Interoperability Among Heterogeneous Blockchains: A Systematic Literature Review

Blockchain technology is evolving rapidly; it has proved to be capable of solving many of the issues encountered by industries such as banking, supply chain management, and healthcare. However, several challenges must be overcome for it to reach its full potential and be adopted on a large scale. In a blockchain context, interoperability is the ability to connect multiple networks, thus enabling the exchange of assets, the invocation of smart contracts, and the verification of data, all while ensuring consistency between systems. In reality, most of the existing blockchain networks operate in a stand-alone environment, isolated from other blockchain networks. This causes a lack of communication that further leads to restrictions imposed on data, i.e., preventing it from transmitting freely to and from various blockchains regardless of the underlying infrastructure. Given the potential of blockchain interoperability, researchers have proposed many protocols over the last few years, and the solutions being offered are on the rise. In this chapter, we will discuss the methodologies used in the available solutions and compare several of their characteristics, including throughput, average block confirmation time, and consensus mechanism. Furthermore, we will present the projects currently implementing these protocols and their future directions.