Decentralized ledger technology (DLT) is becoming ubiquitous in today’s society. However, organizations need to connect their existing systems and processes to blockchains (centralized, decentralized) securely and reliably, sometimes also implying that they need to connect blockchains (decentralized, decentralized). This challenge is known as blockchain interoperability.

We put the case forward that academia and industry must propose evaluation frameworks for blockchain interoperability solutions that address the three interoperability modes. Those are data transfers, asset transfers, and asset exchanges. In this position paper, we illustrate the remaining challenges of interoperability, focusing on the systematic evaluation of interoperability mechanisms based on the state of the art and our own experience. Our evaluation is a systematic online survey of 17 items targeting blockchain specialists. Our quantitative analysis shows that several interesting metrics can show promising directions for systematically evaluating integration solutions.