Towards Reusable Smart Contracts for Trustworthy Collaborative Processes

In collaborative environments, where enterprises interact each other's without a centralised authority that ensures trust among them, the ability of providing cross-organisational services must be enabled also between mutually untrusting participants. Blockchain platforms and smart contracts have been proposed to implement trustworthy collaborative processes. However, current solutions are constrained to a speci fic blockchain technology and deployed on-chain the whole process, thus increasing the execution costs of smart contracts on permissionless blockchains. In this paper, we propose an approach that includes criteria to identify trust-demanding objects and activities in collaborative processes, a model to describe smart contracts in a technology-independent way and guidelines to deploy them on a blockchain. To this aim, a threelayered model is used to describe: (i) the collaborative process, represented in BPMN, where the business expert is supported to add annotations that identify trust-demanding objects and activities; (ii) Abstract Smart Contracts, based on trust-demanding objects and activities only and independent from any blockchain technology; (iii) Concrete Smart Contracts, that implement abstract ones and are deployed over a speci fic blockchain. Flexibility and cost reduction brought by approach are discussed in the context of a case study on remote monitoring services for the digital factory.