From the perspective of RaaS overview, ecology and future prospects, do you think Rollup summer is coming?

Author: Cynic Leo; Source: LK Venture

TL;DR

There is an impossible triangle in the blockchain, that is, security, decentralization and scalability cannot be achieved at the same time. Bitcoin and Ethereum chose the former two, but lacked support for the latter. A large number of transactions in a short period of time will lead to network congestion and high transaction fees.

The Bitcoin ecosystem first proposed the concept of expansion, hoping to build a virtual second layer on top of Bitcoin for processing transactions, while the main chain is used for settlement. Ethereum has successively tried to use State Channel, Sidechain, and Plasma to achieve expansion, but the results have been unsatisfactory. On September 5, 2018, Barry Hat proposed the concept of Rollup on Github. In the end, Rollup technology won the recognition of the community, and the Ethereum Foundation called it the only Layer 2 technology.

Five years have passed in a blink of an eye. Ethereum Rollup, which has received the most attention in the market, has frequently reported new trends in RaaS (Rollup as a Service). Will we soon have a summer for Rollup? This article analyzes the overview, ecology and future development of RaaS, hoping to gain a glimpse from point to line, and from line to surface.

RaaS Overview

Regarding the technical analysis of Rollup, the implementation of Rollup is relatively complex and requires high professional skills and development capabilities. The high threshold for launching a chain obviously runs counter to the permissionless concept of blockchain.

Rollup-as-a-Service (RaaS) packages Rollup as a service to provide enterprises, organizations and individuals with a more friendly and simple Rollup deployment experience. Similar to Cosmos SDK and Polkadot Substrate.

As Layer 1 does when launching a chain, RaaS provides a universal SDK for Rollup. Through simple configuration, independent Rollup development and deployment can be achieved. The customizable features maintain the sovereignty of the project. Some RaaS projects even provide a code-free one-click chaining function, allowing users to deploy their own Rollups without having programming skills.

Rollup is highly modular, and both the sequencer (Sequencer) and the proof generator (Prover) can be independently iteratively upgraded. In RaaS, there are projects specializing in the design and development of sequencers and proof generators, which can provide services for all Rollups.

RaaS can bring the following changes:

1. Cheaper, efficient and equally secure application chain: Rollup moves the expensive calculation process off-chain, making transactions cheaper and more efficient; using the underlying public chain as the DA layer, verified by smart contracts, it can obtain the same The same security as the public chain.

2. A testing ground for innovative ideas: Rollup uses the same virtual machine environment as the underlying public chain, but is more affordable. It can be used as a battle test environment for the underlying chain. Community proposals will be migrated after sufficient testing on Rollup. to the underlying public chain.

3. Higher interoperability: Rollups using the same set of RaaS services have the same technical architecture, so it is easy to define a set of message rules. There is no need to cross-chain through bridging. Instead, messages are transferred directly between each Rollup to obtain High interoperability with each other.

RaaS Ecosystem

Broadly speaking, all projects that contribute to the release of Rollup belong to the RaaS ecosystem. Based on the principle of modularity, this article divides the RaaS ecosystem from bottom to top into four levels: DA (data availability), SDK (software development kit), Sequencer (sequencer), and No-Code (no-code deployment).

Some of these projects provide multiple levels of services, which will be discussed comprehensively when they first appear and will not be repeated below.

2.1 DA (Data Availability)

Theoretically, any public chain can serve as a DA layer to store Rollup's transaction data. However, without a stable and correctly operating DA layer, Rollup will be unable 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 current rollups, and actually relies on the settlement and data availability of the underlying public chain; the other is Sovereignty Rollup, which separates data availability and settlement and only relies on the data availability of the underlying public chain. Handle the billing part yourself.

Representatives of the former usually choose EVM-compatible, Cosmos-compatible chains or public chains with complete functions such as Solana; the needs of the latter have spawned projects specializing in data availability, including Celestia, EigenLayer, Avail, etc.

