Conventional approaches to agreeing on transactions in monetary systems rely on trusted central authorities. Blockchain defies this model by achieving consensus through a community of peers in a decentralized network for validating transactions and maintaining an ordered record of transactions. The application domains for blockchain have expanded from cryptocurrencies to potentially any industrial system. However, there is still a lot of confusion regarding the advantage of using the blockchain instead of alternative technologies. The number of successfully deployed blockchain-based systems is still relatively small due to the lack of clarity regarding blockchain governance and the challenge of assessing the tradeoffs of blockchain-based solutions. As there are different types of blockchains, such as permissionless and permissioned, it often becomes hard to choose a suitable solution for a specific use case scenario. In this paper, we address these challenges by analyzing blockchain governance and related tradeoffs, including energy consumption, consensus, performance, and security. We contribute with a taxonomy guideline to provide insights on these tradeoffs and to facilitate effective identification of the suitable governance structure for blockchain-based solutions in various scenarios. The proposed taxonomy discusses different features of blockchain that includes energy consumption, consensus methods, performance, and security aspects to suggest the governance model (permissionless/permissioned/consortium) for a blockchain-based solution. Furthermore, this paper provides a tradeoff analysis of different consensus methods, such as PoW, PoS, PBFT, and PoA, considering important properties.

Open-cry electronic auctions have revolutionized the landscape of high-value transactions for buying and selling goods. Online platforms such as eBay and Tradera have popularized these auctions due to their global accessibility and convenience. However, these centralized auctioning platforms rely on trust in a central entity to manage and control the processing of bids, e.g., the submission time and validity. The use of blockchain technologies for constructing decentralized systems has gained popularity for their versatility and useful properties toward decentralization. However, blockchain-based open-cry auctions, are sensitive to the order of transactions and deadlines which, in the absence of a governing party, need to be provided in the system design. In this paper, we identify the key properties for the development of decentralized open-cry auctioning systems, including verifiability, transaction immutability, ordering, and time synchronization. Three prominent blockchain platforms, namely, Ethereum, Hyperledger Fabric, and R3 Corda were analyzed in terms of their capabilities to ensure these properties for gap identification. We propose a solution design that addresses these key properties and presents a proof-of-concept (PoC) implementation of such design. Our PoC uses Hyperledger Fabric and mitigates the identified gaps related to the time synchronization of this system by utilizing an external component. During the chaincode execution, the creation and submission of bids initiate requests to the time service API. This API service retrieves trusted timestamps from NTP services to obtain accurate bid times. We then analyzed the system design and implementation in the context of the identified key properties. Lastly, we conducted a performance evaluation of the time service and the PoC system implementation in time-sensitive scenarios and assessed its overall performance.

The Industrial Internet of Things (IIoT) promises automation, efficiency, and data-driven decision-making by real-time data collection and analysis. However, traditional IIoT architectures are cloud-centric and, therefore, struggle to handle large volumes of data, edge bandwidth constraints, and data confidentiality. Distributed edge-to-cloud computing emerges as a potential solution, also paving the ground for edge-to-cloud data analytics and distributed Artificial Intelligence (AI) to obtain insights for decision-making and predictive maintenance. Despite the potential, however, there is a lack of comprehensive studies identifying key requirements for distributed edge-to-cloud IIoT and analyzing to what extent emerging IoT platforms meet those requirements. The scope of this article is to survey existing literature to identify key requirements in IIoT from the perspective of distributed edge-to-cloud computing. We provide a comparative analysis of three prominent IoT platforms, namely ThingsBoard, Eclipse Ditto, and Microsoft Azure IoT, and assess how these platforms meet the key IIoT requirements. Finally, we identify open challenges and potential research opportunities based on the insights gained from the analysis of the three IoT platforms, thereby setting the stage for future work.

