Today we are going to investigate how to set up a fabric network with kafka and zookeeper. As a beginner, first we need to understand what is kafka and zookeeper.


Apache Kafka

Apache Kafka is an open-source stream-processing software platform0.

Kafka is a distributed, horizontally-saclable, fault-tolerant, commit log1.

Since commit log is a record of transactions, Kafka can easily integrates with blockchain platform. Therefore, I think this is the reason why the first “consensus” of Fabric is utilising Kafka while the next would be based on Raft2.


Zookeeper is a general purpose distribtued process coordination system, it helps to coordinate tasks, manage state, configure, etc accross a distributed system.

Ordering Service

Ordering Service consists of orderers, providing a shared communication channel to clients and peers and offering a broadcast service for messages containing transactions.

OSN (Ordering Service Node/ Orderer Node): connected with the endorsers and peers

Understanding the role of ordering service in fabric network

Fabric transaction flow

Image Source: Hyperledger Fabric: A Distributed Operating System for Permissioned Blockchains


  • For kafka & zookeep, refer to this


Disclaimer: this is based on fabric-samples/first-network


  1. If kafka is a streaming-process software, why are we calling kafka-consensus in fabric?
  • First, we need to understand what is consensus. The definition of consensus is a general agreement3 and in the context of blockchain, it means all nodes must agree to the same order of transactions/blocks to achieve a universal shared ledger
  • Kafka provides the same order of transactions among multiple nodes by a shared queue as ordering nodes send to Kafka transactions and receive from Kafka transactions in the same order.

  1. Wiki page of kafka
  2. Through INtroduction to Apache Kafka
  3. Fabric Proposal: A Raft-Based Ordering Service
  4. Search Result of consensus