David Metcalf

The Hyperledger Project

The Hyperledger Project is a Linux Foundation initiative to develop an open source ecosystem of blockchain development. The Linux Foundation aims to create an environment in which communities of software developers and companies meet and coordinate to build blockchain frameworks. Hyperledger itself is not another cryptocurrency, but rather an open hub for enterprise-grade blockchain projects to incubate and mature through all stages of development and commercialization. In this chapter, we talk about the current state of the Hyperledger Project, with a focus on the currently incubating projects, a summary of the project scope being implemented, and a review of the comprehensive set of technologies involved in creating an open source enterprise-grade blockchain.

Foundations of Blockchain

The blockchain is a decentralized data structure with internal consistency maintained through consensus reached by all the users on the current state of the network. It’s an enabling technology that resolved the Byzantine generals’ problem (message communication between untrusted parties) and opened up a new horizon of possibilities for trustless transactions and exchange of information. If the Internet democratized the peer-to-peer exchange of information, then the blockchain has democratized the peer-to-peer exchange of value. We begin this chapter by exploring how transactions work between users on the Bitcoin network. This entails a technical discussion of structures of a block and a transaction. We then dive into the role of wallets and user addresses. After talking about wallets, we shift our focus to simple payment verification (SPV) implemented in the Bitcoin network. SPV allows us to understand why blocks have a peculiar structure and more important, how the Bitcoin network can retain efficiency despite the network scaling at a high rate. Finally, we conclude our discussion by talking about hard and soft forks in the blockchain. We present the implications of forks in the context of forward compatibility for merchants and users involved in running the Bitcoin-core code.

Blockchain in Health Care

The health care sector is a

Technological Revolutions and Financial Capital

3 trillion industry, and about

The Gold Rush: Mining Bitcoin

1 trillion of it goes to waste annually. Care coordination is becoming more complex as chronic conditions in the aging population continue to rise. In many instances, the technology available to health care providers is not adequate enough to capture all aspects of the care being provided. The result is a rugged transfer of information between parties that ultimately reduces the quality of care being provided to patients. This is largely due to providers having legacy systems, lack of integration with non-vendor-specific technologies, paper-based medical records, and a lack of horizontal transfer between allied health care professions. Hospitals are investing a considerable amount of resources into duplicating the work that can be completed by a sophisticated technology infrastructure, and amplifying the inefficiency of using poorly designed systems. In this use case, we discuss the payer–provider–patient model in the context of the incentives and services each provides and how this model is likely to change in the near future. We then introduce how blockchain can integrate into tracking the workflow of a patient from the first visit to final diagnosis and treatment plan. We introduce two new features that blockchain integration can enable: hot switching of components and medical data curation. Finally, we conclude by discussing waste management in health care and the efforts by Capital One + Gem to increase the economic output.

Recent Developments in Blockchain

The global financial markets are undergoing a drastic change that makes it clear that without innovation most business and financial models could soon become obsolete. A recent overview of the global financial system described the current system as a:

Ethereum Tokens: High-Performance Computing

Mining is a key operational concept in understanding how the Bitcoin protocol operates. It refers to a decentralized review process performed on each block of the blockchain to reach consensus without the need for a central authority to provide trust. In other words, mining is the computational equivalent of peer review in a decentralized environment where neither party involved trusts the other. Then, we integrate the concepts of block target values and network difficulty with mining and how mining has evolved to keep up with the increasing difficulty. This will lead us further into talking about the types of hardware mining that have recently been developed. We end the chapter with an analysis of startups that began selling dedicated hardware for mining, leading to the Bitcoin mining arms race and their eventual failure.

The DAO Hacked

In this chapter, we focus on three new technologies that have significantly advanced our understanding of blockchain-enabled applications and opened up several new avenues for research. We begin our discussion with EOS, an Ethereum competitor built with an OS inspired architecture and platform-support design philosophy. It uses a new consensus mechanism called delegated proof-of-stake to enable rapid transaction verification and a continuous cycle of voting for delegates that support the network. The message passing protocols implemented in EOS are very advanced, allowing automated response handlers and action triggers on message delivery. They make up most of the smart contract system. There is also support for parallel lockless execution of smart contract instructions across the network, massively reducing latency in communication and state updates.

Blockchain in Science

In the Ethereum ecosystem, transfer of value between users is often realized by the use of tokens that represent digital assets. Ether is the default token and the de facto currency used for transactions and initializing smart contracts on the network. Ethereum also supports the creation of new kinds of tokens that can represent any commonly traded commodities as digital assets. All tokens are implemented using the standard protocol, so the tokens are compatible with any Ethereum wallet on the network. The tokens are distributed to users interested in the given specific use case through an ICO. In this chapter, we focus our attention on tokens created for a very specific use case: high-performance computing (HPC). More precisely, we discuss a model of distributed HPC where miners offer computational resources for a task and get rewarded in some form of Ethereum tokens.

Behold the Dreamers

Here, we want to highlight a historic moment leading to the creation of the first DAO, and how it eventually got hacked. Our discussion begins with a fresh perspective on decentralized organizations from Buterin, and leads into the story of Slock.it, the company at the heart of the DAO revolution. Then, we present some code that made The DAO dysfunctional: pieces of the smart contract relevant to the vulnerability, the conditions that allowed repetitive withdrawals from The DAO, and the exploit itself. We conclude the chapter by talking about the consequences of this hack: the debate about hard vs. soft forks, and the creation of Ethereum Classic.