WHAT IS STATE MACHINE REPLICATION?

In the last discussion we are looking into the permission blockchain settings and in the context of permission blockchain the concept of state machine replication which will help you to achieve a consensus in a permission model.

· Use state machine replication- execute the contract at a subset of nodes and ensure that the same state is propagated to all the nodes.

· There is do not need to execute a smart contract to all the nodes rather you can execute it on a subset of nodes.

· Then you can ensure that the state of the contract is getting propagated to all the nodes in the network.

· There are certain consensus mechanism which will ensure you that well the states which have been propagated by multiple state machines or the contract executor they are indeed on the same page or they are indeed correct.

· So by applying this kind of distributed state machine replication technology you can ensure consensus in a  permission blockchain environment.

State machine

A set of states (S) based on the system design:

1. A set of inputs (i)

2. A set of outputs (o)

3. A transaction function S×I →s

4. A output function s×I →o

5. A start state

Understand what is mean by a state machine replication,

1. a state machine can be characterized by a set of parameters,

2. the set of parameters are a set of states based on the system design,

3. here in this particular example, you have three states S1, S2 and S3

4. you have a set of inputs which will tell you about how your system will behave.

· so here are two inputs 0 can be one input to the system and 1 can be another input to the system.

· then you have a set of outputs so here history is the final output of the system that is represented by the state machine a transition function

· so the transition function will take a state and an input as its input and it will produce a set as the output

· so here from state S1 if you take 0 as an input it produces state S2  output so this is a transition function then you have output function which may produce the output of the system so this particular example.

· we do not have any output but it may happen that well if you have an S1 and input as zero you are moving to state s2 that is your transition function and at the same time you may producing as output to zero

· so that way for certain state machines you may have an output function and there would be a designated state so here so on is denoted as the start state of the system now any algorithm any finite state machine which represents an algorithm that can be represented using a finite state machine.