Towards a Theory of Glue

TL;DR

This paper introduces a formal framework for behavior composition in component-based systems, focusing on behavior types, composition operators, and memoryless glue operators to better understand separation of concerns.

Contribution

It defines behavior types and composition operators, illustrating them with classical models, and formalizes memoryless glue operators to enhance modular system design.

Findings

Behavior types and composition operators are formalized.

Memoryless glue operators are characterized.

Framework applies to classical models like LTS and Coalgebras.

Abstract

We propose and study the notions of behaviour type and composition operator making a first step towards the definition of a formal framework for studying behaviour composition in a setting sufficiently general to provide insight into how the component-based systems should be modelled and compared. We illustrate the proposed notions on classical examples (Traces, Labelled Transition Systems and Coalgebras). Finally, the definition of memoryless glue operators, takes us one step closer to a formal understanding of the separation of concerns principle stipulating that computational aspects of a system should be localised within its atomic components, whereas coordination layer responsible for managing concurrency should be realised by memoryless glue operators.