Sequencing Architectures

Understanding sequencing architectures and how Syndicate's approach compares

Introduction

Sequencing is at the heart of how blockchain networks order and process transactions. This document compares different sequencing approaches based on how they impact key appchain benefits: cost efficiency, performance, programmable ordering, custom fee markets, atomic compatibility, and decentralization.

Sequencing Approaches Compared

Onchain Sequencing (Syndicate)

Syndicate's onchain sequencing moves transaction ordering logic from centralized services into transparent smart contracts deployed on an EVM-compatible rollup. This approach gives applications full control over their transaction ordering, economics, and governance while enabling unique capabilities like programmable transaction ordering, custom fee markets, and atomic composability between chains.

Users


Sequencing Chain (Contracts)
  │    • Rules
  │    • Permissions
  │    • Economics

Settlement Chain(s)
  • Execution
  • State changes
  • Security/finality
Key AdvantagesKey Disadvantages
  • Programmable transaction ordering
  • Economic sovereignty and control over fee markets
  • Atomic composability between chains
  • Progressive decentralization pathways
  • Transparent, verifiable rules onchain
  • Full control over governance
  • Requires onchain development expertise
  • Requires writing and maintaining sequencing contracts
  • Higher initial setup complexity

Centralized Sequencer

Centralized Sequencer provides centralized rollup hosting through cloud providers, offering the simplest deployment model for rollups but with significant centralization.

Users


Centralized Sequencer [Cloud Provider]
  │    • Single point of control
  │    • Managed infrastructure
  │    • Opaque configuration

Rollup Chain
Key AdvantagesKey Disadvantages
  • Easy setup and deployment
  • Highly configurable infrastructure
  • Simple mental model (centralized cloud)
  • Support for various rollup frameworks
  • Managed infrastructure
  • Completely centralized operation
  • Risk of liveness failures
  • Risk of data loss
  • Opaque configuration changes
  • Keys managed by provider (requires significant trust)

How Syndicate's onchain sequencing relates: Onchain sequencing pairs well with centralised rollup hosting by replacing the centralized sequencer component. This reduces the risk of liveness failures and data loss by storing critical information onchain instead of in centralized cloud services. Centralised hosting can still provide value through RPCs, developer tooling, bridge UIs, etc.

Shared Sequencing

Shared sequencing combines individual sequencers from multiple rollups to jointly order transactions between them, enabling cross-chain composability and potentially creating revenue through mechanisms like shared block auctions.

               ┌─────────────────┐
               │ Shared Sequencer│
               └────────┬────────┘

           ┌────────────┼────────────┐
           ▼            ▼            ▼
        Chain 1      Chain 2      Chain 3

• Common sequencer for multiple chains
• Standardized transaction ordering
• Coordinated block production
Key AdvantagesKey Disadvantages
  • Standardized approach across networks
  • Enables atomic composability
  • Creates cross-chain revenue opportunities
  • Positive network effects
  • Shared block auctions potential
  • Top-down market adoption required
  • Difficult to modify auction mechanisms
  • Rollups resist giving up sequencer control
  • Winner-take-all dynamics

How Syndicate's onchain sequencing relates: Onchain sequencing enables atomic composability by design, allowing networks to build "bottom-up" shared sequencing by optionally synchronizing their rulesets. This approach lets chains gradually adopt interoperability on their own terms, rather than requiring top-down mandates where everyone joins the same system.

Based Sequencing

Based sequencing allows transaction ordering to inherit Layer 1 security and liveness by using L1 validators to order and publish transactions, theoretically providing stronger decentralization.

L1 Validators

     │ • Inherits L1 security
     │ • High gas costs

L2 Chain ◄─── Gateway Services
Key AdvantagesKey Disadvantages
  • More onchain than traditional rollups
  • Strong liveness guarantees
  • Inherits L1 security
  • Solid theoretical decentralization
  • High gas costs from Ethereum usage
  • Relies on gateway services
  • Less decentralized in practice
  • Preconfirmation systems reintroduce centralization

How Syndicate's onchain sequencing relates: Syndicate's approach applies based sequencing principles at the L2 level (hence "metabased sequencing"), aligning with Vitalik's original vision of smart contracts that anyone can write to. This provides many of the benefits of based sequencing while avoiding the high L1 gas costs.

