A Review of Blockchain Architecture and Consensus Protocols: Use Cases, Challenges, and Solutions

ver the last decade the blockchain technology has emerged to provide solutions to the complexity, performance and privacy challenges of using distributed databases. Over this time, the concept of blockchain has shifted greatly due to the rapidly evolving distributed applications in a collaborative ecosystem such as smart cities, social networking, governance, and smart healthcare, and the ultimate need for green computing, cost reduction for customers, and business growth for enterprises. Consequently, blockchain architecture has misaligned with the goals for a green collaborative digital ecosystem. Therefore, it becomes critical to address this vent and to build new frameworks to align blockchain with those goals. In this paper, we discuss the evolution of blockchain architecture and its consensus protocols, bringing a retrospective analysis and discussing the rationale of the evolution of the various architectures and protocols, as well as capturing the assumptions conducting to their development and contributions to building collaborative applications. We introduce a classification of those architectures and provide insights for future research directions in the field.