Upgrades/Updates

Target release
Epic
Document status	DRAFT
Document owner	Medha Parlikar (Unlicensed)
Designer
Developers
QA

Goals

Release upgrades to the RChain platform

Background and strategic fit

There needs to be a way that platform updates can be released in such a way that node operators know when the upgrade takes effect. In non-shared blockchain implementations, this is handled by block height. However, RChain aims to be sharded, which means that the block height mechanism probably won't work.

Assumptions

Each shard will have its own block DAG
Within each shard, the block DAG will add new blocks at different rates.
Updates need to be released and installed on the node well in advance of the date when the update takes effect. Particularly for changes to the protocol, where a hard fork is likely.
Not all validators will accept an update. If that is the case, the network will fork.

Requirements

#	Title	User Story	Importance	Notes
1	Accept updates	As a validator, I want to control whether I accept an update or not	Must Have	Each shard has the option to accept an update or not. Validators that don't want to take on the update, have an option to unbond from their current shard and bond to another shard.
2	Shard version number?	As a validator, I want to select a shard that is running a specific version of the RChain protocol	Must Have	Each shard publishes the version of the protocol it is running in the block information.
3	Consensus on updates?	As a validator, I would like to apply the update as the same time as the other validators in my shard, so that our shard doesn't have a fork	Nice to Have	It would be really smooth if the validator set could come to consensus on when the update takes effect. This way an entire shard could update at once.

User interaction and design

Questions

Below is a list of questions to be addressed as a result of this requirements document:

Question	Outcome
When will a feature take effect?

RChain wiki