Cross-rollup composability: proof aggregation, shared sequencing and SUAVE
Quote408 words
Adds commentary to an interop overview: light-client ZK verification, validity proof aggregation layers, shared validity sequencing for atomicity, SUAVE as demand-side aggregator and shared sequencers needing stateful builders.
Key claims
Shared sequencers give same-block inclusion but not execution guarantees
Shared validity sequencing can add atomicity and conditional execution
SUAVE executors cannot guarantee inclusion on other chains
This great overview by @andyyy and @arjunnchand walks you through the different approaches to enable interop/composability in the modular era! 馃殌
Adding some thoughts as well! 馃挱馃憞
Would maybe add light-client based state verification through ZKPs to the list as well (e.g. @PolyhedraZK or @SuccinctLabs).
Validity proof aggregation layers will be big imo. Aside @sovereign_labs that follows this approach, this will also be the way @0xPolygon will take to enable interop among Polygon CDK based chains. Holy grail is a validity proof aggregation layer that can aggregate various different proof systems though (e.g. plonky2, Halo2, Boojum, etc.).
Also have some thoughts on the shared sequencing topic:
Shared sequencers indeed enable some degree of atomic composability as well through the promise of inclusion in the same block. As pointed out by @andyyy though, this does not equal execution guarantees.
However, solutions like Shared Validity Sequencing (as proposed by @UmbraResearch) can help here, which introduces an advanced block-building algorithm tailored for the shared sequencer to ensure atomicity and conditional execution guarantees. It also postulates the Implementation of shared fraud proofs among the participating rollups to enhance the integrity of cross-chain actions. While being geared primarily towards optimistic rollups, SSV can also be applied to validity rollups (that are naturally asynchronically composable) to enable synchronous composability.
A solution like SUAVE can help by providing economic atomicity (as any builder basically). However, only proposers (validators) have the power to guarantee transaction inclusion. SUAVE executors are not necessarily validators of other chains, and hence can鈥檛 guarantee atomic inclusion of cross-chain transactions. Shared sequencers on the other hand act as proposers of the rollups that opt into the sequencing solution. But since the shared sequencer doesn't execute transactions, it can鈥檛 guarantee that a transaction won鈥檛 revert upon execution. That鈥檚 why shared sequencers will need stateful builders such as SUAVE to sit in front of them. SUAVE basically anticipates that different cross-chain atomicity approaches will emerge & looks to support preference expression for all of them, which basically makes SUAVE a demand-side aggregator for cross-domain preferences.
Finally, I would add @axelarcore and @chainlink CCIP in the GMP section. Axelar is a highly versatile interop solution based on a Cosmos SDK PoS chain. Could be a key enabler of interop among L2s imo and also has an interchain token service (ITS) solution that addresses briding risk / liquidity fragmentation. Chainlink is similar to @LayerZero_Labs and using Decentralized Oracle Networks (DONs) instead of its own L1.
twitter.com/ayyyeandy/status/1712492669274873977
QUOTING @zerokn0wledge_
what do you think is the best solution to enable cross-rollup composability/interop? 馃
what do you think is the best solution to enable cross-rollup composability/interop? 馃