Celestia

Celestia is a PoS chain built using the Cosmos SDK, uses a modified Tendermint consensus algorithm, and uses RS code to encode block data. Using data availability sampling technology, Celestia further reduces the verification cost of light nodes. Light nodes only need to download part of the block data to verify data availability.

In addition, for the detection of whether the block is correctly encoded, Celestia uses the Optimism mechanism, that is, first optimistically believes that it is correctly encoded, and if a fraud certificate is not received for a period of time, it is determined that the block has been correctly encoded. The Optimism mechanism improves runtime efficiency, but increases some latency.

Avail

Avail is a project supported by Polygon Labs. The consensus algorithm used is BABE+GRANDPA, and it also uses data availability sampling technology. Unlike Celestia, Avail uses validity proofs to verify that blocks are correctly encoded, using a KZG proof that is more efficient than Merkel Proof.

OwnLayer

EigenLayer itself is a heavy-staking solution, aiming to use the liquidity of Ethereum pledges to provide economic security for projects. With EigenLayer, the new protocol does not need to build its own distributed verification network, but only needs to take advantage of the security of ETH heavy pledge through EigenLayer. EigenLayer can be used excellently in lightweight, permissionless, decentralized scenarios. Under the narrative of Ethereum expansion, the best use case is in RaaS.

Since DA does not calculate transactions and only encodes and commits transaction data, it has lower requirements for nodes. Due to the adoption of the PoS algorithm, pledge liquidity is a direct reflection of the security and availability of the blockchain. This is also an opportunity for EigenLayer to show its talents.

EigenLayer exists as a smart contract on Ethereum and uses KZG validity proof to verify the correct encoding of blocks. However, currently EigenLayer has not yet adopted data availability sampling technology, which may be related to the next phase of Ethereum's upgrade plan.

2.2 Sequencer

The job of the sequencer is to sort the received user transactions, and subsequent execution and block generation will be carried out in this order. In the Ethereum architecture, since sorting and execution are handled by the same entity, the verifier has too much power, and phenomena such as MEV and censorship exist, which greatly affects the user experience.

Separating sorting and execution is a manifestation of the idea of building separation proposed by PBS (Propose Builder Separation). However, the current Rollup architecture still relies extensively on a centralized sequencer to determine the order of transactions. There is a single point of failure and risk of censorship. A decentralized solution is required.

Astria

Astra provides a shared sorter solution. User transactions from different Rollups will be collected into the Astria sorter. For Rollup nodes, you can directly obtain data from Astria to obtain soft confirmation with lower latency; you can also wait for Astria to submit the data to the DA layer and obtain it from the DA layer to obtain the strongest final confirmation.

Since the data submitted by Astria contains transactions from multiple rollups, 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 leaves the consensus choice to Rollup nodes, ensuring the sovereignty of Rollup.

UP STACK

The default configuration of OP Stack is to use a single dedicated sequencer to handle transaction sorting. A simple modification to this is to use a permissioned sequencer set, which can reduce the possibility of evildoing by sequencer nodes 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 functionality and improves interoperability between Superchains.

Espresso

Espresso hopes to leverage the liquidity of Ethereum stakers to gain shared security through heavy staking. Espresso integrates the sorter and DA, providing sorting results for Rollups through the REST API, shielding the details of DA. The security of the consensus is verified by the smart contract located on L1, providing stronger reliability.

Saga

Saga originally served as a Cosmos Hub-like role, using its own set of validators to provide shared security for application chains using the Cosmos SDK on Saga.

Under the hot wave of Rollup, Saga cooperated with Celestia, using Celestia as DA. Saga converted its own validator into a sequencer, and used Optimistic Rollup IBC to exchange information with the upper-layer Rollup to provide shared security.

