This article is translated from Thor Hartvigsen
Preface
As the Ethereum upgrade time gets closer and closer, discussions related to the Ethereum ecology are becoming more and more popular, and even several expansion plans are taking advantage of this time to release news, whether it is Arbitrum’s various activities, Optimism’s second round of airdrops, zkSync's hints about the imminent currency issuance, etc., have made the currency and chain circles agitated; while Polygon began to announce a series of exciting cooperation at the end of last year.
This article focuses on the current development of the above four expansion plans on Ethereum and understands what their future roadmaps want to do. Let yourself know more about the current development trends of blockchain!
Statement: This article has been authorized by the original author, Thor Hartvigsen
Article content
important terms
First, define the modularity of the blockchain. The blockchain can be divided into 4 parts. Current blockchains (Ethereum, Solana, etc.) are monolithic, meaning a single layer handles all parts. Modular blockchains are chains that outsource one or more of these layers to external chains.
Ethereum Rollups (Layer 2) is a separate blockchain that extends and inherits the security of Ethereum. Rollups such as Arbitrum and Optimism are the execution layer and inherit data availability, consensus and settlement from the Eth-mainnet.
Rollups come in two types:
Optimism Rollups: Using Fraud Proofs (Arbitrum and Optimism)
ZK Rollups: Using Proof of Validity (zkSync, Starknet, zk-EVM's)
Fraud Proof: Information is exchanged between "Prover" and "Verifier". All transactions are assumed to be valid and added to the batch file of transactions, which are then reviewed by "Watchers" to ensure that no malicious behavior has occurred.
Validity Proof: Validity Proof is calculated on Rollups rather than on the Ethereum mainnet (as opposed to Fraud Proof). The "certifier" and "verifier" rely on cryptography to exchange information. The information is shared with each other but will not be disclosed.
Supplement: Another key point of Rollups is the sequencer: the sequencer is a designated node responsible for submitting user transactions to Layer 2. Further publish the Rollups transaction package to the Ethereum mainnet to update the Rollups status.
💙 Decision
Currently, Arbitrum uses the following methods:
A single centralized sequencer is responsible for receiving user transactions and sending transaction batches back to the main network.
A set of "whitelists" are used to assist the Arbitrum validator in reading the transaction batches of the sequencer and submitting the "Arbitrum state-root" to the Ethereum mainnet in the form of a fraud proof. Any validator can challenge the "state-root" settled on the mainnet. As long as there is an honest validator, the correct Layer 2 state will be published on the mainnet.
There have been concerns before about validators being whitelisted. However, since the completion of Ethereum Merge, if no validator submits "state-root" within 7 days, the whitelist function will be ignored, which significantly improves security. If you want to know more, you can refer to this article:
https://twitter.com/bkiepuszewski/status/1594754717330309120
route map:
Arbitrum deployed Nitro in 2022, which significantly reduced communication and execution costs.
In the future, batch sequencing will be managed by a committee of sequencers rather than being handled centrally.
Arbitrum may launch a token to improve network security.
🔴 Optimism
Optimism also runs a centralized sequencer and uses special permissions to sequence transactions and submit transaction batch files.
Meanwhile, the Optimism team is developing their interactive fraud proof system to ensure the correctness of the rollups state.
Therefore, the current fraud proof mechanism has been temporarily disabled, and users can only rely on the sequencer to publish valid rollups state to the Ethereum mainnet.
However, all of this is about to change with "OP Stack". Optimism is more than just Layer 2 Optimism Rollups on Ethereum.
OP Stack is: “A modular open source blueprint for a variety of highly scalable and interoperable blockchains, not just Rollups, not just Optimism.”
Essentially, OP Stack is a framework for building blockchains and Rollups.
Developers can combine one or more modules in the OP Stack to build interoperable chains. These will be called "OP-chains" and can be Layer 2, Layer 3, or something completely different.
OP Stack will introduce a decentralized set of sequencers, and OP-chains can integrate these sequencers so that there is no need to worry about the block production of the respective chains. It also allows the introduction of higher-level and interoperable "atomic cross-chain composability".
The first step in this ambitious roadmap is Optimism Bedrock, which will enable:
Ethereum equivalence
Lower Gas Fee
Modularity: Prepare for the future by being able to replace OP Stack components. Optimism can technically become ZK-Rollup
🟣 Polygon
Although Polygon originated from Layer 2, as it continues to develop, it is essentially more similar to EVM Layer 1. The PoS mechanism that comes with Polygon is just one of its many future developments.
