Abstract
Blockchain technology has the potential to revolutionize industries by
offering decentralized, transparent, data provenance, auditable,
reliable, and trustworthy features. However, cross-chain
interoperability is one of the crucial challenges preventing widespread
adoption of blockchain applications. Cross-chain interoperability
represents the ability for one blockchain network to interact and share
data with another blockchain network. Contemporary cross-chain
interoperability solutions are centralized and require re-engineering of
the core blockchain stack to enable inter-communication and data sharing
among heterogeneous blockchain networks. In this paper, we propose an
application-based cross-chain interoperability solution named appXchain
which allows blockchain networks of any architecture type and industrial
focus to inter-communicate, share data, and make requests. Our solution
utilizes the decentralized applications as a distributed translation
layer that is capable of communicating and understanding multiple
blockchain networks, thereby delegating requests and parameters among
them. The architecture uses incentivized verifier nodes that maintain
the integrity of shared data facilitating them to be readable by the
entities of their network. We define and describe the roles and
requirements of major entities of inter-operating blockchain networks in
the context of healthcare. We present a detailed explanation of the
sequence of interactions needed to share an Electronic Medical Record
(EMR) document from one blockchain network to another along with the
required algorithms. We implement the appXchain solution with
Ethereum-based smart contracts for two hospitals and also present its
cost and security analysis. We have made our smart contracts code and
testing scripts publicly available.