Is It Time to Rename Parachains to Rollups in Polkadot’s Ecosystem?

In mid-October 2024, Filippo Franchini sparked a discussion on the Polkadot Forum about renaming "parachains" to "Polkadot rollups." The suggestion aimed to improve SEO visibility and align Polkadot terminology with industry standards, especially as Polkadot is evolving with the upcoming JAM (Join-Accumulate Machine) update. Franchini emphasized the need for this change to future-proof Polkadot’s ecosystem, as "rollup" is more widely recognized and neutral, unlike the more Polkadot-specific term "parachain." This debate gained traction with varying perspectives from the community, some supportive of the potential rebranding to enhance discoverability and industry alignment, while others were cautious about abandoning an already well-known term.

Feedback ranged from concerns about brand recognition to technical considerations on how "parachains" function and the JAM update's potential impact on their role. Some commenters highlighted that JAM's new core model might render "parachain" obsolete, suggesting the more generic term "rollup" would better reflect its flexibility and broader usage across blockchain networks.

To properly assess the potential name change from "parachains" to "rollups," it is essential to first understand the different types of rollups and their technical workings. Rollups, broadly categorized as optimistic rollups and zk-rollups, have become central to scaling solutions in the blockchain space. A comparative analysis of how these rollups function versus Polkadot's current parachains can help clarify whether the shift in terminology aligns with Polkadot’s vision under the upcoming JAM upgrade. This comparison will also highlight the operational benefits or drawbacks of adopting such a term.

JAM and the Evolution of Parachains in Polkadot’s Ecosystem

JAM (Join Accumulate Machine) represents a significant evolution in Polkadot’s infrastructure, marking a departure from the traditional Relay Chain model. With JAM, Polkadot will shift to a more modular, flexible framework where the Relay Chain is replaced with a permissionless system. Parachains, which currently function as the backbone of the ecosystem, will no longer be the only way to interact with the network. Instead, JAM introduces the concept of "services" that can operate independently on the network without requiring parachain slots through costly auctions. This opens up a more accessible ecosystem where developers can deploy smart contracts and services more freely.

For parachains, this change means they will no longer hold a singular privileged position. While they remain "first-class citizens," JAM allows other services to function in parallel, diminishing the exclusivity of parachain slots. This shift invites reconsideration of how parachains are positioned within the ecosystem, leading to discussions, such as the one raised by Filippo Franchini, about whether renaming them to "rollups" might better reflect their evolving role in Polkadot under JAM's new architecture.

This sets the stage for a comparison of various rollup types to evaluate whether the term "rollup" aligns with the future direction of parachains.

Rollups and Their Types:

Rollups are Layer 2 scaling solutions designed to process transactions off the main chain (Layer 1), reducing the workload and improving scalability. The key idea behind rollups is that they bundle or "roll up" many transactions and then submit proof of these transactions back to the main chain. There are two primary types of rollups:

1. Optimistic Rollups:

   • Optimistic rollups assume transactions are valid by default. The term "optimistic" stems from the assumption that no malicious behavior has occurred. They do not require immediate verification of each transaction, which helps improve efficiency and throughput. However, they include a fraud-proof mechanism, where validators can challenge a transaction within a set period. If the challenge is valid, the transaction is reverted.

   • Example: Arbitrum and Optimism on Ethereum.

2. ZK-Rollups (Zero-Knowledge Rollups):

   • ZK-rollups generate cryptographic proofs (specifically, zero-knowledge proofs) for each transaction or batch of transactions. These proofs are submitted to the main chain, guaranteeing that all transactions are valid without needing individual transaction verification on-chain. This approach is generally faster and more secure but computationally intensive.

   • Example: StarkNet and zkSync.

Parachains and Their Evolution in JAM:

Before the JAM update, parachains in Polkadot function as sovereign blockchains that connect to Polkadot's Relay Chain. They operate independently, handling their own execution and state transition functions, but rely on the Relay Chain for shared security and interoperability. Parachains require developers to bid for a limited number of parachain slots through auctions, a costly and time-consuming process.

With the JAM upgrade, parachains will evolve, reducing these constraints and moving closer to a permissionless, rollup-like structure. JAM introduces services built directly on the Relay Chain, allowing developers to bypass the auction system and build freely, similar to how rollups operate permissionlessly on Layer 2 of Ethereum. JAM also introduces Coretime, where computational resources are purchased and traded flexibly, enhancing the economic scalability of Polkadot’s infrastructure.

Comparison: Parachains vs Rollups

• Security: Both parachains and rollups rely on the security of the base layer. For parachains, it’s Polkadot’s shared security model, while rollups inherit security from Ethereum (or any Layer 1 they’re built on).

• Transaction Processing: Rollups (especially ZK-rollups) focus on off-chain processing and then submit proofs to the main chain. Parachains, however, are more independent—they handle their own full state execution.

• Scalability: With the JAM update, parachains will become more modular and scalable, functioning more like rollups by allowing permissionless services on Polkadot. This brings parachains closer to rollups in terms of flexibility and cost-efficiency.

• Deployment: Rollups offer easy deployment without needing a significant upfront investment, which is the current case for parachains. JAM will address this by allowing services to be deployed without auctions.

• Use Case Flexibility: Post-JAM, Polkadot’s parachains will offer both traditional parachain functionality and rollup-like services, allowing developers to choose between sovereign chain setups or more modular service deployments.

In summary, Parachains after JAM will resemble rollups in flexibility, permissionless nature, and scalability, but they will still differ as sovereign chains capable of managing their full execution, unlike the more execution-dependent rollups.

Positive and Negative Points of Renaming Parachains to Rollups

In the Polkadot forum, a lively discussion arose around renaming "parachains" to "rollups," with both supporters and critics expressing their views.

Positive Points:

• SEO and Visibility: Filippo Franchini suggested that renaming parachains would improve Polkadot’s SEO and visibility within the broader blockchain ecosystem.

• Industry Alignment: Adopting the term "rollups" aligns Polkadot more with existing industry terminology, making it easier for outsiders to understand its functionality.

• Future-Proofing: With JAM’s evolution, using "rollups" could reflect the flexibility and permissionless nature of services built on the Relay Chain.

Negative Points:

• Brand Awareness: Some users noted that the term "parachain" is well-known and differentiates Polkadot from its competition. A rebrand could require significant effort to rebuild brand identity.

• Potential Confusion: Critics raised concerns that using the term "rollup" may confuse people, especially regarding how Polkadot differs from Ethereum’s zk-rollups and optimistic rollups.

• Technical Distinctions: Parachains function as independent chains, while rollups primarily handle off-chain processing. Merging the terms might blur these important distinctions.

Suggested Names and Solutions:

• Several alternative names were proposed, including "cynical rollups," "parachain rollups," and "secure rollups."

• A potential approach involves keeping both terms, with a glossary that explains parachains versus rollups for clearer communication across documentation.

In conclusion, while renaming parachains to rollups could improve Polkadot’s industry visibility and align with broader terminology, the community should carefully weigh the costs, especially around branding and potential confusion. The JAM update provides a natural point to consider such changes, but further discussion is necessary to determine the best path forward.