Polygon AggLayer: Uniting Modular and Monolithic Blockchain Architectures

Bitpush News
4 min readMay 12, 2024

The biggest debate between blockchains is whether to create a modular or monolithic architecture. Though both have pros and cons, the modular architecture’s primary downfall is the fractionalization of liquidity and activity on numerous chains that may not be able to communicate natively with one another. Polygon sees the aggregated blockchain as the next evolution of blockchain development and is creating the AggLayer to allow any chains, regardless of specific traits or design choices, to seamlessly and natively interact.

Originally, all blockchains followed a monolithic architecture, meaning there is a single, integrated environment for all decentralized applications and liquidity. While this approach offered interoperability within the chain, it faced scalability challenges and limitations regarding customization and sovereignty for ecosystem participants. For example, a DeFi application may have different priorities, like safety and security, over a fast-paced game. Solana and Aptos are two chains still following the monolithic model, and while it has proven valuable for creating a simple user experience with no bridging to L2s, Solana has recently been combating congestion issues from increased demand.

The next evolution of blockchains was modular architecture, which split blockchain components into separate layers like data availability, execution, and settlement. Ethereum spearheaded this initiative by pivoting to its rollup-centric roadmap and slowly transitioning into a settlement layer for rollups like Optimism, Base, and Arbitrum, where users interact with applications. Applications can also create specific rollups tailored to their unique needs, like choosing their virtual machine, data availability layer, and design to optimize speed, security, and cost uniquely.

However, modularity introduces fragmentation as liquidity and state disperse across different chains. The current solution requires complex and vulnerable bridging mechanisms or cryptoeconomic security that introduces latency in cross-chain transactions.

The AggLayer is what Polygon believes to be the next step in the evolution of blockchain design, combining the best modular and monolithic. It enables trust-minimized interoperability between sovereign chains, creating what they define as a “horizontally scalable multichain ecosystem that enables access to shared liquidity and state across connected chains.” Though this sounds complex, it effectively enables the scalability and customization of modular architectures while maintaining the unified liquidity and user experience of monolithic designs.

Today, a rollup “settles to Ethereum” by posting transaction data directly to the L1. Though this approach is simple, as it abstracts every L2 to simply being a smart contract with specific rules about withdrawal from Ethereum’s perspective, it requires each rollup to have its own bridge to Ethereum, and optimistic rollups require a 7-day waiting period for withdrawals. The AggLayer acts as a middle layer between rollups and Ethereum settlement, appearing to Ethereum as one contract but allowing rollups to interact with each other with low latency. Cross-chain transactions can occur without withdrawing to Ethereum and execute automatically, triggering transactions on multiple chains upon token arrival. The goal is to allow sub-section cross-chain atomic transactions, replicating the feeling of a Solana-like experience while allowing each chain full sovereignty.

Technically, the AggLayer works by having each chain establish its state on the AggLayer. The AggLayer’s role is to generate aggregated ZK proofs that settle to Ethereum, which trustlessly prove the validity of the chain’s recent transaction executions.

So far, the AggLayer does not have much adoption, with only Polygon’s zkEVM OKX’s upcoming X Layer rollup joining the initative. That being said, it’s feasible for any chain to join the AggLayer, including those in the Optimism Superchain, Arbitrum Orbit, alternative L1s, and even Cosmos app chains. Polygon has been criticized for spreading itself too thin among many projects, but it now seems to focus heavily on the aggregated layer.

The AggLayer is an impressive vision that supports blockchain sovereignty while also allowing for interoperability and cross-chain transactions. Though its success is far from guaranteed and primarily reliant on adoption from various chains, the Polygon team is well-equipped with the capital, network, and connections to make this a reality.

By Lincoln Murr

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