SUAVE

Unlike other sequencers, SUAVE has always targeted the MEV market. Flashbots is the absolute leader in the MEV track, and SUAVE is its product aimed at cross-chain MEV capture. It claims that "The Future of MEV is SUAVE." Through the shared sequencer provided by SUAVE, atomic cross-chain transactions become possible, and there are Help improve the effectiveness of capital markets on different chains.

OwnLayer

As mentioned earlier, EigenLayer's use cases at the DA level are also EigenLayer's specialty, as is the decentralization of sorters.

Since the sorter is only responsible for sorting but not execution, the requirements for nodes are very low. The key to decentralization is to reduce the possibility of nodes doing evil through the penalty mechanism. EigenLayer provides a deep pledge pool and uses the decentralization of Ethereum to cultivate Rollup Decentralization of sorters.

2.3 SDK (Software Development Kit)

Similar to the Cosmos SDK, the SDK provided by RaaS allows developers to reuse a large number of software modules and customize the required Rollup at the lowest cost, reducing the difficulty of development.

Rollkit（Optimism）

Rollkit was originally incubated by the Celestia community and has now become an independent project. Rollkit uses Celstia as the DA layer to provide an ABCI-compatible client interface upwards to provide services for all ABCI-compatible Rollups (Cosmos chain).

At this stage, Rollkit uses a single centralized sequencer and supports the integration of Cosmos SDK, Ethermint and CosmWasm. Users can choose the execution environment they want. 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. The front-end supports customized RollApps and is supported by Dymension RDK (modified Cosmos SDK). The back-end Dymension Hub coordinates the entire system and handles DA and sorting.

Dymension uses the Optimism mechanism. Dymension Hub first optimistically accepts status updates from the sequencer. If a valid fraud proof is received, the status modification will be rolled back. RollApps is able to achieve an average latency of 0.2 seconds and a maximum TPS of 20,000.

Dymension adopts a flexible block production scheme. When there are no transactions in the block, it will stop producing blocks, which significantly reduces the operating costs of the sequencer.

At this stage, Dymension products are still under development and already support the execution layer of EVM. There is no clear choice for the DA layer.

Sovereign（ZK）

Soverign SDK provides zk-Rollup as a Service, which provides a common module for building a blockchain and a zkVM that shields the details of the underlying zero-knowledge proof, allowing developers to write programs in Rust, and the SDK can compile them into efficient zk Friendly form.

As the project name indicates, Sovereign SDK emphasizes sovereignty, and Rollup determines the legality of state transitions through customized consensus rules without requiring verification by the DA layer.

Currently, Sovereign SDK has been adapted to Celestia and Avail at the DA layer, supports Risc0's zkVM, and can implement Rollup deployment and demonstration.

Stackr（Unknown）

Stackr proposed a more radical innovation, wanting to migrate the microservice architecture in the traditional Internet to the blockchain and proposed the concept of micro-rollup.

The relationship between regular rollup and micro-rollup is like the relationship between virtual machines and containers. Using the Stackr SDK, developers only need to define the required data structures and state transfer functions, and Stackr handles the rest.

Stackr supports multiple execution environments, such as EVM, Solana VM, FuelVM, etc. Users can choose the environment they want to use.

AltLayer（Optimism）

As a decentralized and flexible RaaS, AltLayer provides an SDK for developers and a No-Code Dashboard that requires no coding experience, enabling one-click chain publishing.

AltLayer provides a unique flexible Rollup called Flash Layer. When application demand surges, a rollup chain can be quickly deployed. When the demand returns to normal, settlement is performed on L1 and the rollup is discarded, achieving horizontal expansion common in the Internet system.

AltLayer's goal is to support multi-chain and multi-execution environments, and currently supports EVM and WASM.

OP Stack（Optimism）

OP Stack is built to support Optimism Superchain, a proposed network of L2 networks sharing security, communication layers and co-development stacks. After the Bedrock upgrade, Rollups created using OP Stack will be natively compatible with Superchain. Of course, you can also modify the components of OP Stack to obtain customized features. Base and opBNB are all Rollups developed based on OP Stack.

