COAST: An Architectural Style for Decentralized On-Demand Tailored Services

Decentralized systems are systems-of-systems whose services are governed by two or more separate organizations under distinct spheres of authority. Coordinated evolution of the various elements of a decentralized system may be difficult, if not impossible, as individual organizations evolve their service offerings in response to organization- and service-specific pressures, including market demand, technology, competitive and cooperative interests, and funding. Consequently, decentralized services offer unique challenges for evolution and adaptation that reach well beyond any one single organizational boundary. However, client-driven service customization and tailoring is a powerful tool for meeting conflicting, independent client demands in an environment where disorderly and uneven service evolution predominates. To this end, we contribute an architectural style, COmputAtional State Transfer (COAST), designed to provide extensive, safe, and secure client-directed customization of decentralized services. COAST combines mechanisms from software architecture, cryptography, security, and programming languages, granting application architects flexible provisioning of their core services and assets while protecting those services and assets from attack and misuse.