Selgitage, kuidas erinevad sõnumite töötlemise süsteemides Consumer ja Consumer Group kontseptsioonid.

In message processing systems (e.g., Kafka), the concepts of Consumer and Consumer Group have the following differences:

• Consumer — is a separate process or thread that reads messages from a topic.

• Consumer Group — is a set of Consumers that collectively read messages from the same topic, distributing the load.

Main differences:

1. Message distribution:

   • One Consumer reads all messages from the topic (or from assigned partitions).
   • In a Consumer Group, the topic's partitions are distributed among Consumers so that each receives a unique set of messages.

2. Scalability:

   • A Consumer Group allows scaling processing by adding new Consumers.

3. Delivery guarantee:

   • Within a Consumer Group, each message is processed exactly by one Consumer.

Example: if a topic has 4 partitions and the group consists of 2 Consumers, each will read from 2 partitions, enabling parallel processing.

This allows efficient load distribution and fault tolerance.