Abstract
This chapter describes blockchains and illustrates this explanation using the results of a prototype project for an industrial application for a construction project. The chapter describes the application and how modular software components can be used to assemble a blockchain solution. The chapter concludes with a design of the system architecture. The background to blockchain technology includes a description of the evolving nature due to communal, open software consortia and an accelerated prototyping of systems. Four recommendations are made in the chapter. These include the need to form consortia for prototyping applications, encouraging government involvement, the need for engagement with the open software development community, and the suggestion that systems should be designed to support Lean production. A final section offers a range of discussion topics on the current state of the technology and where to expect area of increased interest. These are summarized in three areas: Lean management, Industry 4.0 and smart cities, and topics around privacy and security.
TopIntroduction
Perspectives of The Research and a Summary Of The Contents Of The Chapter
This chapter describes the technology behind blockchains and how, in conjunction with a suite of interrelated modular components, they can be used for a variety of tasks in construction and engineering (C&E) projects (Darabseh & Martins, 2020; Yang, et al., 2020; Hargaden, et al., 2019). There are a number of applications of blockchains that, irregardless of skepticism (Perera, et al., 2020), and the difficulty in scaling-up in size, could provide advantages over current solutions. This is because blockchains provide something novel: the ability to hold critical data that, once written, are immutable, protected, can reside on a distributed network of computers. Immutability provides the data with authenticity, the use of distributed networks allows independence of a central hosting authority (Berg, et al., 2018; Zheng, et al., 2018; Pilkington, 2016), and security of valuable data is made possible by cryptography. Smart contracts, embedded in the blockchains, can help automate processes, most notably, payments. In other words, blockchains enable mutually distrustful parties to transact safely without the intervention of a trusted third party. This, most distinguishing attribute, is a mechanism that institutionalizes trust (Werbach, 2018; Berg, et al., 2017; Weber, et al., 2016; Anon., 2015b).
These features and capabilities are increasingly in demand as mobile arrays of interconnected devices produce volumes of data that can be valorized by artificial intelligence, big-data analytics, and advanced visual displays. Proponents of blockchain technology have been quick to propose applications to support concepts such as the Internet of Things (IoT) (Delgado-Mohatar, et al., 2020; Panarello, et al., 2018), Industry 4.0 (Lee, et al., 2019), smart cities (Swan, 2018; Huckle, et al., 2016), digital twins (Yaqoob, et al., 2020), and edge computing (Xiong, et al., 2018), and BIM. What all these concepts require is reliable machine to machine communications (Afanasev, et al., 2018) on a secure data-layer that is able to overcome the segmentation caused by multiple sources. It was the work of insightful and futuristic thinkers that envisioned the broader application of blockchains across industry (Al-Jaroodi & Mohamed, 2019), government and civil society (Swan, 2015). -
The novelty of the technology has prompted proposals in C&E for: energy management and carbon accounting (Petri, et al., 2020; Wang, et al., 2017), transport monitoring (Knirsch, et al., 2018), contract and document flow automation, and supply chain synchronization. The hope is that the use of blockchains can lead to improved project workflow, time and cost savings, increased transparency and trust amongst stakeholders (Turk and Klinc, 2017).
But there are impediments to the smooth adoption of this new technology, notably the difficulty in scaling up in size, in the management of the networks, and in getting the systems to function correctly in the first place. But there are significant trends that inspire continued interest in this area. Firstly, leading technology companies offer blockchain hosting and partnering solutions. Secondly, start-up companies are developing innovative technology that makes developing and deploying blockchains systems easier and finally, a growing community of enthusiast are collaborating to provide solutions.
For use in C&E projects, systems can be divided into two categories: (1) blockchains for holding critical data such as certificates, authorisations, payments and tokens and (2) blockchains optimised for enacting smart contracts within complex trading environments. Both of these categories would be classified as industrial blockchains. They use the same core engineering elements as those in cryptocurrencies such as Bitcoin (Nakamoto, 2008), but have added capabilities that allow for smart contracts and a choice of algorithms for ordering and confirming the authenticity of the data. The following sections will explain these features and describe how they work.
Key Terms in this Chapter
Permissioned ledger: Is a blockchain network where each entity or node is required to be a member of the network. Anonymous nodes are not allowed to connect.
Distributed Ledger Technology (DLT): Is the term given to the collection of services, interfaces, software, and associate systems that allow blockchains to be used in industrial settings.
Transactors: Can be either human or a device, for example a shipper delivering a package and registering the transaction with a smartphone, that sends a transaction proposal to the consensus and ordering algorithm.
Privacy: Is required by the chain transactors to conceal their identities on the network. While members of the network may examine the transactions, the transactions can’t be linked to the transactor without special privilege. Data as well as transaction details can also be held privately.
Orderer Nodes: Are specific nodes on the network that are tasked with ordering the transactions. They ensure the consistency of the blockchain and deliver the endorsed transactions to the peers of the network. The orders provide the Ordering Service that sort the transactions into blocks and then distributes these blocks to peers for validation. The ordering service is independent of the peer processes and orders transactions and in HLF, it supports modular implementations so that the system can be extended and configured.
World State Database: (also called the Current State ) is a data store that is permanently attached to the blockchain where the latest and most complete records of transactions are stored. It is more efficient to read and query the blockchain through the World State.
