strict schemas. Producer sends alarm with 15 fields. Without Schema Registry: if a field is renamed, 10 downstream consumers silently fail. With Schema Registry: breaking change is rejected at produce time.

2. ksqlDB — SQL on Kafka Streams

Write SQL-like queries on live Kafka streams without writing Java or Python code. Create streaming aggregations, joins, and filters that run continuously.

-- Count errors per service in real-time (sliding 5-minute window)
CREATE TABLE error_counts AS
  SELECT service_name,
         COUNT(*) as error_count
  FROM application_logs
  WINDOW TUMBLING (SIZE 5 MINUTES)
  WHERE log_level = 'ERROR'
  GROUP BY service_name;

-- Join two streams: payment events + fraud signals
CREATE STREAM payment_risk AS
  SELECT p.payment_id, p.amount, f.risk_score
  FROM payments p
  LEFT JOIN fraud_signals f
  WITHIN 30 SECONDS
  ON p.user_id = f.user_id;

3. Confluent Control Center

Enterprise monitoring UI — topic browser, consumer group lag dashboard, schema management, connector management, alert configuration. Replaces the need for custom Grafana dashboards for Kafka monitoring.

4. Kafka Connect — Managed Connectors

Move data between Kafka and external systems without writing code. Confluent provides 100+ certified connectors:

• Source connectors — pull data INTO Kafka: Debezium (database CDC), S3, Salesforce, PostgreSQL
• Sink connectors — push data FROM Kafka: Elasticsearch, S3, Snowflake, MongoDB, Azure Blob

# Debezium PostgreSQL CDC connector — capture every DB change as Kafka event
{
  "name": "postgres-source",
  "config": {
    "connector.class": "io.debezium.connector.postgresql.PostgresConnector",
    "database.hostname": "postgres",
    "database.port": "5432",
    "database.user": "debezium",
    "database.password": "${file:/kafka/connect/secrets.properties:db.password}",
    "database.dbname": "telecom_sro",
    "table.include.list": "public.alarms,public.service_events",
    "topic.prefix": "dbserver1"
  }
}
# Every INSERT/UPDATE/DELETE on alarms table → Kafka topic event
# Downstream services react in real-time without polling the database

Confluent Cloud — when to use it

Confluent Cloud is Kafka as a fully managed service on AWS, Azure, or GCP. You create topics, set retention, configure producers/consumers — Confluent handles brokers, ZooKeeper/KRaft, replication, upgrades, disk management, and scaling. Pricing is based on Confluent Units (CUs) for compute and GB for storage and networking.

Confluent in Interviews — what to say

When asked about Kafka in senior interviews, distinguishing Apache Kafka from Confluent shows depth:

"I have used Apache Kafka on Kubernetes with Strimzi Operator for the TeMIP/SRO telecom platform at HPE. I understand Confluent's additional value — particularly Schema Registry for enforcing message contracts across microservices, and ksqlDB for streaming analytics without writing consumer code. For teams wanting managed Kafka, Confluent Cloud removes the operational complexity. For our platform, we chose Strimzi on OpenShift to keep data within the customer's infrastructure due to telco compliance requirements."