A Survey on Blockchain Interoperability: Past, Present, and Future Trends (2005.14282v3)

Abstract: Blockchain interoperability is emerging as one of the crucial features of blockchain technology, but the knowledge necessary for achieving it is fragmented. This fact makes it challenging for academics and the industry to seamlessly achieve interoperability among blockchains. Given the novelty and potential of this new domain, we conduct a literature review on blockchain interoperability, by collecting 262 papers, and 70 grey literature documents, constituting a corpus of 332 documents. From those 332 documents, we systematically analyzed and discussed 80 documents, including both peer-reviewed papers and grey literature. Our review classifies studies in three categories: Cryptocurrency-directed interoperability approaches, Blockchain Engines, and Blockchain Connectors. Each category is further divided into sub-categories based on defined criteria. We discuss not only studies within each category and subcategory but also across categories, providing a holistic overview of blockchain interoperability, paving the way for systematic research in this domain. Our findings show that blockchain interoperability has a much broader spectrum than cryptocurrencies. The present survey leverages an interesting approach: we systematically contacted the authors of grey literature papers and industry solutions to obtain an updated view of their work. Finally, this paper discusses supporting technologies, standards, use cases, open challenges, and provides several future research directions.

• The paper systematically reviews 284 academic and 120 grey literature documents, selecting 102 key sources to classify blockchain interoperability solutions.
• It categorizes methods into Public Connectors, Blockchain of Blockchains, and Hybrid Connectors, detailing techniques like sidechains, HTLCs, and blockchain-agnostic protocols.
• The study proposes a Blockchain Interoperability Framework aimed at establishing universal standards to enhance scalability and cross-chain collaboration.

A Survey on Blockchain Interoperability: Past, Present, and Future Trends

The paper "A Survey on Blockchain Interoperability: Past, Present, and Future Trends" by Rafael Belchior et al. addresses an intricate and pertinent topic within the expanding domain of blockchain technology: interoperability. The paper comprehensively analyzes how blockchain networks can communicate and collaborate effectively, a critical feature as blockchain technology continues to diversify into numerous platforms with distinct purposes and functionalities.

Overview and Classification of Blockchain Interoperability

The paper conducts a thorough literature review, examining 284 academic papers and 120 grey literature documents to piece together a comprehensive overview of the field. From this corpus, the authors meticulously selected and assessed 102 documents, which include both peer-reviewed papers and relevant grey literature, categorizing solutions into three primary categories: Public Connectors, Blockchain of Blockchains, and Hybrid Connectors.

1. Public Connectors: These solutions are primarily associated with the traditional cryptocurrency blockchains. Public connectors facilitate interactions between cryptocurrency systems, dealing chiefly with asset transfers across networks. This category includes mechanisms such as sidechains, notary schemes, and hash-time lock contracts (HTLCs). For instance, sidechains allow secure asset transfer between blockchains using two-way pegs, whereas HTLCs facilitate atomic swaps without relying on third-party intermediaries.
2. Blockchain of Blockchains (BoB): This framework integrates independent blockchains into a cohesive system that permits interaction and interoperability among them. BoB paradigms introduce the concept of customized blockchains tailored to specific applications, focusing on creating interoperable ecosystems rather than standalone silos. Systems like Polkadot and Cosmos represent this category by offering robust platforms for deploying interoperable blockchain networks and enabling cross-chain transactions.
3. Hybrid Connectors: Rooted in a more flexible and dynamic approach, hybrid connectors aim to bridge the gap between distinct blockchain infrastructures, facilitating seamless integration and communication across heterogeneous networks. Hybrid connectors encompass trusted relays and blockchain-agnostic protocols, aiming to offer a blockchain abstraction layer that promotes interoperability without necessitating substantial infrastructural modifications to the underlying blockchains.

Implications and Future Directions

The implications of blockchain interoperability extend into both theoretical frameworks and practical applications. From a theoretical standpoint, achieving seamless interoperability among blockchains enhances scalability while providing synergistic benefits through network effects. Practically, interoperable blockchains empower a multitude of use cases across various sectors such as supply chain management, finance, healthcare, and more, driving innovation and efficiency.

The paper posits that while blockchain interoperability has begun permeating the industry, it remains largely unexplored in terms of universally recognized standards. Proposed frameworks such as the Blockchain Interoperability Framework (BIF), introduced within the paper, offer foundational criteria to assess and advance interoperability solutions across varied blockchain environments.

An intriguing forward-looking aspect of the research involves the potential development of universally accepted interoperability standards, which could parallel the role of HTTP and TCP/IP in the web ecosystem. As the domain matures, the convergence of blockchain standardization efforts alongside technological advancements will likely foster rapid adoption and integration across more traditional sectors and emerging markets.

Conclusion

This survey by Belchior et al. serves as a vital resource for researchers and industry practitioners exploring the area of blockchain interoperability. Its systematic approach to classifying existing solutions and identifying gaps provides clarity and direction for future research endeavors. As interoperability solidifies its position as a crucial feature of blockchain technology, this research not only encourages further exploration but also sets the stage for transformative advancements in how decentralized networks interact and operate collaboratively on a global scale.