Metropolis (Ethereum) Definition
What is Metropolis?
Metropolis is the third phase in Ethereum’s four-step roadmap to improve its blockchain. The goal of the overall upgrade is to make the platform more secure and scalable.
The Metropolis phase, which is a hark fork of the blockchain, is divided into two parts, Byzantium and Constantinople:
The first step of the Metropolis update involves a total of nine Ethereum improvement protocols. Changes include addressing the issue of difficulty adjustments, “returndata” operations, “static call” operations, new precompiles, adding difficulty delay feature, and embedding transaction return data in receipts.
One important component of the Metropolis update is its inclusion of the building blocks for zero-knowledge proofs, or ZK-SNARKs, down the road. ZK-SNARKs will increase anonymity for the ecosystem.
The Byzantium upgrade was successfully executed on October 16, 2017 on block number 4.37 million and is running smoothly.
The second step of the Metropolis update has more unknowns than Byzantium, but it will shed light on the hybrid Proof of Stake / Proof of Work blockchain. It will set the foundations for the Casper update, which will fully implement PoS mining.
This leg also includes EIP 86, which brings account abstraction to the Ethereum network. This will allow users to have increased control over their private keys. It also lets smart contracts pay transaction fees, rather than requiring senders to settle GAS payments.
There is still no hard release date for Constantinople, but the road map places it some time in 2018.
Unlike the split between Ethereum and Ethereum Classic, the Metropolis update will not result in a new Ethereum derived blockchain. The Metropolis update has been agreed upon for some time, and consensus will surely be reached. If the Constantinople upgrade is as smooth as Byzantium, the Casper upgrade could come relatively soon as well.