BY CYNIC, Web3 RESEARCHER SOURCE: MIRROR
Introduction
There is an impossible triangle in blockchain, that is, security, decentralization, and scalability cannot be achieved at the same time. Bitcoin and Ethereum choose the former two, and the latter is poorly supported, and a large number of transactions in a short period of time can lead to network congestion and high transaction fees. The Bitcoin ecosystem first proposed the concept of scaling, hoping to build a virtual second layer on top of Bitcoin for processing transactions, and the main chain for settlement. Ethereum has tried to use State Channel, Sidechain, and Plasma to achieve expansion, but the results are not satisfactory. On September 5, 2018, Barry Hat introduced the concept of Rollup on Github. Eventually, the Rollup technology won community acceptance, with the Ethereum Foundation calling it the only Layer 2 technology. In five years, the four most concerned Rollups in the market have recently frequently reported new trends in RaaS (Rollup as a Service), and Rollup Summer has arrived.
RaaS overview
Regarding the technical analysis of Rollup, you can see the previous research report, the implementation of Rollup is more complex, the requirements for professional skills and development capabilities are high, and the high threshold of the chain is obviously contrary to the concept of blockchain permissionless. Rollup-as-a-Service (RaaS) packages Rollup as a service that provides a friendlier and easier rollup deployment experience for businesses, organizations, and individuals. Similar to what Cosmos SDK and Polkadot Substrate do for Layer1 hair chain, RaaS provides a general SDK for Rollup, which can realize independent Rollup development and deployment through simple configuration, and the customizable feature maintains the sovereignty of the project. Some RaaS projects even provide a no-code one-click chain, allowing users to deploy their own Rollups without programming skills. Rollup is highly modular, with both the Sequencer and the Proof Generator (Prover) both being upgraded for separate iterations. In RaaS, there are projects specializing in the design and development of sequencers and proof generators, which can serve all Rollups. RaaS can bring about the following changes:
- Cheaper, efficient and equally secure application chains: Rollup moves expensive computation off-chain, making transactions cheaper and more efficient; With the underlying public chain as the DA layer, which is verified by smart contracts, the same security as the underlying public chain can be obtained.
- Testing ground for innovative ideas: Rollup uses the same virtual machine environment as the underlying public chain, but the price is cheaper, and it can be used as a battle test environment for the underlying chain, and the community’s proposals will be migrated to the underlying public chain after enough testing on Rollup.
- Higher interoperability: Rollups using the same set of RaaS services, due to the same technical architecture, it is easy to define a set of message rules, without cross-chain through bridge, but directly between each Rollup to obtain high interoperability between each other.
RaaS ecology
Broadly speaking, all projects that contribute to the distribution of Rollup belong to the RaaS ecosystem. According to the principle of modularity, this paper divides the RaaS ecosystem into four levels: DA, SDK, Sequencer, and No-Code. Some of these projects offer multiple levels of service and will be addressed synthetically at first occurrence and will not be repeated below.
! [PgzcfoaHfw3750oeFXFqKB2VVcasuxLmbZM5anFA.png] (https://img.jinse.cn/7117617_watermarknone.png “7117617”)
DA data availability
Theoretically, any public chain can store Rollup’s transaction data as a DA layer, however, without a stable and properly functioning DA layer, Rollup will not be able to verify the reliability of state transitions. For Rollup, there are two options. One is Smart Contract Rollup, which is also the mode chosen by most Rollups at present, which actually relies on the settlement and data availability of the underlying public chain; The other is Sovereignty Rollup, which separates data availability from settlement, only relies on the data availability of the underlying public chain, and handles the settlement part by itself. Representatives of the former usually choose EVM-compatible, Cosmos-compatible chains, or full-featured public chains such as Solana; The latter needs have spawned projects specializing in data availability, including Celestia, EigenLayer, Avail, and others.