The security and usability of OP Stack have been fully tested by OP Mainnet, base and other chains. However, there are still problems such as lack of fraud proof and sorter centralization. OP Stack is exploring new ways out, such as using a cheaper DA layer. , use ZK Proof, shared sorter, etc.

Decision Orbit（Optimism）

On June 22, Offchain Labs released tools for issuing Arbitrum Orbit Chain. Orbit Chain is Layer 3 on top of Arbitrum Layer 2. You can choose to use one of the three Layer 2s including Arbitrum One, Arbitrum Nova, and Arbitrum Goerli for settlement. Users can choose to use Rollup or Anytrust technology. The difference is that Anytrust uses DAC instead of submitting transaction data to the chain, which is cheaper but less secure. The advantages of Orbit Chain lie in its simple chain issuance process, interoperability with the Arbitrum ecosystem, instant updates of Nitro, and EVM+ compatibility provided by Stylus (supports writing in Rust, C, C++, and runs on the WASM virtual machine). Users can freely customize the issuance of any Orbit Chain, but it must be settled on Arbitrum Layer2, otherwise they need to contact Offchain Labs or Arbitrum DAO to obtain authorization.

ZK Stack（ZK）

On June 26, zkSync published an article claiming that it would modify the existing open source code in the next few weeks and launch ZK Stack, allowing users to use its customization to build their own ZK super chain. Different from Arbitrum's Orbit Chain, ZK Stack emphasizes sovereignty and interoperability. Users can fully customize according to their needs. Chains built using ZK Stack can achieve bridgeless interoperability. ZK Stack can be used to build both Layer 2 and Layer 3. There is no official restriction on it and there is no requirement to settle on zkSync. From this point of view, the sovereignty provided by ZK Stack seems to be stronger.

Starknet Stack/Madara（ZK）

Madara was originally positioned as a sequencer on Starknet. With the help of technology accumulation, it successfully developed Starknet Stack based on the original product to help build the application chain Rollup on Starknet. Ethereum is used as the DA layer, and settlement is carried out on Starknet with the help of Starknet's shared prover. From a usability perspective, Madara has helped the team implement the release of the application chain Rollup within 24 hours in the PragmaOracle hackathon and provided a video demonstration. Compared with the ZK Stack of the zkSync team, the degree of completion is higher.

2.4 No-Code (no code deployment)

Codeless deployment is a solution with a lower threshold and provides non-developers with the option of one-click link publishing, which is expected to further increase adoption.

Caldera（Optimism）

Calera Chain is a full-link customized one-click chaining solution. At the execution layer, OP Stack and Arbitrum Orbit are supported. The settlement layer can choose EVM compatible chains such as Polygon, BSC, and Evmos. 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 browsers, testnet faucets, oracles, bridges supported by Hyperlane, etc., to further reduce the cost of chain issuance.

Eclipse（Optimism+ZK）

Eclipse has high customization capabilities. It supports EVM and SolanaVM at the execution layer, and is connected to Celestia, Avail, and EigenLayer at the DA layer. The settlement layer provides Optimistic settlement, and is developing RISC0 zkVM that supports ZK settlement.

Users can also choose the chain's access (permission/unpermission), Gas token, whether to charge Gas Fee, whether to allow MEV, specific Opcode, block size, etc., according to their needs, which gives them a high degree of flexibility.

Opside（ZK）

The biggest feature of Opside is that it has built a decentralized ZKP market. I originally wanted to describe Prover as a separate layer, but gave up due to the small number of projects. Zero-knowledge proof ZKP has high requirements for computing power. In the context of the gradual increase in zkRollup's market share, the decentralization of ZKP is the general direction of future development.

