The first shared Sequencer technology is launched on the Polygon zkEVM testnet

Author: Bessie Liu Source: blockworks Compilation: Shan Ouba, Golden Finance

Blockchain infrastructure company Espresso’s has released a testnet version of Espresso Sequencer, which is based on a forked version of the Polygon zkEVM. A testnet called "Doppio" is already running within the company and will be opened to external nodes in the coming months. The Sequencer is responsible for ordering transactions from the mempool and sending the information back to the virtual machine. Similar to validators on a Layer-1 network, they play a vital role in running a Layer-2 blockchain network.

Currently, Sequencer is still relatively centralized. Rollups run their own independent Sequencer and have their own execution environment - and in the case of zero-knowledge (ZK) Rollups, they also have their own proof system.

Espresso co-founder and head of strategy Jill Gunter explained in an interview with Blockworks that the existing Sequencer is relatively monolithic in operation. "In existing Rollup solutions, the Sequencer is just a component that is bundled with the rest of the Rollup software. There's nothing in the way that's programmable, upgradable, or replaceable," Gunter said. As a result, many Rollups today experience some sort of The degree of downtime, which Gunter believes is downplayed in today's Rollup environment. "It's not catastrophic because you can always force transactions back to [Layer-1]. But it can be costly and raises what I call the soft censorship problem, where transactions aren't being prioritized," she said. .”

**How does Espresso's decentralized Sequencer work? **

Espresso designed its own proprietary proof-of-stake system, HotShot, which will be used to optimize the balance of performance while maintaining decentralization and robustness, Gunter explained.

"It's a distributed consensus system that can be shared between different Rollups, so Rollups no longer need to bundle Sequencer in their own software stack," she said. "They will use Espresso [application programming interface] to call and Submit the transaction to Espresso Sequencer."

Espresso Sequencer has two main functions: First, it performs data availability as an option, which means that if a Rollup wants data availability as an additional function, they can choose to use it. Second, it enforces consensus on the order of transactions.

"Espresso Sequencer can perform both of these functions across multiple rollups, and when you start doing cross-rollup sequencing, all sorts of interesting situations arise," Gunter said. MEV (Maximize Transaction Value) - We think this could be a revenue stream for those participating in the Espresso Network and [Layer-2].”

The team also plans to use ETH staking to ensure economic consistency with Ethereum Layer-1, and has currently cooperated with Eigenlayer. After launching the testnet on Polygon zkVM, Gunter noted that Espresso is also working with Caldera to build an integration between the Espresso Sequencer and the OP stack. At the same time, agreements have also been reached with teams such as Spire, Injective, and Catalyst AMM to support their priority integration with Espresso Sequencer.