Consensus Algorithm: Is the process by which the members of a network determine which transaction get recorded onto the blockchain.
Transactions: Are the official term used to describe the addition of a record to a blockchain. Members cannot write directly but must submit transaction proposals to the consensus and ordering algorithm.
Query: Is a call (or invocation) to read from the blockchain ledger. In HLF, chaincode is used to unwrap the blockchain to read certain keys or other data. Queries do not change the ledger state, although the client application can choose to submit a read-only transaction for ordering, validation, and commit, to provide an auditable proof that the blockchain has been read.
Quorum: Is the minimum number of members of the cluster that need to affirm that a transaction is acceptable to write to the ledger. For networks with few members, the central authority may make up the majority vote for acceptance.
Organization: Is a collective term used to describe users who can read and write to the blockchain. They are also referred to as members and managed by the MSP, which defines how other members of the network may verify their digital signatures when transacting or reading the ledger access rights of identities within an MSP are governed by policies which are also agreed upon when the organization joins the network. There is no size limit to the organization if they have access to a Peer (the main trading point). If they exist, collections of organizations form a Consortium.
Block: Is the basic unit that describes how files are organized in a blockchain. Blocks contain an ordered set of transactions that are cryptographically linked to the preceding block, and in turn it is linked to subsequent blocks. Blocks are assembled by the ordering service and then validated and committed to the blockchain by peers that reside on nodes.
Membership Service Provider (MSP): Is a set of tasks within the system that provides credentials to clients, and peers that allow them to participate in a HLF network. HLF supports dynamic membership, where members, peers, and ordering service nodes can be added and removed without compromising the integrity of the network.
Genesis Block: Is defined as the first block on a chain and represents the configuration that initializes and defines the ordering service.
Certificate Authority (CA): Is a modular component of the DLT with the role of issuing encryption keys to network members and other users. The CA issues one root certificate to each member and one enrollment certificate to each authorized user. This should not be confused with using the blockchain to hold official certification by an authority.
Invoke: Is when a call is made via chaincode to alter the state (i.e. write) to the blockchain. This requires that the transaction is sent as a proposal to a Peer, which must be endorsed, ordered, and committed to become a permanent record.
Hyperledger Fabric: Is primarily aimed at industrial blockchains. It is a quickly evolving framework that contains commands and modules to allow the blockchains to be developed, evaluated, deployed, and initiated.
Channel: A name given to an enhanced feature of a DLT that allows a degree of privacy to exist within a subset of a larger trading network.
Smart Contract: A simple computer program that resides in compiled format within the block data structure across a peer-to-peer network that runs whenever the chain is re-written. A set of instructions in the form of a checklist, executes the instructions held in the blockchain.
Blockchain: A file linked in a block structure that takes the form of a sequential database. It is ubiquitous, immutable, and traceable, and can record transactions with transparent and trusted rules in a peer-to-peer network.
Certification: Is defined as secure data in the form of a signed document that is held on a blockchain. These records can have controlled access through multiple layers of cryptography.
Chaincode: Is an alternative name for smart contracts used in the Hyperledger Fabric framework. Using modular features of HFL, smart contracts can be programmed into the system in diverse ways, such as the client interface or through an associated database.
Permissioned Blockchain: Infrastructure that is based on a principle of modular architecture. Permissioned describes a DLT that has a controlled and limited membership. This allowed a great deal of flexibility in designing systems as it permits the separation of roles between the nodes in the infrastructure, execution of chaincode and a configurable consensus and membership service.
Validating Peers: All transactions must be validated by Peers. These are networked computer nodes owned either by one of the participant organizations or hosted by a professional service provider. Nodes hold a copy of the blockchains and are responsible for ensuring consensus used to validate transactions. Once validation is complete when all nodes receive an updated version of the blockchain.
Private Data: Are confidential information stored by peers on the blockchain but kept separate from other data. Access to this data is restricted to members with permission, while unauthorized organizations will only see a hash of the private data on the channel ledger as evidence of the transaction For an additional level of privacy, these hashes of private data go through the Ordering Service, which keeps it hidden from the Orderer.
Policies: Are part of the language used for constructing the layers of encryption in the data blockchain. They are used to control access to data and other resources in a blockchain network, notably who or who cannot read and write to a channer, evoke, query, or deploy chaincode. Policies are defined in the configuration files prior to deploying the network, setting up an ordering service or creating a channel. They can also be specified with instantiating chaincode.
Endorsement: Is defined as the process where specific peer nodes execute a chaincode transaction and return a proposal response to the client application. Endorsement is based on a policy that defines which peer nodes on a channel can execute transactions.
Custodian: This is the term used to describe the holder of the asset, receiving it from the Transactor.
Ledger: Is a document that contains records of transactions held in chronological sequence. In modern terms, a digital ledger is defined as containing two distinct parts: the blockchain and the Current State database (or World State). The term Distributed Ledger Technology (DLT) describes copies held by multiple computers (or nodes) across a network.
Peer: A network entity that maintains a ledger and runs chaincode containers in order to perform read/write operations to the ledger. Peers are owned and maintained by members and make up the principle nodes in a blockchain network. Peers host ledgers, chaincode and participate in consensus.