Ethereum: Görli testnet ready for experimentation

The Görli testnet — which in accordance with testnet tradition, is named after a nearby train station — has come to Ethereum, and is now running in prototype form.

It is the first Proof-of-Authority network that works across multiple clients written in different languages; and aims to provide a universal and consistently available testnet.

After a few issues with node compatibility, and problems with validators being offline, an admittedly shaky version of the testnet is now live, under the label "pre-testnet v0.2".

Görli beginnings

Work on the testnet began at the ETHBerlin hackathon in early September, when Parity’s Afri Scohedon banded together with Chainsafe Systems in a bid to create a "next-generation public Ethereum test network". The team started porting Aura — the Proof-of-Authority consensus engine used on the Kovan testnet which is exclusively for Parity nodes, on to GETH. And, also porting Clique — the Proof-of-Authority consensus engine used on the Rinkeby testnet which is exclusively for GETH nodes, on to Parity.

A few days after winning the hackathon, Schoedon issued a call for wider participation in the project, citing the lack of a reliable, testnet that can be used with different Ethereum client implementations, and the need for a network that is responsive to the latest changes to long-term scaling plans.

"If you’ve ever tried to use a testnet on the various Ethereums you’ve likely encountered issues including the need to mine your own blocks, client incompatibility, and difficulty getting transactions included in blocks. These issues vary depending on which chain you’re using but ultimately it means that developers, especially new ones, experience substantial friction testing their applications in a live environment," wrote Ethereum Classic developer Anthony Lusardi, who granted the Goerli team $125,000 towards their efforts on behalf of the ETC cooperative.

The Görli testnet

Best practice before smart contracts are deployed to the Ethereum mainnet is to put them through their paces on a testnet, which allows developers to interact with working prototypes without disrupting normal network activity, and without incurring costs.

Instead of having to buy ethereum to pay for the gas needed to run smart contracts on the mainnet, developers can experiment on a free, testing network that mimics the environment of the mainnet. One way of creating this environment on a testnet is by using the Proof-of-Authority consensus mechanism, which does not require significant hashpower to run.

Proof-of-Authority

Similar to the Proof-of-Stake consensus mechanism that Ethereum is transitioning to with Casper, Proof-of-Authority consensus networks are protected by a set group of validator nodes.

Unlike Proof-of-Stake, however, Proof-of-Authority also requires individuals to have their identities checked in the real world, increasing the network’s capacity but also making it more vulnerable to centralization.

As there are specific requirements that must be met to act as a validator, there are less validators on the network, and so the system is less secure. Hence, Proof-of-Authority is almost never used to secure large, permissionless blockchains, but often put to use on private permissioned networks — lIke Microsoft’s Azure — and on small networks where the consequences of centralization are not significant (like a testnet).

This consensus mechanism is already implemented on two existing Ethereum testnets: Kovan and Rinkeby. However, because these two testnets use different variations of the consensus mechanism — Aura and Clique respectively — they are completely cut off from each other: Kovan, launched in March 2017 after a major attack on the Ropsten testnet, works only with the Parity client, and Rinkeby, launched shortly afterwards, works only with Geth.

Görli, on the other hand, represents a new network where both of Ethereum’s primary clients — Parity and Geth — can work as the validators of a single testnet, creating a single environment for testing, and making life easier for developers.

"There are many Ethereum testnets available for experimenting with smart contracts and deploying decentralized applications before going live on the main Ethereum network. However, there is no testnet available that is both widely usable across all client implementations, and robust enough to guarantee consistent availability and high reliability."Schoeden said in a call for participation.

Though an official launch is not yet scheduled, and lead developer Schoeden warns that "it might break any time", for now, Görli is usable by any Ethereum client supporting the Clique engine, with Parity support expected to follow shortly.