Celestia
Celestia is a PoS chain built using the Cosmos SDK, using a modified Tendermint consensus algorithm, using RS code for encoding block data. Using data availability sampling technology, Celestia further reduces the verification cost of light nodes, which only need to download part of the block data to verify data availability. In addition, for the detection of whether a block has been correctly encoded, Celestia uses the Optimism mechanism, that is, first optimistically believe that it is correctly encoded, and if it has not received proof of fraud for a period of time, then determine that the block has been correctly encoded. The Optimism mechanism improves runtime efficiency, but adds some latency.
Avail
Avail is a project supported by Polygon Labs, using the consensus algorithm BABE+GRANDPA, which also uses data availability sampling technology. Unlike Celestia, Avail uses proofs of validity to verify that blocks are encoded correctly, using KZG proofs, which are more efficient than Merkel Proof.
EigenLayer
EigenLayer itself is a heavily staking solution that aims to leverage the liquidity of Ethereum staking to provide economic security for the project. With EigenLayer, the new protocol does not need to build its own distributed authentication network, but only needs to leverage the security of ETH heavy staking through EigenLayer. EigenLayer works well in lightweight, permissionless, decentralized scenarios, and the best use case is in RaaS under the Ethereum scaling narrative. Since DA does not calculate transactions, but only encodes and promises transaction data, the requirements for nodes are low. Due to the use of PoS algorithm, staking liquidity is a direct reflection of blockchain security and availability, which is also the opportunity for EigenLayer to show its talents. EigenLayer exists as a smart contract on Ethereum and uses KZG proof of validity to verify that blocks are correctly encoded, however EigenLayer does not currently employ data availability sampling, which may be related to Ethereum’s next phase of the upgrade plan.
Sequencer
The job of the sequencer is to sort the received user transactions, and subsequent execution and block production will be carried out in this order. In the architecture of Ethereum, because the ordering and execution are handled by the same entity, the power of validators is too large, and there are phenomena such as MEV and censorship, which greatly affects the user experience. Separating ordering from execution is a manifestation of PBS (Propose Builder Separation) proposed to build separation ideas. However, the current Rollup architecture still relies extensively on centralized sequencers to determine the order of transactions, with a single point of failure and censorship risk, continuing with a decentralized solution.
Astria
Astra provides a solution for sharing sequencers. User transactions from different Rollups are collected into the Astria sequencer. For Rollup nodes, data can be obtained directly from Astria to obtain soft confirmation with lower latency; You can also wait for Astria to submit the data to the DA layer and get it from the DA layer to get the strongest conclusivity. Since the data submitted by Astria contains multiple Rollup transactions, for each Rollup, invalid transactions (including those from other Rollups) need to be eliminated according to the consensus mechanism before processing. Astria only provides data, and the choice of consensus is handed over to the Rollup node, ensuring the sovereignty of Rollup.
ON Stack
The default configuration of OP Stack is to use a single, dedicated orderer to handle transaction ordering, a simple modification to this is to use a licensed collection of orderers, which can reduce the possibility of ordering node evil through the PoS mechanism. After OP Stack introduced the concept of Superchain, shared sequencers became an inevitable choice. The shared sequencer brings atomic cross-chain capabilities and improves interoperability between Superchains.
Espresso
Espresso wants to take advantage of the liquidity of Ethereum stakers to gain shared security by restaking. Espresso integrates the orderer with the DA, provides the sorting results for Rollups through the REST API, masks the details of the DA, and the security of the consensus is verified by smart contracts located on L1, providing stronger reliability.
Saga
Saga started out as a similar role to the Cosmos Hub, providing shared security for application chains using the Cosmos SDK on Saga with its own set of validators. Under the hot wave of Rollup, Saga worked with Celestia, using Celestia as a DA, and Saga converted his own validator into a sequencer, using Optimistic Rollup IBC to exchange information with upper-level Rollup to provide shared security.
SOFT
Unlike other sequencers, SUAVE has always targeted the MEV market. Flashbots is the absolute leader of the MEV circuit, and SUAVE is its proposed product targeting cross-chain MEV capture, claiming “The Future of MEV is SUAVE.” Through the shared sequencer provided by SUAVE, atomic cross-chain transactions are possible, helping to improve the effectiveness of different on-chain capital markets.