Polygon is building four different chains, all with zero-knowledge structures (using proofs of validity).
One of them is Polygon Hermez, which is a zk-EVM. zk-EVM can be divided into four categories based on Ethereum compatibility and performance. Polygon's zk-EVM is type 2.
Type 2 is significantly more compatible with Ethereum than Type 4, but is not as performant as Type 4. Polygon Hermez is said to be just around the corner.
Polygon’s other zk products include:
Miden (STARK based Rollups)
Zero (custom proof technology)
Nightfall (privacy-focused Rollups)
Polygon is also building a modular blockchain called Avail. It is similar to Celestia in the sense that it acts as a data availability layer.
Last year, the author also made a complete summary of the development of Polygon. You can refer to this article:
https://twitter.com/ThorHartvigsen/status/1580225764984659969
🔁 zkSync
Matter Labs is building zkSync 2.0, a type 4 zk-EVM. According to the project’s recent interesting hints on Twitter, the mainnet launch will have a chance to be implemented in the near future. Since this is a type 4 zk-EVM, it has more High performance and scalability, but poor compatibility with Ethereum.
In theory, lower compatibility makes it more difficult to implement from a developer perspective and challenging for Ethereum DApps to deploy here.
However, zkSync has built multiple solutions to solve this problem, including their own virtual machine and language.
zkSync 2.0 will be split into two interoperable chains (zkRollup and zkPorter). zkPorter is a "will", closer to Layer 3, with "off-chain data availability" (data is processed on Layer 2 zk-Rollup).
It is also because of this design that zkPorter is said to be able to provide more than 20,000 TPS. However, the security of Layer 3 is slightly lower than that of Layer 2. The advantage is that it is better in terms of scalability.
For example, Uniswap deploys their smart contracts on Layer 2, and DApp users can complete transactions through zkPorter (Layer 3) at very low fees.
For more information about Layer 3, please refer to this article:
https://twitter.com/ThorHartvigsen/status/1601925264656588800
The final piece of the zkSync plan is the so-called "HyperChains", a Layer 3 built on and supported by the Layer 2 zk-EVM. These HyperChains serve as "Validiums" and have higher scalability and customization (such as application chains), but are slightly less secure than the Ethereum mainnet.
in conclusion
In fact, there are many interesting projects in the Layer 2 expansion plan, such as Celestia and Fuel mentioned before when talking about modular blockchain, and Scroll and Starknet, which many people have discussed recently, are worthy of attention. From the above article, we can It can be seen that the biggest problems with past expansion plans are "centralization" and "defects". This has also caused many doubts in the development of the project, and is even considered to be inconsistent with the core value of the blockchain. And we have also seen that the four Layer projects in this article are indeed actively improving these problems and providing better applications and services.
It just so happens that I have actually operated all of these four Layer 2s. Most people should have used Polygon, so I won’t mention it in particular. For the other three, it is obvious in terms of operating experience, transaction speed and transaction cost. It is better than the Ethereum mainnet, and I can even say that it is better than the online banking operations that most of us are used to. This also makes me more optimistic and confident about the development of blockchain.
Of course, if there are advantages to the development of an industry, there must also be disadvantages. Perhaps the most criticized thing is security. Compared with the Ethereum main network, Layer 2 may be more susceptible to hacker attacks, causing risks and losses. This must be paid special attention to. , coupled with the lack of coordination between Layer 2, the possibility of interoperability is too low, which also makes developers face more challenges in development.
However, this does not affect the vigorous development of Layer 2. It has indeed solved many of the pain points faced by Ethereum in the past. In the future, as long as the aforementioned shortcomings can be adjusted and optimized, I believe this ecosystem will get better and better.
References
Thor Hartvigsen《Layer 2 roadmaps》
https://pine-ixora-306.notion.site/Layer-2-roadmaps-85b41e16e8424bab85061251e0dfaa61
Decision
https://arbitrum.io/
Optimism
https://community.optimism.io/docs/protocol/
Polygon
https://wiki.polygon.technology/
zkSync
https://docs.zksync.io/zkevm/#how-scalable-is-a-zk-rollup
Thor Hartvigsen《A thread breaking down the basics of scaling》
https://twitter.com/ThorHartvigsen/status/1601925174898659328
Thor Hartvigsen《A thread breaking down modular blockchains and Celestia + Fuel》
https://twitter.com/ThorHartvigsen/status/1613579112534396928
Chinese translation: https://mirror.xyz/lilcrowz.eth/QwhOFq9n39tjmFXdtYxm1QzyGcC4cWAbigtIQZvyz84
