Blockchain is a disruptive technology that has attracted the attention of the scientific community and companies, as proven by the exponential growth of publications on this topic in recent years. This growing interest is mainly due to the promise that the use of blockchain enables it to be verified, without including any trusted intermediaries, that the information received from the network is authentic and up-to-date. In this respect, blockchain is a distributed database that can be seen as a ledger that records all transactions that have ever been executed. In this context, smart contracts are pieces of software used to facilitate, verify, and enforce the negotiation of a transaction on a blockchain platform. These pieces of software are implemented by using programming languages, which are sometimes provided by the blockchain platforms themselves. This study aims to (1) identify and categorise the state-of-the-art related to smart contract languages, in terms of the existing languages and their main features, and (2) identify new research opportunities. The review has been conducted as a multivocal mapping study that follows the guidelines proposed by Garousi et al. for conducting multivocal literature reviews, as well as the guidelines proposed by Kitchenham and Charters for conducting mapping studies. As a result of the implementation of the review protocol, 4,119 papers were gathered, and 109 of them were selected for extraction. The contributions of this article are twofold: (1) 101 different smart contract languages have been identified and classified according to a variety of criteria; (2) a discussion on the findings and their implications for future research have been outlined. As a conclusion, it could be stated that a rigorous and replicable overview of the state-of-the-art of smart contract languages has been provided that can benefit not only researchers but also practitioners in the field, thanks to its multivocal nature.

Smart Contract Languages: A Multivocal Mapping Study

The emerging Smart Agriculture based on Internet of Things (IoT) is facing major challenges like data sharing, storage, and monitoring, primarily due to the distributed nature of IoT and massive scale We performed a review of the literature and found that blockchain performance, scalability, cost, and throughput are the major challenges in adopting blockchain for smart agriculture To overcome these challenges, this paper proposes a scalable and distributed data sharing system integrating access control for smart agriculture We demonstrate our approach in a smart agriculture setting, which consists of four tiers that are: smart agriculture, smart contract, Interplanetary File System (IPFS) and agriculture stakeholders (remote users) This paper explains in detail the different components of our proposed architecture Our approach uses anonymous identities to ensure users' privacy Our approach is fully scalable because a large number of resource owners can use their data sharing smart contracts to create, update or delete data sharing policies In addition, our approach does not require transaction fees when the smart contract receives a large number of policy evaluation requests For the sake of simplicity, we publish and test a single data sharing smart contract However, in practice, multiple smart contracts need to be deployed to allow each resource owner to securely share agriculture data with stakeholders Finally, we evaluate the performance of our proposed system on the EOS blockchain to show that the resource consumption (in terms of computing power and network bandwidth) introduced by our framework are insignificant compared to its scalability, cost and security benefits

Blockchain Smart Contract for Scalable Data Sharing in IoT: A Case Study of Smart Agriculture

BIM integrated smart contract for construction project progress payment administration

Blockchain presents a novel technology for improving existing paradigms in a wide span of domains, including project management. In this paper, we first review the state of the art blockchain use cases in project management to reveal the current status of blockchain research and to identify the blockchain application domains in project management. We then present a framework based on the review results, to guide implementers and researchers on blockchain design decisions about privacy, transparency, decentralization, blockchain type, and platform decisions, which are unique for a particular project management domain. The review results indicate that blockchain includes a variety of unique properties simultaneously, and presents multiple contributions for management of projects. However, technical blockchain design decisions are crucial for maximizing the benefits of the blockchain systems. The proposed novel framework enables a structured methodology for resolving crucial technical design decisions for maximizing the benefits of blockchain systems in project management and the review provides directions to the new blockchain research.

Blockchain in project management: a systematic review of use cases and a design decision framework

Being the most popular programming language for developing Ethereum smart contracts, Solidity allows using inline assembly to gain fine-grained control. Although many empirical studies on smart contracts have been conducted, to the best of our knowledge, none has examined inline assembly in smart contracts. To fill the gap, in this paper, we conduct the first large-scale empirical study of inline assembly on more than 7.6 million open-source Ethereum smart contracts from three aspects, namely, source code, bytecode, and transactions after designing new approaches to tackle several technical challenges. Through a thorough quantitative and qualitative analysis of the collected data, we obtain many new observations and insights. Moreover, by conducting a questionnaire survey on using inline assembly in smart contracts, we draw new insights from the valuable feedback. This work sheds light on the development of smart contracts as well as the evolution of Solidity and its compilers.

Large-Scale Empirical Study of Inline Assembly on 7.6 Million Ethereum Smart Contracts

One of the building blocks of our legal and economic systems in society is the indispensable reliance on contracts and trust systems to protect individual rights. Recently smart contracts are becoming prominent parts of various blockchain platforms. The goal of smart contracts is to eliminate the third party and centralized trust systems. Due to recent emergence of smart contracts, there is no well-defined framework that researchers can use to evaluate smart contracts under various blockchain platforms and differentiate between them. In this work, a survey on the prominent smart contract landscape specially those based on blockchain have been conducted. Based on the survey, an evaluation framework to assess smart contracts has been proposed. The framework is a set of criteria based on two major aspects; infrastructure related and development related criteria. The evaluation framework was peer-reviewed for reliability and validity. To measure the applicability of the proposed framework, it has been used to empirically evaluate some of the most prominent smart contract platforms. The results of the empirical evaluation have shown that the Ethereum blockchain smart contract exceeds the others in terms of development tools, resources, and community support. EOS blockchain smart contracts have the best execution speeds, and transaction costs. Lastly, Stellar blockchain has predictability and the best transaction builder to use in smart contract development concerning user friendliness. Recommendations for smart contract developers are provided in light of the research.

Imane Mokdad

Papers

Empirical Evaluation of Blockchain Smart Contracts