EigenLayer
As mentioned earlier, EigenLayer’s use case at the DA level, and the decentralization of the orderer is also EigenLayer’s specialty. Since the orderer is only responsible for sorting and not for execution, the requirements for nodes are very low, the key to decentralization is to reduce the possibility of nodes doing evil through the penalty and confiscation mechanism, EigenLayer provides a deep staking pool, using Ethereum’s decentralization to cultivate the decentralization of the Rollup sequencer.
SDK SDK
Similar to the Cosmos SDK, the SDK provided by RaaS allows developers to reuse a large number of software modules and customize the required rollups at the lowest cost, reducing the difficulty of development.
Rollkit（Optimism）
Rollkit was originally incubated for the Celestia community and is now an independent project. Rollkit uses Celstia as the DA layer, providing an ABCI-compliant client interface upwards to serve all ABCI-compatible Rollups (Cosmos chain). At this stage, Rollkit uses a single centralized sequencer, supports the integration of the Cosmos SDK, Ethermint and CosmWasm, and users can choose their desired execution environment. In the future, Rollkit will continue to be developed to support more configuration services.
Dymension（Optimisim）
Dymension divides the service into front-end and back-end, front-end support for custom RollApps, powered by Dymension RDK (modified Cosmos SDK), back-end Dymension Hub coordinates the entire system, handles DA and sequencing. Dymension uses the Optimism mechanism, where the Dymension Hub optimistically accepts status updates from the sequencer and rolls back state changes if a valid proof of fraud is received. RollApps is capable of achieving an average latency of 0.2 seconds with a TPS of up to 20, 000. Dymension uses an elastic block generation scheme that stops block production when there are no transactions in the block, which significantly reduces the operating costs of the sequencer. At this stage, the Dymension product is still under development and already supports the execution layer of EVM, and there is no clear choice for the DA layer.
Sovereign（ZK）
The Soverign SDK provides zk-Rollup as a Service, providing a generic module for building blockchains and a zkVM that masks the details of low-level zero-knowledge proofs, allowing developers to write programs in Rust, which the SDK can compile into an efficient zk-friendly form. As the project name indicates, the Sovereign SDK emphasizes sovereignty, and Rollup determines the legitimacy of state transitions through custom consensus rules without the need for validation at the DA layer. At present, the Sovereign SDK has been adapted to Celestia and Avail in the DA layer, and supports Risc0’s zkVM, which can realize the deployment and demonstration of Rollup.
Stackr（Unknown）
Stackr proposed a more radical innovation, wanting to migrate the microservices architecture of the traditional Internet to the blockchain, and proposed the concept of micro-rollup. The relationship between regular rollups and micro-rollups is like the relationship between virtual machines and containers. With the Stackr SDK, developers only need to define the required data structures and state transition functions, and Stackr handles the rest. Stackr supports a variety of execution environments, such as EVM, Solana VM, FuelVM, etc., and users can choose the environment they want to use.
AltLayer（Optimism）
As a decentralized and elastic RaaS, AltLayer provides a developer-oriented SDK and a No-Code Dashboard that requires no code experience, which can realize one-click chaining. AltLayer provides a unique elastic Rollup, called Flash Layer. When application demand surges, a Rollup chain can be quickly deployed, and when the demand returns to normal, settlement is carried out on L1, and the Rollup is abandoned, realizing the common horizontal expansion in the Internet system. AltLayer’s goal is to support multi-chain, multi-execution environments, and support for EVM and WASM has been implemented.
OP Stack（Optimism）
The OP Stack is built to support the Optimism Superchain, a proposed network where L2 networks share security, communication layers, and co-development stacks. After the Bedrock upgrade, Rollup, created using OP Stack, will be natively compatible with Superchain. Of course, the components of the OP Stack can also be modified to obtain customized features, base and opBNB are Rollups developed based on OP Stack. The security and usability of OP Stack have been fully tested by OP Mainnet, base and other chains, but there are still problems such as lack of fraud proof and centralized sequencers, and OP Stack is exploring new ways out, such as adopting cheaper DA layers, using ZK Proof, sharing sequencers, etc.
