Cross-chain communication is a cross-chain technology. Unlike Plasma, there is no strong primary and secondary relationship between two chains. Sub-chains and side chains still have the right to generate their own assets and run their own operations, and then cross-chain interaction with the main chain or other chains through some protocol.
It is not Layer 2 of Layer 1 strictly speaking, but it is very beneficial to the improvement of Scability of the whole system. So I’m going to give you a little bit of an idea of two projects.
Cosmos
The Cosmos system architecture is shown in the figure. There is a Cosmos Hub in the middle, and the Zone around it can be regarded as an exchange chain, and the other parts around it are sub-chains. Zone is made in Tendermint, using BFT consensus and blockchain framework, it also satisfies Instant Finality, if the system is less than 1/3 evil nodes, it must be correct. It introduces inter-Blockchain Communication (IBC), a protocol similar to Plasma and State Channel.
The simple process is as follows: Chains A and B are zones.
- The user locks 10 coins on the A chain
- Ten locked cryptographic certificates on chain A were submitted to chain B
- It is valid if validated by 2/3 of the verifier.
- So we’re going to have 10 coins on chain B
The Cosmos Hub is required because it can change the number of IBCs created between zones from N^2 to N, but this is conditional on the fact that all zones must be Instant Finality. If you give me proof, I will believe that your coins are locked there. I can’t get it out, it can’t be probabilistically confirmed, it can’t be generated here and overturned there. But since Bitcoin and Ethereum are probabilistic confirmation chains, Cosmos can’t connect to them, so it makes a Peg Zone, which is a proxy chain, which makes a proxy chain for the probabilistic confirmation chain, so Cosmos can interact with them.
Polkadot
Polkadot is a very sophisticated project compared to Cosmos, but its architecture is almost identical to that of Cosmos. Relay Chain is the Hub in the Cosmos, and Para Chain is the Zone in the Cosmos. Para Chain uses the framework of Parity Substrate. The Chain is BFT based, so it is Instant Finality, which will also encounter the problem of connecting probability-confirmed blockchain. So it introduces the concept of a Bridge Chain, which is the same as the Peg Zone of Cosmos. However, Polkadot’s Parity Substrate is a better Substrate than Cosmos’s Tendermint. Polkadot’s founders have made an upgrade to Rust’s VM and BFT implementation that speeds up the consensus protocol by adding randomly elected validation nodes, so it’s very fast, and it’s also very capable of deploying smart contracts and upgrading nodes. Moreover, Substrate introduces a more sophisticated governance mechanism than other chains.
Security mechanism
Read on:
Layer2 | State Channel State Channel
Layer2 | Plasma framework
Under the Layer2 | chain is calculated
Communication between Layer2 | chain