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Weekly Rollup #6

For the week ending March 17th

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📣 News & Announcements

The Espresso Sequencer

This past week, Espresso Systems published a detailed overview of the Espresso Sequencer, a product that was first unveiled by the team late last year (2022).

The complete paper can be broken down into five parts. 

  1. Introduction

  2. Espresso Sequencer Motivations

  3. Espresso Sequencer Design Principles 

  4. Building the Sequencer (component overview)

  5. Summary & Roadmap

What is Espresso Systems  

Espresso systems is a web3 company focused on zero-knowledge technology in order to provide developers with scalability and privacy-enhancing features.

As a reminder, “zero knowledge (zk) proofs” can be used as both a scaling mechanism, as well as a privacy-enhancing mechanism for blockchains. Most of the big names in the space today are using zk-proofs to provide Ethereum with improved scalability (StarkWare, Polygon, etc.), while other names are employing the use of zk-proofs for privacy, such as Z-Cash. 

Espresso is building different zk-products to help with both. Their most popular solution is “Configurable Asset Privacy on Ethereum” (CAPE). The idea here is that privacy should be configured and set by each individual team. As we know, blockchains today (Ethereum, Bitcoin, etc.) are not private at all, which has led to the development of entirely private networks such as Monero. CAPE is targeting the group in the middle. and allowing each team to set its own privacy configurations or standards.

Other tools they’re offering include a zero-knowledge proof system (Hyperplonk), and the Espresso Sequencer (HotShot), “a system that decentralizes transaction sequencing for layer 2 scaling solutions on Ethereum without compromising on their scale or speed.”

What is a Sequencer 

In short, a sequencer is in charge of ordering transactions. 

To explain further, a rollup consists of several components: a client software, a mempool, a virtual machine (VM), a prover, a sequencer, and a rollup contract on the L1. When users submit rollup transactions, they get sent to the “mempool”. From here, sequencers gather the transactions and order them in the way they should be processed by the VM. You can imagine the sort of power a user has when controlling the way our transactions are executed, which is why decentralizing the sequencer is one of the biggest milestones for any existing Ethereum rollup.

As of today, pretty much all rollups operate under a centralized sequencer, whereby only a select few are chosen to provide the service of ordering transactions, creating concerns like transaction censorship, and MEV frontrunning. 

Espresso aims to build a decentralized sequencer network that will allow any existing rollup to plug into in order to receive this transaction ordering service (a universal sequencer network). The same group of sequencers will be ordering transactions across several different  L2s, rather than each rollup having its own unique sequencer set. 

The Espresso Sequencer

The Espresso Sequencer is a decentralized sequencing network for rollups that is designed to provide secure, high throughput, low latency transaction ordering, and availability. “This utility will not only allow rollups to decentralize but will also introduce to rollups the interoperability advantages of a shared sequencing layer”.

More specifically, the Espresso Sequencer is a consensus network.

The way this works is that the HotShot validators, which is expected to be the same group of validators from the Ethereum network via Eigen Layer, come to a consensus on how our rollup transactions are ordered. If we trust HotShot consensus, then we can assume that transactions are “finalized” as soon as they pass through the sequencer network. That being said, this only takes care of the “rollup consensus”, meaning the transactions still have to be “finalized” in the eyes of the L1 (Ethereum) consensus protocol. You can also think about the different types of finality as soft vs. firm finality.

What’s Next?

In November of last year, Espresso released “Americano” the first internal testnet of this sequencer network. 

According to the recently published paper, the “Doppio” testnet is up next for deployment and will mark the first steps to supporting live rollups. Rollup teams that are interested in integrating the Espresso sequencer can start reaching out to the team. 

For anyone interested in learning more about the Espresso Sequencer, you can check out the official paper, or docs.

Avail spins off from Polygon Labs

On March 16th, the Avail team announced that it will now officially be operating as its own unique network, independent of Polygon. 

As part of its separation from the Polygon Labs & Foundation teams, Avail will create a new not-for-profit foundation, and will eventually grow to a decentralized model governed by its community. Avail will remain led by Anurag Arjun, who first started developing Avail back in 2020. To help ensure Avail remains credibly neutral, Anurag, Polygon Labs co-founder, has stepped down from his role at Polygon for good. 

For anyone unaware, Avail is a modular blockchain that specializes in data availability, and has been under development by the Polygon team since 2020.

