Towards scalable blockchains using service-oriented architectures

In recent years, blockchain applications beyond cryptocurrency has received tremendous attention due to its salient features which includes distributed management, security, anonymity, and immutability. However, conventional blockchains suffer from lack of scalability, high complexity, privacy, and governance. In this paper, we study the existing solutions introduced to address these limitations. We categorize these solutions into four groups which are: i) grouping nodes where the participating nodes are formed into smaller groups, ii) side channels where selected nodes form a child ledger attached to the main ledger to communicate privately, iii) optimized consensus algorithms that aim to reduce the overheads associated with committing new blocks, and iv) Blockchain-as-a-Service (BaaS) that employ service computing concepts and offload the blockchain management overheads to the cloud. A detailed discussion on BaaS is proposed along with a study of the existing cloud architectures. We elaborate on the advantages of employing blockchain to address challenges in service computing such as service recommendation. Finally, we discuss future research directions.