Arbitrum Orbit（Optimism）
On June 22, Offchain Labs released a tool for issuing Arbitrum Orbit Chain. Orbit Chain is Layer 3 on top of Arbitrum Layer 2, and you can choose to settle using one of three Layers 2, including Arbitrum One, Arbitrum Nova, and Arbitrum Goerli. Users can choose to use Rollup or Anytrust technology, the difference is that Anytrust uses DACs instead of submitting transaction data to the chain, which is cheaper but slightly less secure. The advantages of Orbit Chain are its simple hairchain process, interoperability with the Arbitrum ecosystem, instant updates to Nitro, and EVM+ compatibility provided by Stylus (supporting Rust, C, C++ and running in the WASM virtual machine). Users do not need to customize the distribution of any Orbit Chain, but they must settle on Arbitrum Layer 2, otherwise they will need to contact Offchain Labs or Arbitrum DAO for authorization.
ZK Stack（ZK）
On June 26, zkSync published an article announcing that it would modify the existing open source code in the coming weeks to launch ZK Stack, which allows users to build their own ZK superchains using its customization. Unlike Arbitrum’s Orbit Chain, ZK Stack emphasizes sovereignty and interoperability, users can fully customize according to their needs, and chains built using ZK Stack can achieve bridgeless interoperability. ZK Stack can be used to build both Layer 2 and Layer 3, and there is no official restriction on it, and there is no requirement to settle on zkSync. From this point of view, the sovereignty offered by ZK Stack seems stronger.
Starknet Stack/Madara（ZK）
Madara’s initial positioning was the sequencer on Starknet, and with the help of technology accumulation, it successfully developed the Starknet Stack on the basis of the original product to help build the application chain Rollup on Starknet. With Ethereum as the DA layer, settlement is carried out on Starknet with the help of Starknet’s shared proof. From a usability perspective, Madara has helped the team launch the application chain Rollup in PragmaOracle hackathon within 24 hours, and gave a video demonstration, which is more complete than the zkSync team’s ZK Stack.
No-Code
No-code deployment is a solution with a lower threshold, providing non-developers with the option of one-click chaining, which is expected to further increase adoption.
Caldera（Optimism）
Calera Chain is a full-link customized one-click chain solution. At the execution layer, OP Stack and Arbitrum Orbit are supported, the settlement layer can select EVM-compatible chains such as Polygon, BSC, and Evmos, and the DA layer is supported by EigenLayer and Celestia. In addition to the Rollup chain itself, Caldera also provides a series of supporting infrastructure, such as blockchain explorers, testnet faucets, oracles, Hyperlane-supported bridges, etc., to further reduce the cost of sending chains.
Eclipse（Optimism+ZK）
Eclipse has high customizability capabilities, supporting EVM and SolanaVM at the execution layer, Celestia, Avail, and EigenLayers at the DA layer, providing Optimistic settlement at the settlement layer, and is developing RISC0 zkVM that supports ZK settlement. Users can also choose the access of the chain (permissioned/permissionless), gas token, and whether to charge gas fees, whether MEVs are allowed, specific Opcodes, block sizes, etc. as needed, giving a high degree of flexibility.
Opside（ZK）
Opside’s biggest feature is that it builds a decentralized ZKP marketplace. Originally, I wanted to describe Prover as a separate layer, but I abandoned it due to the small number of projects. Zero-knowledge proof ZKP has high requirements for computing power, and in the context of the gradual increase in the market share of zkRollup, the decentralization of ZKP is the general direction of future development. Opside adopts a permissionless PoW consensus mechanism to attract miners to generate ZKP and maintain the security and availability of zkRollup, without the need for the issuer to consider the generation problem of proof. At the validator level, the PoS mechanism is adopted to lower the threshold for participation and promote the centralization of validators. Opside provides customized services, users can choose from zkEVMs such as zkSync, Starknet, Polygon zkEVM, etc., and can also modify the economic model and adjust gas fees.
