1Roy Thomas Fielding's thesis Architectural Styles and the Design of 2Network-based Software Architectures describes Representational State Transfer 3which comprises several core concepts: 4- Resource: A conceptual mapping to one or more entities. 5- Representation: An instance of a resource at a given point in time. 6 7Async::REST models these abstractions as closely and practically as possible and 8serves as a basis for building asynchronous web clients. 9