Blockchain technology is extensively used for cryptocurrencies and is considered for industrial applications due to features like decentralization, anonymity, and a tamper-proof history of transactions. However, the well-known blockchain trilemma of being unable to simultaneously meet the properties of decentralization, security, and scalability (DSS) negatively impacts widespread acceptance. Numerous solutions have been put forward in response to this challenge, aiming to increase performance and scalability while retaining the decentralized and trustless aspects. They range from introducing off-chain technologies to changing consensus algorithms and on-chain data structures. One of the most effective methods to accomplish horizontal scalability along with the growing network size could be sharding, which involves dividing the network of nodes into numerous shards or channels. The overhead of repetitive communication, storage, and processing at each node is decreased by this technique. This paper explores various sharding approaches to solve performance issues regarding blockchain. We review recent sharding technologies, including Polkadot, Ethereum Casper, and Cardano Hydra. We discuss the performance challenges of blockchains and provide essential insights into the tradeoffs.

Blockchain technology has been generating great interest by a variety of industry sectors. Realizing the strength of blockchain technology beyond its successful application in the cryptocurrency arena, researchers have been evaluating and using blockchain for applications such as supply chain management, the energy industry, health sectors, and much more. Some of the features include smart contracts, decentralization, consensus, immutable distributed ledgers, cryptographic hashing, and digital signatures. There are multiple types of blockchain and different consensus models. However, it is often a significant undertaking to determine if an application requires a blockchain. What kind of blockchain and consensus model is best suited for a given scenario? This paper addresses this challenge by evaluating different blockchain solutions along with the consensus models to determine the applicability for different use cases. We propose a guideline and applicability analysis framework (AAF) to determine whether an application needs a blockchain solution or not. The AAF is divided into 6 domains, 11 subdomains, and 45 controls. It is designed to ingest detailed user requirements to perform a weighted evaluation that is built on mathematical constructs to determine the scenario in which a blockchain-based solution is appropriate. Moreover, this article also includes an example of evaluating applicability through AAF with the help of a use-case scenario.

Blockchain is a secured, shared, and distributed ledger system that records and tracks resources without requiring a centrally trusted authority. In addition to cryptocurrency, blockchain can be used for supply chain, logistics, healthcare, energy industries, and other financial services.

However, blockchain technology faces several challenges, including energy consumption, security risks, governance, performance, and scalability. Hence, the government and private sectors are yet to consider blockchain-based solutions as a sustainable approach to building their business models. Addressing these challenges will enable blockchain technology to reach its full potential and become a transformative force in various industries. Scalability is a major challenge in blockchain, as reaching consensus when there is a large number of participating nodes requires significant computational power or complex repetitive communications among the nodes. This issue could be addressed with blockchain sharding.

This thesis investigates various opportunities, challenges, and tradeoffs related to blockchain technologies. Based on the governance model and quality attributes, we provide a tradeoff analysis considering technical properties, such as the performance and important architectural considerations about blockchain systems. Furthermore, we address the scalability issues regarding traditional blockchain solutions and identify the possibilities of sharding solutions to improve the performance and scalability of blockchain. Sharding is a technique to improve scalability by dividing the network into smaller parts called shards. Sharding allows blockchain networks to process more transactions per second (TPS) by distributing the workload across different nodes in the network. While sharding can improve the scalability of blockchain networks, it introduces some new challenges due to the consensus process and the requirements to maintain consistency between shards, which are part of our studies.

There are six major contributions. First, we conduct a literature survey of blockchain from the applications, challenges, and opportunities perspective. It presents some tradeoffs of blockchain, a comparison among different consensus mechanisms, and discusses challenges, including scalability, privacy, interoperability, energy consumption, and regulatory issues. Second, we evaluate the mobility gap for Electric Vehicle (EV) charging transactions by leveraging blockchain-based solutions. We also present a proof of concept using the Hyperledger consortium platform to evaluate the technical feasibility of the proposed approach. Third, we present a quantitative performance and scalability analysis of some popular private blockchain platforms, including Ethereum Quorum, Corda, and Hyperledger Fabric. Fourth, we propose a taxonomy guideline that provides critical insights for determining a suitable blockchain platform. Fifth, we propose a guideline and Applicability Analysis Framework (AAF) to determine whether an application needs a blockchain solution or not. This framework is designed to ingest detailed user requirements to perform a weighted evaluation built on mathematical constructs to determine the scenario in which a blockchain-based solution is appropriate. Finally, we present a review of recent sharding technologies, including Polkadot, Ethereum Casper, and Cardano Hydra to discuss the performance challenges of blockchains and provide important insights on the tradeoffs regarding blockchain trilemma: Decentralization, Security, and Scalability (DSS).