If we recall, blockchains typically have four duties: execution, security, consensus, and data availability (DA). These four duties make up the three blockchain layers: execution layer, settlement layer, and DA/consensus layer. A monolithic blockchain consists of all three layers within its single chain, whereas a modular blockchain splits the layers up and specializes in one particular area. 

Avail decouples the data availability layer from execution and settlement, strictly focusing on the DA & consensus portion. Other teams can deploy their own rollups (execution environments) on top of Avail, and because Avail only worries about DA & consensus, it for the most part does not care what virtual machine you use (hence, Polygon SVM), opening the door for extreme flexibility and innovations.

Some of the use cases they listed in the article include:

  • Sovereign Chains/Rollups: Sovereign rollups are different than a typical rollup we’re used to today in the fact that they’re not tied to an underlying settlement chain (Arbitrum settles on Ethereum for example). Rather than having a “settlement” chain be in charge of checking and validating proofs, the task is left to the sovereign chain itself. With projects like “Sovereign”, developers will be able to launch their own “sovereign” zk-rollup on top of Avail. 

  • Validiums: There is one key difference between rollups and validiums, mainly the fact that rollups publish their data directly on the L1 settlement chain, whereas validiums are like rollups that publish their data to a different network. This would be like Arbitrum posting its transaction data to Avail rather than to Ethereum. 

  • Optimistic chains, & more

Aside from all this, Anurag has mentioned in the past that each Polygon zk-rollup solution may have its own sovereign rollup on top of Avail in the future. Not only this, but he also mentioned some sort of settlement layer being added to Avail as well.

Polygon SVM is one of the earliest examples of a rollup utilizing Avail for data availability and consensus. Polygon SVM is a customized rollup powered by Solana’s virtual machine (Sealevel), and using Avail for DA & consensus. This means Solana’s high throughput VM, combined with the EVM ecosystem thanks to Avail. You can check out our past newsletter to learn more about Polygon SVM.

Avail represents a new “lego” being added to the modular stack, and we’re excited to see what developers build with this new block. 

As of today, Avail is up on testnet, and is expected to go live on mainnet later this year. You can follow the Avail team on Twitter to stay up to date with the project.

Introducing Worlds EVM

On March 16th, it was announced that the Worlds team will be using Eclipse to build its own EVM rollup, entirely dedicated to its web3 game.

What is Worlds

The same team that developed Unreal Engine 5 is now developing Worlds. Worlds is focused on building different tools and infrastructure that will “allow studios to deliver rock-solid multiplayer experiences without a AAA budget.” 

Aside from developing different infrastructure tools for developers to leverage, Worlds will also be releasing its own set of games. As of today, they have only announced one game, Waifu Tactical Force, which is a web3 free-to-play multiplayer shooter (think of Call of Duty in terms of concept). In fact, this title was just introduced during ETHDenver just a couple of days ago. 

For anyone familiar with shooter-based games, you’ll know that they require very high throughput - it’s not fun to play this type of game if your weapon takes as much as two seconds to fire.

This is the reason Worlds will be building on its own dedicated EVM rollup.

What is Eclipse

Eclipse is a “rollup as as service” (RaaS) provider, enabling teams to choose between different blockchain features and components in order to build their own custom, dedicated execution environment.

These execution environments (rollups) are then connected on top of Eclipse’s settlement layer, which itself is a rollup built using the Sealevel VM (used within the Solana ecosystem). This means that not only will the rollups benefit from having their own dedicated environment (no sharing computational resources with other dapps), but all rollups will also get to benefit from Sealevel’s “parallelism”, which is the core feature behind the VMs high throughput capabilities.

Worlds EVM Component Breakdown

In the image above, we can see how Worlds EVM is broken down (along with Polygon SVM, which was Eclipse’s first partnership announcement). 

Worlds is its own EVM chain that uses Celestia for DA, making this the first gaming-specific rollup to deploy using Celestia. Because Worlds will be using the EVM, they’ll remain connected to the Ethereum community and ecosystem, while still benefiting from the “parallelism” aspect mentioned earlier. 

World's goal is to support thousands of users and having extremely low latency, while also having near-free transaction costs. They hope to accomplish this with Eclipse.  

You can follow the Worlds team on Twitter if you want to stay up to date with their game’s upcoming testnet launch.

