[GitHub] [iotdb] SzyWilliam commented on a change in pull request #5396: [IOTDB-2833] Add readme to consensus

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SzyWilliam commented on a change in pull request #5396:
URL: https://github.com/apache/iotdb/pull/5396#discussion_r840991737



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File path: consensus/README.md
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@@ -0,0 +1,122 @@
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+
+# Overview
+The Consensus Package provides the Consensus Layer's service definitions and its implementations.
+ 
+### What is Consensus Layer used for?
+Generally, We maintain multiple copies of application data for the purpose of fault-tolerance and data-integrity.
+There are variety of consensus algorithms to manage multiple copies of data, which differs in levels of data consistency and performance.
+Each consensus algorithm may have multiple industrial implementations.
+The Consensus Layer aims to hide all complications behind different consensus algorithms and implementations, providing higher level of abstraction to the user.
+
+# Consensus Layer
+### Basic Concepts
+
+* `IStateMachine` is the user application that manages a local copy of data.
+* `Peer` is the smallest consensus unit (inside a process), which holds a `IStateMachine` internally.
+* `ConsensusGroup` is a group of `Peer` all managing the same copy of data.
+* `IConsensus` interface defines the basic functionality provided by Consensus Layer. 
+
+User application can create a `ConsensusGroup` with k `Peer` to store data, 
+i.e. that there will be k copies of data.
+
+When write data into a `ConsensusGroup` using `IConsensus::write`, it will be sent to the group leader's `IStateMachine::write` . 
+The leader makes decision about this write operation, 

Review comment:
       okay, I'll fix the term.




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