Traditional financial systems are based on trust in central authorities for secure transactions between parties. Blockchain on the other hand is a distributed ledger technology that stores data in a peer-to-peer decentralized network, where users can transfer money to each other without relying on centralized trusted intermediaries. Blockchain technology has received a lot of attention, mainly due to successful cryptocurrency applications (e.g., Bitcoin). Apart from cryptocurrency, blockchain can be used for supply chain, logistics, healthcare, energy industries, and other financial services.

Challenges with blockchain include the transaction processing time, resource-consuming network protocols (consensus algorithms), performance and scalability of the network, government regulations, etc. The government and private sectors are yet to consider blockchain-based solutions as a sustainable approach to building their business models. Inadequate insights about the tradeoffs and governance model for selecting the proper blockchain platforms have hindered the mass adoption of this technology.

The scope of this thesis is to investigate the opportunities, challenges, and tradeoffs of various blockchain technologies. We provide a tradeoff analysis considering technical properties such as the performance and scalability and important architectural/societal considerations about blockchain systems, based on the governance model and quality attributes.

There are four major contributions. First, we conduct a literature survey of blockchain from the perspective of applications, challenges, and opportunities. It presents some tradeoffs of blockchain, a comparison among different consensus mechanisms, and discusses challenges, including scalability, privacy, interoperability, energy consumption, and regulatory issues. Second, we evaluate the mobility gap for Electric vehicle (EV) charging transactions by leveraging blockchain-based solutions.  We also present a proof of concept using the Hyperledger consortium platform for the evaluation of the technical feasibility of the proposed approach. Third, we conducted a quantitative performance and scalability analysis of some popular private blockchain platforms, including Ethereum Quorum, Corda, and Hyperledger Fabric. Finally, we propose a taxonomy guideline that provides critical insights for determining a suitable blockchain platform.

Many countries in Europe are adopting a deregulated system where prosumers can subscribe with any energy supplier in an open market, independently of location. However, the mobility aspect of transactions in the existing system is not satisfactorily covered. For instance, if a person receives the service of charging an EV from a prosumer’s local outlet, he cannot pay to the prosumer directly without the presence of an intermediary system. This has led to a situation where the EV owners need to have a large number of subscriptions for EV charging providers and visitors cannot pay for the electricity used there. This study evaluates this mobility gap and proposes a solution for charging transactions using blockchain technology. Furthermore, we implement a proof of concept using the Hyperledger consortium platform for the technical feasibility of the proposed approach and evaluate the performance metrics such as transaction latency and throughput.

Blockchain is a technology for storing an immutable history of transactions in a decentralized platform by using cryptographic principles. Many industries have become interested in adopting blockchain within their IT systems. However, the accessibility, privacy, performance, and scalability aspects of different blockchain-based platforms are still legitimate concerns when designing an enterprise solution. Permissioned blockchain frameworks facilitate a way to immutably store confidential records. Numerous research studies have been carried out on the opportunities, challenges, application areas, and performance analysis of different public and permissioned blockchain-based platforms. However, the implication of blockchain in recent private enterprise solution requires detailed comparative analysis. This paper conducts a performance and scalability analysis of popular private blockchain platforms, including Ethereum (private deployment), Quorum, Corda, and Hyperledger Fabric. Each of these platforms is assessed by varying the workloads (no. of transactions and nodes) and determining the performance evaluation metrics such as throughput and network latency.

Blockchain is the underlying technology of a number of digital cryptocurrencies. Blockchain is a chain of blocks that store information with digital signatures in a decentralized and distributed network. The features of blockchain, including decentralization, immutability, transparency and auditability, make transactions more secure and tamper proof. Apart from cryptocurrency, blockchain technology can be used in financial and social services, risk management, healthcare facilities, and so on. A number of research studies focus on the opportunity that blockchain provides in various application domains. This paper presents a comparative study of the tradeoffs of blockchain and also explains the taxonomy and architecture of blockchain, provides a comparison among different consensus mechanisms and discusses challenges, including scalability, privacy, interoperability, energy consumption and regulatory issues. In addition, this paper also notes the future scope of blockchain technology.