Taxonomy

Domains are best understood along a spectrum of possible rollup architectures compared to other ecosystems.

Enshrined Rollups

Domains are effectively enshrined rollups. An enshrined rollup is a particular type of rollup that is directly supported and integrated into the base protocol of the underlying blockchain, ensuring that the rollup's features and functionality are maintained and enforced by the network's consensus rules. This built-in support enhances the rollup's security, interoperability, and adoption while providing the benefits of a typical rollup, such as increased throughput and reduced transaction fees.

Standard Rollups

While regular rollups on Ethereum are validated through smart contracts, domains are validated by the Subspace core protocol, making them more similar to parachains on Polkadot. Unlike parachains with a monolithic validation model and a permissioned deployment system, domains support a modular validation framework and permissionless deployment process. Unlike Cosmos zones and Avalanche subnets, domains have shared security and trust-minimized interoperability since they all settle on the root chain.

Sovereign Rollups

Like sovereign rollups on Celestia, domains leverage the base layer protocol for consensus and data availability but extend this model to include a shared settlement layer as the default pattern. This is made possible by allowing operators to re-stake, as initially proposed by Free2Shard and later implemented within the EigenLayer protocol on Ethereum. Unlike Eigenlayer, which is implemented through smart contracts, Subspace enshrines the re-staking model within the semantics of the core protocol.

Permissionlessness

There are several key stages of bringing a domain to existence and operating on it described in the Workflow and each of this stages assumes a different level of permissionlessness:

• Staking, operating on most domains and nomination are completely permissionless as long as the prospective operator has enough funds for the minimum stake at their disposal. Operators are also free to unstake and exit at any time or choose to stake on another domain. Some domains may choose to restrict who can operate on them via an allow list, but this is not the defaul.

• Instantiation (copy) of an existing domain is permissioned on the current Gemini-3h network, but the plan is to make this process permissionless in the future.

• Open a channel between domains for cross-domain messaging has to be allowed by owners of both domains, but doesn’t require consensus governance approval.

• Open a channel consensus to domain can currently only transfer funds and has to be allowed by consensus governance.

• Register a new runtime to create non-EVM or Substrate domains is permissioned and requires consensus governance approval.