The future of RaaS
More ZK
Compared with Optimistic Rollup, zkRollup upgrades from economic security to cryptography security with a higher degree of security. No more waiting for a long challenger and lower confirmation delay; The data is more compressed and DA is cheaper. Although the Optimism solution has a high market share in the early stage of product launch due to its high technological maturity, ZK will play an even more important role as a revolutionary technology in the future. Vitalik put ZK technology and blockchain technology in the same important position as blockchain technology in Montenegro, which also reflected the importance of ZK. With the continuous improvement of technology, more zk-rollup as a service projects will enter the public field of vision and provide users with more choices.
More non-Ethereum
Today, the Ethereum ecosystem still dominates the entire blockchain industry. Although other communities continue to iterate and innovate, they still cannot shake the throne of the Ethereum ecosystem. In RaaS, things seem to have changed a bit. With the low capacity and high price of data storage on Ethereum, people can choose cheaper DA layers such as Celestia, Avail or Polygon; Ethereum is non-modular, it is very complicated to modify, and one can choose the highly modular Cosmos SKD; EVM execution is inefficient, and people can choose Solana VM, Move VM, CairoVM with higher efficiency. A single branch is not spring, and a hundred flowers bloom in the spring garden. Various solutions from the non-Ethereum ecosystem will bloom new vitality in RaaS.
More modularity
The role of modularity can be divided into two points, one is that each module can be quickly iterated separately to improve development efficiency; Second, modularity can greatly reduce the complexity of customization. In the current market environment, it is almost impossible to independently develop a one-stop solution, and the overall innovation speed will never be able to catch up with the rapid iteration of small modules. The extreme requirements for customization will lead to further refinement of the module division, and if it is not modularized, it will eventually be split by other projects, such as OP Stack and Arbitrum Orbit separated from the execution layer by Caldera.
More customization
When the expansion technology gradually matures, the transaction cost is getting lower and lower, and the infrastructure is perfect, people react, “fool, the key is in the application”. Each application has its own specific operating rules and modes, and a single solution cannot adapt to a complex application ecology, so we need more customization.
From block size to data structure, from transaction fees to transaction latency, from admission mechanism to security assumptions, from contract engine to token empowerment, Rollup will be gradually customized in the future to provide more flexible solutions for applications.
More interoperability
As mentioned earlier, the Ethereum ecosystem occupies the dominant position of the blockchain ecology, which actually has a lot to do with the huge liquidity it locks. In the crypto market, because each chain exists independently, liquidity cannot exist in two chains at the same time, and the increase in the number of rollups will lead to further division of liquidity, and liquidity has become a very serious problem.
Stronger interoperability can reduce cross-chain friction, make liquidity smoother and travel between different chains, and can even be called shared liquidity. In line with the ideas advocated by Cosmos, OP Stack, Arbitrun Orbit, ZK Stack, Starknet Stack and other projects are trying to build a huge application chain ecology, using the same technology stack to build Rollup, because of its same technical architecture, so it can obtain native interoperability, without the need to build cross-chain bridges.
More heavy staking
At present, many services in RaaS adopt the PoS model, using economic penalties to increase the cost of evil and improve security. However, economic security requires deep collateral of pledged assets, resulting in low capital utilization and increased start-up costs for service providers.
Re-staking can be a good solution, leveraging the huge pool of Ethereum consensus staking to provide shared security for other services through re-staking, while increasing revenue and capital utilization for stakers. At present, EigenLayer and Espresso are working on related work, and it is foreseeable that more services will be heavily staked to ensure economic security in the future.
- RaaS, the biggest benefit is actually the application chain. Can the application chain concept proposed by Cosmos and Polkadot in the early years sprout new shoots and achieve an outbreak in the RaaS ecosystem? Perhaps, only innovation at the application layer can drive the explosion of the RaaS ecosystem. After all, no matter how good a road is, you have to have cars running on it to be considered infrastructure. *
