Organic and Hierarchical Concentric Layouts for Distributed System Visualization

Distributed systems, due to their inherent complexity and nondeterministic nature, are programmed using high-level abstractions, such as processes, actors, ambients, agents, or services. There is a need to provide tools which allow developers to better understand, test, and debug distributed systems. OverView is a software toolkit which allows online and offline visualization of distributed systems through the concepts of entities and containers, which preserve the abstractions used at the programming level and display important dynamic properties, such as temporal (that is, when entities are created and deleted), spatial (that is, entity location and migration events) and relational (that is, entity containment or communication patterns). In this paper, we introduce two general layout mechanisms to visualize distributed systems: a hierarchical concentric layout that places containers and entities in a ring of rings, and an organic layout that uses the dynamic properties of the system to co-locate entities. We define visualization quality metrics such as intuitiveness, scalability, and genericity, and use them to evaluate the visualization layouts for several application communication topologies including linked lists, trees, hypercubes, and topologies arising from structured overlay networks such as Chord rings.