SoK: Systematizing Blockchain Interoperability through Layered Architecture and Layer 2 Interoperability

Blockchain networks were not originally designed with interoperability and standardization as core requirements, leading to significant fragmentation within the ecosystem. Achieving seamless cross-chain interaction is essential to overcoming these limitations. This paper surveys existing solutions and introduces a layered framework for advancing blockchain interoperability research and development. It proposes a unified transaction flow model, which abstracts transaction processes into six distinct stages while accounting for platform-specific nuances. Additionally, it explores Layer 2 interoperability as a critical new direction for addressing scalability and performance challenges. The paper also discusses developer tools and frameworks that facilitate interoperable blockchain applications, simplifying the development process. Finally, it examines interoperability use cases and applications, emphasizing practical benefits and real-world implementations.