Polkadot Launches Testnet for Sharding Cross-Communication

The Polkadot project launched a testnet to evaluate its planned sharding implementation based on parachains.

The key component that separates shards from being just many independent blockchains is communication.

Called Rococo, the new testnet is designed specifically to test Polkadot's inter-shard communication protocols.

At launch, three separate parachains called tick, trick, and track will be available.

At launch, Rococo supports Horizontal Message Passing - a way of sending messages and thus tokens between parachains by going through the Relay Chain.

Polkadot's eventual goal is to implement Cross-Chain Message Passing, which would avoid using the relay chain to pass messages and thus enable quicker and more direct communication.

The Rococo testnet is an important milestone in Polkadot's complete sharding rollout, as currently the blockchains are largely isolated entities.

Polkadot's architecture is based on the concept of parachains, which are independent but cross-communicating blockchains.

Parachains are themselves based on Substrate, which is a blockchain building framework that provides the software foundation for parachains.

Substrate-based blockchains can be used in stand-alone mode as well, but a framework called Cumulus makes it very easy to integrate them into Polkadot.