Synapse Chain

Synapse Chain is an Ethereum-based optimistic rollup designed to serve as a sovereign execution environment for cross-chain use cases. Synapse Chain will offer developers a generalized smart contract interface for building natively cross-chain use cases by leveraging Synapse’s cross-chain messaging system. Applications built on Synapse Chain will be able to execute their business logic across any blockchain.
The impetus to build a sovereign chain to facilitate cross-chain messaging comes from the core contributing team’s learnings working with teams building cross-chain applications, namely that a programming environment specifically suited for use cases built atop the messaging system makes managing deployment and state across chains much simpler, and that cross-chain business logic is much more efficient when hosted on a single execution environment. This allows for users to interact with state in an atomic way, even if it’s deployed across various blockchains. As a principle, complex business logic shouldn’t be spread amongst 10 blockchains.
Similarly, developers can birth a whole suite of new primitives with multi-chain state that’s deployed on a single blockchain. These primitives can then be used as building blocks for completely new user experiences and applications that are better tailored to our multi-chain reality.
Another novel feature of Synapse Chain is that it will be used to store the attestations made by Synapse’s security system on the validity of cross-chain transactions. In most other messaging systems, as the number of connected chains goes up, so does the number of contracts that have to be updated to keep track of every message. With Synapse Chain, only one chain needs to be updated with each valid cross-chain transaction, decreasing smart contract complexity, and ultimately, the gas costs required to use the system. Since Synapse Chain is a rollup that settles back to Ethereum, all historical attestations of the system’s cross-chain transactions are made available via Ethereum.
As mentioned above, Synapse Chain is built as an Optimistic Rollup. Why this route, as opposed to constructing a new monolithic chain? There are four primary reasons for this design choice:
  • EVM Compatibility
  • Security
  • User Experience
  • Simplicity
EVM Compatibility
Synapse Chain will leverage the EVM to ensure composability with the rich developer and application ecosystem built around it. Not only will building applications on Synapse Chain match the developer experience of existing EVM blockchains, but existing decentralized applications can easily be deployed to Synapse Chain with little to no architectural changes. This ensures that Synapse Chain can bootstrap a vibrant ecosystem of cross-chain applications from its earliest days.
While blockspace designed for more granular use cases can dramatically increase throughput, fees, and overall user experience, it often does so at the expense of security. Instead of needing to bootstrap independent security systems, optimistic rollups enable dapps to leverage the security and decentralization of Ethereum’s base layer, which has the highest security spend out of any generalized smart contract blockchain.
User Experience
Rollups offer throughput and scalability that is orders of magnitude higher than that of Ethereum. Transactions on Synapse Chain will be near instant and will cost a fraction of what they would on competing base layers, ensuring applications built on Synapse Chain can foster a user experience akin to that of centralized competitors.
Optimistic rollups provide a construction for an execution environment that is both simple and secure. By borrowing from Ethereum’s battle-tested infrastructure, Synapse Chain does not have to re-engineer new features from scratch. To that end, Geth will be Synapse Chain’s client software, meaning Synapse Chain is as close to Ethereum under the hood as possible. Adhering to Ethereum’s core design principles helps minimize new attack vectors that come with creating a new execution environment from scratch.

Synapse Chain Construction

Consistent with most rollup constructions, all Synapse Chain blocks will be stored within a smart contract on the Ethereum blockchain. Similarly, block production on Synapse Chain will be managed by a single sequencer, which is also responsible for state updates and submitting transactions back to Ethereum. Decentralization of Synapse Chain’s sequencer will follow the roadmap of prominent rollup protocols.
Upon launch of Synapse Chain, gas will be paid to the sequencer in ETH in order to foster the best user experience possible. Shortly after launch, the Synapse DAO could explore a number of mechanisms to tie use of Synapse Chain back to SYN in order to fortify the symbiotic relationship between Synapse Chain and the messaging system. While they are unique components, Synapse Chain can only succeed if the messaging system can provide trustless security, which SYN strives to incentivize.