Models and Languages for Overlay Networks

Abstract

Implementing overlay software is non-trivial. In current projects, overlays or frameworks are built on top of low-level networking abstractions. This leaves the implementation of topologies, their maintenance and optimisation strategies, and the routing entirely to the developer. Consequently, topology characteristics are woven deaply into the source code and the tight coupling with low-level frameworks prevents code reuse when other frameworks prove a better match for the evolving requirements.

This paper presents OverML, a high-level overlay specification language that is independent of specific frameworks. The underlying system model, named “Node Views”, abstracts from low-level issues such as I/O and message handling and instead moves ranking nodes and selecting neighbours into the heart of the overlay software development process. The abstraction decouples maintenance components in overlay software, considerably reduces their need for framework dependent source code and enables their generic, configurable implementation in pluggable EDSM frameworks.