Yggdrasil: An Artifact-Based Framework for Hypermedia Multi-Agent Systems

Recent years have brought renewed interest in Web-based Multi-agent Systems (MAS), primarily motivated by progress in the Web of Things, Distributed Knowledge Graphs, and Generative AI. Central to these developments is the flexible, autonomous use of hypermedia—for example, to discover knowledge, invoke device functionality, or use tools. However, existing frameworks for Web-based MAS typically lack support for working with hypermedia abstractions and controls. To fill this gap, this chapter presents a model and framework for hypermedia-based MAS. Our specific focus is on the environment as a first-class abstraction in MAS: agents are situated and embodied in a distributed hypermedia environment that (i) provides them with a uniform abstraction of the system and (ii) is instrumented with tools and resources they can discover and use to achieve their goals. Given a single entry point into the hypermedia environment, agents are enabled to “arrive-and-operate”: they use their prior knowledge and experience to achieve their goals by browsing hypermedia and exploiting action possibilities discovered at run time—mimicking how humans are supported by well-designed hypermedia environments today. We illustrate our approach through a demonstrator and discuss its benefits and drawbacks against an equivalent implementation without hypermedia.