Opside uses a permissionless PoW consensus mechanism to attract miners to generate ZKP and maintain the security and availability of zkRollup, without the chain issuer having to consider the generation of proofs. At the verifier level, the PoS mechanism is adopted to lower the participation threshold and promote the centralization of verifiers.

Opside provides customized services. Users can choose from zkSync, Starknet, Polygon zkEVM and other zkEVMs, and can also modify the economic model and adjust Gas costs.

Future Development of RaaS

MoreZK

Compared with Optimistic Rollup, zkRollup has upgraded from economic security to cryptography security, with a higher degree of security; there is no longer a need to wait for a long challenger, and the confirmation delay is lower; the degree of data compression is higher, DA cheaper.

Although the Optimism solution has taken advantage of its early advantage in product release to occupy a high market share due to its high technological maturity, ZK, as a revolutionary technology, will play a more important role in the future. In his speech in Montenegro, Vitalik placed ZK technology and blockchain technology in an equally important position, which also reflected the importance of ZK.

As technology continues to improve, more zk-Rollup as a Service projects will enter the public eye and provide users with more choices.

More Non-Ethereum

To this day, the Ethereum ecosystem still occupies an absolutely dominant position in 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. Due to 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 and very complex to modify, so people can choose the highly modular Cosmos SKD ; The execution efficiency of EVM is low, people can choose Solana VM, Move VM, CairoVM which are more efficient.

One branch blooming alone is not spring, but a hundred flowers blooming together fill the garden. Various solutions in the non-Ethereum ecosystem will bloom new vitality in RaaS.

More Modularity

The role of modularization can be divided into two points. First, each module can be independently and quickly iterated 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. The overall innovation speed can never keep up with the rapid iteration of small modules. The extreme requirements for customization will lead to further refinement of module division. If it is not modularized, it will eventually be split by other projects. For example, OP Stack and Arbitrum Orbit were separated into execution layers by Caldera.

More customization

When the expansion technology gradually matures, transaction costs become lower and lower, and the infrastructure is improved, people will react and say, "Fool, the key lies in application." Each application has its own specific operating rules and modes. A single solution cannot adapt to the complex application ecosystem, so we need more customization.

From block size to data structure, from transaction fees to transaction delays, from access mechanisms to security assumptions, from contract engines to token empowerment, the degree of customization of Rollup will be gradually upgraded in the future to provide more flexible solutions for applications. plan.

More interoperability

As mentioned earlier, the dominance of the Ethereum ecosystem in the blockchain ecosystem has a lot to do with the huge amount of liquidity locked in it. In the crypto market, since each chain exists independently, liquidity cannot exist in both chains at the same time. The increase in the number of rollups will lead to further division of liquidity, and liquidity has become a serious problem.

Stronger interoperability can reduce cross-chain friction and allow liquidity to travel more smoothly between different local chains. It can even be called shared liquidity. In line with the ideas advocated by Cosmos, projects such as OP Stack, Arbitrun Orbit, ZK Stack, and Starknet Stack are all trying to build a huge application chain ecosystem. Rollup built using the same technology stack has the same technical architecture, so it can obtain native Interoperability without the need to build cross-chain bridges.

More heavy staking

Currently, 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 pledged assets as a guarantee, resulting in low capital utilization and increasing startup costs for service providers.

Heavy staking would be a good solution, taking advantage of the huge pool of funds pledged by the Ethereum consensus to provide shared security for other services through heavy staking, while increasing income for pledgers and improving capital utilization. EigenLayer and Espresso are currently doing related work, and it is foreseeable that more services will use heavy staking to ensure economic security in the future.

To sum up, the actual biggest beneficiary of the development of RaaS is the application chain. Can the application chain concept proposed by Cosmos and Polkadot in the early years sprout new sprouts and achieve an explosion in the RaaS ecosystem? We will also wait and see.

Perhaps, only innovation at the application layer can drive the explosion of the RaaS ecosystem. After all, no matter how good a road is, it must have cars running on it to be considered a good infrastructure.