Author: 1912212.eth, Foresight News
With the growing maturity of the Ethereum Layer 2 network and the significant reduction in gas fees, these networks are showing a trend of vigorous growth. However, accompanying problems have emerged, such as fees and speed being affected by various factors, leading to subpar user experience. In this context, the importance of transaction ordering is increasingly highlighted as a key factor in resolving transaction bottlenecks and optimizing user experience.
In April of this year, Astria, a modular blockchain focusing on shared sequencers, completed a $5.5 million seed round of financing, led by Maven 11 with participation from 1kx, Delphi Ventures, Robot Ventures, among others. Just 3 months later, Astria completed another $12.5 million in financing, with dba and Placeholder VC leading the round and Hasu among the participants.
What is Astria?
Astria is developing a decentralized shared sequencer network aimed at providing fast finality, censorship resistance, composability, and decentralization for Rollups.
Currently, running a centralized sequencer on L2 is more convenient, cheaper, and easier for users to use, so mainstream L2s are managed by their own teams. Although L2 users can submit transactions directly to L1 to bypass the sequencer, users must pay transaction gas fees to L1, and transactions may take longer to complete.
Sequencers control the order of transactions and theoretically have the right not to include user transactions. Sequencers can also extract MEV from transaction groups. If there is only one sequencer, the centralization risk increases. Therefore, a decentralized shared sequencer still has its significance.
How Astria Operates
Astria’s decentralized sequencer has multiple sequencer nodes to order Rollup transactions. In Astria’s operating model, users submit transactions to Rollups, which automatically enter their respective Rollup node memory pools, with the aggregator responsible for collecting txns and sending them to the sequencer. Finally, the sequencer consolidates the txns into a shared block and sends pre-confirmations to users.
Current sequencers are based on specific Rollups. Astria, on the other hand, processes blocks for multiple Rollups in batch. Through data compression, more costs can be saved when publishing data to L1. The decentralized shared sequencer network incentivizes participants from multiple Rollup ecosystems to act as validators on the network.
Astria Stack
Astria’s main components include 5 parts: aggregator, sequencer, relayer, DA, and scheduler.
Aggregator
Technical professionals may be able to directly use the sequencer for better transaction ordering, but for the majority of ordinary users, it would increase complexity. Direct interaction with the sequencer requires users to hold sequencer tokens and maintain a sequencer wallet, both of which negatively impact the user experience.
Astria provides an aggregator for users to abstract this complexity. The aggregator acts as a gas station, covering the cost of user transaction ordering. The aggregator also provides users with an unordered guarantee, bundling transactions in the order they are received.
Sequencer
Astria’s sequencer layer uses CometBFT as its consensus algorithm. Chains supporting CometBFT can support IBC (Inter-Blockchain Communication), meaning they can operate across many other chains.
The uniqueness of Astria’s sequencer lies in the fact that the transactions it contains are not executed (delayed sequencing) but are assigned to another execution engine, Rollup. Sequencer nodes can choose to act as “validators,” meaning they actively participate in the production and finality of new blocks.
The application logic of Astria’s sequencer allows for three main functions: sorting of Rollup data, value transfer, and changes in the validator set.
Relayer
The relayer’s function is to obtain validated blocks from the sequencers and pass them to the DA layer. Since the sequencer’s block time is faster than the DA’s, the relayer batch processes ordered data from multiple sequencer blocks, compresses them, and submits them to the DA.
Individual sequencer blocks can also be obtained by the scheduler before being submitted to the DA. This enables quick finality of improved user experience, acting as a soft commit for the execution layer. The data set sent from the relayer to the DA layer is used as a factual source and ultimately extracted from the DA for finality confirmation in Rollup.
DA
Astria uses Celestia as the data availability layer, the final destination for all data ordered by the sequencer network. Once data is written to Celestia, transaction order is considered final, and when a new Rollup node starts, all data is extracted from there.
Scheduler
The scheduler can be seen as the consensus implementation of the Rollup full node, similar to the operation node in the OP Stack. The scheduler is the corresponding part of the execution engine, together forming a complete Rollup node. Its role is to extract transactions belonging to the Rollup node from each sequencer block, forward them to the execution layer, and connect the sequencer and DA layers to the Rollup execution layer.