Syndicate can also potentially leverage based sequencing for a sequencing chain L2, which could improve liveness at the cost of higher fees—a tradeoff that might be worthwhile for certain appchains.

DA Layers

Data Availability (DA) layers like Celestia and EigenDA provide specialized solutions for storing blockchain data cheaply and efficiently, but with limited programmability and temporary storage.

        DA Network
     ┌──────┴──────┐
     │             │
  Chain 1        Chain 2

• Temporary storage
• Limited programmability
• Cost-effective data availability
Key AdvantagesKey Disadvantages
  • Low cost data availability
  • High transaction throughput
  • Wide ecosystem acceptance
  • Used by many rollup frameworks
  • Limited or no programmability
  • Data typically expires after a period
  • Often requires centralized data posting
  • No transaction ordering logic

How Syndicate's onchain sequencing relates: Syndicate's sequencing chain provides data availability while adding programmability and permanent storage. DA layers still have their place—Syndicate uses EigenDA in its sequencing chain—but onchain sequencing offers additional capabilities that pure DA layers cannot provide.

Vertical L1s/L2s

Alternative L1/L2 implementations like MegaETH and Monad focus on vertical scaling through techniques like parallelization or specialized hardware to improve performance.

High Performance Chain

    ┌────┴────┐
    ▼         ▼
Shard 1    Shard 2
• Parallel processing
• Vertical scaling
• Limited economic control
Key AdvantagesKey Disadvantages
  • Streamlined deployment process
  • Potentially better performance
  • Strong network effects potential
  • Specialized hardware optimization
  • High end-to-end latency
  • Applications can't control economics
  • Less battle-tested than established rollup infrastructure

How Syndicate's onchain sequencing relates: Syndicate bets on horizontal scaling through multiple application-specific chains rather than vertical scaling through a few high-performance chains. This approach gives applications control over their economics and governance, which is particularly appealing to developers who want to capture value within their own ecosystems rather than surrendering it to the underlying chain.

Avalanche Subnets and Cosmos Chains

These approaches allow developers to create new chains on top of their respective frameworks, with Avalanche focusing on EVM-compatible subnets and Cosmos enabling a wider range of chain architectures.

     Main Chain (Avalanche/Cosmos)

     ┌──────┴──────┐
     ▼             ▼
Independent     Independent
   Chain          Chain
     │             │
  • Custom      • Custom
  • Consensus   • Consensus
  • Validators  • Validators
Key AdvantagesKey Disadvantages
  • Complete flexibility in chain design
  • Fewer dependencies (independent chains)
  • Highest sovereignty for applications
  • Custom consensus mechanisms possible
  • Requires bootstrapping consensus
  • Complex bridging between chains
  • Complex cross-chain messaging setup
  • Significant operational overhead

How Syndicate's onchain sequencing relates: Onchain sequencing enables launching application-specific chains without the need to bootstrap consensus, significantly reducing the barrier to entry for new, smaller, or pre-token networks. While Cosmos chains offer maximum sovereignty, they require substantially more work to launch and maintain.

Key Tradeoffs

Each sequencing approach offers distinct tradeoffs:

  • Centralized Sequencer: Simple but centralized
  • Shared Sequencing: Coordinated but requires top-down adoption
  • Onchain Sequencing: Programmable and sovereign but more complex
  • Based Sequencing: Secure but expensive
  • DA Layers: Cost-effective but temporary
  • Vertical L1s/L2s: High performance but limited control
  • Avalanche Subnets and Cosmos Chains: Maximum sovereignty but high operational complexity

Syndicate's onchain sequencing combines the programmability of smart contracts with L2 efficiency, enabling applications to maintain economic sovereignty while achieving scalability through horizontal growth.

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