software.amazon.kinesis.coordinator.migration

Interface MigrationStateMachine

All Known Implementing Classes:

MigrationStateMachineImpl

public interface MigrationStateMachine

State machine that provides: 1. Seamless upgrade from 2.x to 3.x - 3.x has introduced new algorithms that are not compatible with 2.x workers, so the state machine allows to seamlessly run the 2.x functionality to be compliant with any 2.x worker in the fleet, and also seamlessly switch to 3.x functionality when all KCL workers are 3.x complaint. 2. Instant rollbacks - Rollbacks are supported using the KCL Migration tool to revert back to 2.x functionality if customer finds regressions in 3.x functionality. 3. Instant roll-forwards - Once any issue has been mitigated, rollfowards are supported instantly with KCL Migration tool.

Method Summary

Modifier and Type	Method and Description
ClientVersion	getCurrentClientVersion() Get the ClientVersion of current state machine state.
void	initialize() Initialize the state machine by identifying the initial state when the KCL worker comes up for the first time.
void	shutdown() Shutdown state machine and perform necessary cleanup for the worker to gracefully shutdown
void	terminate() Terminate the state machine when it reaches a terminal state, which is a successful upgrade to v3.x.
void	transitionTo(ClientVersion nextClientVersion, MigrationState state) Peform transition from current state to the given new ClientVersion

Method Detail

initialize

void initialize()
         throws DependencyException

Initialize the state machine by identifying the initial state when the KCL worker comes up for the first time.

Throws:

DependencyException - When unable to identify the initial state.

shutdown

void shutdown()

Shutdown state machine and perform necessary cleanup for the worker to gracefully shutdown

terminate

void terminate()

Terminate the state machine when it reaches a terminal state, which is a successful upgrade to v3.x.

transitionTo

void transitionTo(ClientVersion nextClientVersion,
                  MigrationState state)
           throws InvalidStateException,
                  DependencyException

Peform transition from current state to the given new ClientVersion

Parameters:

nextClientVersion - clientVersion of the new state the state machine must transition to

state - the current MigrationState in dynamo

Throws:

InvalidStateException - when transition fails, this allows the state machine to stay in the current state until a valid transition is possible

DependencyException - when transition fails due to dependency on DDB failing in unexpected ways.

getCurrentClientVersion

ClientVersion getCurrentClientVersion()

Get the ClientVersion of current state machine state.

Returns:

ClientVersion of current state machine state