Overview

In the configuration, our applications behave as consumers that communicate with each other to complete processes. They use a JSON format to send and receive messages. Consumer groups are used to scale our applications and share the same identifier. For example, when two model controllers coexist, each one is a consumer and they both belong to the same consumer group.

A topic is the data structure Kafka uses to store and distribute messages. Topics organize messages in partitions. Consumers are attached to different topics. When a topic receives a message, it sends it to a consumer group. Just one of the group’s consumers receives the message. The consumer array contains all connections receiving messages from a topic. Learn more about topic configuration here.

The groups object

{
  "teamState": "",
  "teamId": "",
  "consumer": []
}

Parameter	Type	Description
teamState	string	The team’s status. Values can be `Stable` (the consumers are ready to receive messages), `Dead` (a consumer has an error), `Empty` (it doesn’t have any consumers), `PreparingRebalance` (it’s distributing partitions to new consumers), `CompletingRebalance` (it’s completing the distribution), and `Unknown`.
teamId	string	The team’s identifier.
consumer	array	An array of consumers.

The consumers object

{
  "topicPartitions": [],
  "consumerId": "",
  "clientId": ""
}

Parameter	Type	Description
topicPartitions	array	An array of topic partition objects.
consumerId	string	The consumer’s identifier. Applications may have a different consumers for each instance.
clientId	string	The client application’s identifier.

The topics object

{
  "consumerApplication": "",
  "producedBy": "",
  "topic": "",
  "description": "",
  "data": {}
}

Parameter	Type	Description
consumerApplication	string	The application that consumes the topic’s messages.
producedBy	string	The application that produces the topic’s messages.
topic	string	The topic’s name.
description	string	The consumer’s action after it receives the message.
data	object	The team’s object.

The topics partition object

{
  "topic": "",
  "partition": 0,
  "byteSize": -1,
  "offset": {}
}

Parameter	Type	Description
topic	string	The topic’s identifier.
partition	number	The partition’s index number.
byteSize	number	The disk space used by the partition in bytes. Its value is -1 if the partition has never used its disk space.
offset	object	The offset object.

The offset object

{
  "currentOfConsumer": 44562,
  "lastOfTopic": 44562,
  "lag": 0
}

Parameter	Type	Description
currentOfConsumer	number	The last consumed message’s index.
lastOfTopic	number	The last message index available in the partition.
lag	number	The difference between the last consumed message’s index and the newest message’s index for a consumer in the topic.