AltLayer 100 Flash Layer campaign ends

March 10th marked the conclusion of AltLayer’s “100 Flash layers” campaign, a 7-day event where 100 developers got the opportunity to build and deploy their own rollup in just a couple of minutes and a few clicks. 

There were several NFT & gaming-related projects that deployed over the 7-day period, such as “Mother Staker”, “SoulFans, DePets, and more. In fact, you can check out the official “project showcase” page here. 

Altogether, the campaign saw over 105M+ transactions across all Flash Layers, “at an average of 173 TPS.” This is an even crazier stat when you realize that these projects are using Ethereum for settlement and security. For a more detailed breakdown of the Flash Layer stats, you can check out this page

All in all, the “100 Flash Layers” campaign proved to be a successful event in showcasing the power of disposable rollups. 

What is AltLayer

AltLayer is a no-code rollup as a service provider, where teams “pay as they go”. Similar to Eclipse, AltLayer enables developers to build, and launch their own custom, dedicated rollups. What makes AltLayer unique, however, is that they provide “disposable” rollups, which in other words means rollups with an expiration date. 

You can learn more about Altlayer here if you’re interested.

More News & Announcements

📚 Discourse & Education

How do rollups ACTUALLY work?

In his talk “How rollups actually work”, Kelvin from Optimism offers an excellent mental model for rollups. Here’s his framing:

  • A rollup is simply a function over an input array

  • Two important properties of the input array are ordering and data availability

  • Ordering is important because if the order of the input array changes, the output array also changes

  • Data availability is important because if you don’t know what the inputs are, you can’t compute over them

  • Therefore, rollups are defined by the data and the ordering of that data - you are deriving the rollup from the parent system

To more explicitly map this mental model to familiar modular terms, the input array is the L1 blockchain, the output array is the rollup blockchain and the properties mentioned demonstrate that the L1 blockchain is the consensus and DA layer.

But what about settlement?

Kelvin outlines settlement functionality like validating contracts / proofs / etc., but intentionally separates them as bridging functionality. He buckets proofs under “ways to make bridges work”, listing the following options:

  • One trusted authority

  • Multiple trusted authorities

  • Light clients

  • Fault proofs

  • Validity proofs

He covers more ground in his (very entertaining) presentation, so we’d recommend watching it.

Is that it? Has consensus been reached? Does that settle how to think about rollups? 

Not quite. Like many of us, you probably thought rollups worked this way 👇 so you likely still have unanswered questions.

Namely - questions around settlement. Why was it demoted?? Look at that scary monster block thing with the guns! Looks secure to me!

In his talk “How rollups actually actually work”, Toghrul from Scroll offers a very different framing that shines a light onto settlement mechanics and how “classic” rollups work (typical Ethereum rollups AKA smart contract rollups AKA settled rollups). He places greater emphasis on settlement by segmenting different rollup types, defining them by how they handle fork choice rules.

As a refresher, fork choice rules come into play when there are multiple versions of history (ordered transactions) that need to be picked between. In the below example, all three forks contain valid transactions. L1 figures this out via consensus mechanism, but rollups don’t do that kind of consensus. So which fork does the rollup treat as the source of truth?

Here’s where Toghrul draws a distinction between classic and sovereign rollups:

  • In classic rollups, the base layer defines the fork choice rule

  • In sovereign rollups, the protocol participants define the fork choice rule

Ok, zooming back out. We’ve used a simple mental model to illustrate the essence of rollups and walked through the mechanics that distinguish rollup types. But these POVs ~feel~ very different - do they conflict?

As it turns out, not really! Kelvin and Toghrul actually agree on how rollups “work”. This is evident by how they both describe the rollup’s relationship with its ordering and DA layer.

The debates around settlement and canonical chains are not actually technical debates, they are social debates. It all comes down to “the social contract between the rollup community” and how that community wants to set rules for parsing L1 data. The distinction between classic and sovereign rollups is worth making, but we should place less focus on semantics and more focus on the resulting tradeoffs:

Basically everything else about rollups

Now that you have a foundation for how to think about rollups, it’s time we let you know that there is actually no such thing as rollups. That’s right, rollups aren’t real!

However, if they were, Jon Charb would have you covered this week.

Jokes aside - Jon wrote an incredible, comprehensive article on the rollup landscape. It’s a long but mandatory read.

More Discourse & Education

That's all for this week! Thanks for reading 🧱🎬

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