Factors that Impact Blockchain Scalability

Blockchain systems (more precisely Distributed Ledger Technologies(DLTs)) represent a different digital ecosystem compared with traditional computer systems. One major difference are the performance and scalability factors which will be discussed and analytically investigated in this paper. Indoing so, we provide guidance for defining a research agenda focusing on the investigation of the crucial role of scalability for DLT systems. System performance - measured in terms of (1) consensus response time (blockchain network latency or time to convergence/agreement); (2) number of transactionsper second or throughput, and (3) computing (and power) resources consumed - can be understood by considering the design dimensions of a DLT system, namely: (i) the type of DLT system needed from a requirements perspectivewhich in turn determines; (ii) the complexity of the consensus protocol used; (iii) the topography of the anticipated traffic flow on the network; (iv) the performance and complexity of the domain-specific language that implementssmart contracts; and (v) by the anticipated growth in size and complexity of the distributed ledger itself.Blockchain systems (more precisely Distributed Ledger Technologies(DLTs)) represent a different digital ecosystem compared with traditional computer systems. One major difference are the performance and scalability factors which will be discussed and analytically investigated in this paper. Indoing so, we provide guidance for defining a research agenda focusing on the investigation of the crucial role of scalability for DLT systems. System performance - measured in terms of (1) consensus response time (blockchain network latency or time to convergence/agreement); (2) number of transactionsper second or throughput, and (3) computing (and power) resources consumed - can be understood by considering the design dimensions of a DLT system, namely: (i) the type of DLT system needed from a requirements perspectivewhich in turn determines; (ii) the complexity of the consensus protocol used; (iii) the topography of the anticipated traffic flow on the network; (iv) the performance and complexity of the domain-specific language that implementssmart contracts; and (v) by the anticipated growth in size and complexity of the distributed ledger itself

Atomic Appends: Selling Cars and Coordinating Armies with Multiple Distributed Ledgers

The various applications using Distributed Ledger Technologies (DLT) or blockchains, have led to the introduction of a new "marketplace" where multiple types of digital assets may be exchanged. As each blockchain is designed to support specific types of assets and transactions, and no blockchain will prevail, the need to perform interblockchain transactions is already pressing. In this work we examine the fundamental problem of interoperable and interconnected blockchains. In particular, we begin by introducing the Multi-Distributed Ledger Objects (MDLO), which is the result of aggregating multiple Distributed Ledger Objects - DLO (a DLO is a formalization of the blockchain) and that supports append and get operations of records (e.g., transactions) in them from multiple clients concurrently. Next we define the AtomicAppends problem, which emerges when the exchange of digital assets between multiple clients may involve appending records in more than one DLO. Specifically, AtomicAppend requires that either all records will be appended on the involved DLOs or none. We examine the solvability of this problem assuming rational and risk-averse clients that may fail by crashing, and under different client utility and append models, timing models, and client failure scenarios. We show that for some cases the existence of an intermediary is necessary for the problem solution. We propose the implementation of such intermediary over a specialized blockchain, we term Smart DLO (SDLO), and we show how this can be used to solve the AtomicAppends problem even in an asynchronous, client competitive environment, where all the clients may crash

GeoCoin:supporting ideation and collaborative design with location-based smart contracts

Design and HCI researchers are increasingly working with complex digital infrastructures, such as cryptocurrencies, distributed ledgers and smart contracts. These technologies will have a profound impact on digital systems and their audiences. However, given their emergent nature and technical complexity, involving non-specialists in the design of applications that employ these technologies is challenging. In this paper, we discuss these challenges and present GeoCoin, a location-based platform for embodied learning and speculative ideating with smart contracts. In collaborative workshops with GeoCoin, participants engaged with location-based smart contracts, using the platform to explore digital `debit' and `credit' zones in the city. These exercises led to the design of diverse distributed-ledger applications, for time-limited financial unions, participatory budgeting, and humanitarian aid. These results contribute to the HCI community by demonstrating how an experiential prototype can support understanding of the complexities behind new digital infrastructures and facilitate participant engagement in ideation and design processes