Danilo Pianini ; Roberto Casadei ; Mirko Viroli ; Stefano Mariani ; Franco Zambonelli - Time-Fluid Field-Based Coordination through Programmable Distributed Schedulers

lmcs:7029 - Logical Methods in Computer Science, November 25, 2021, Volume 17, Issue 4 - https://doi.org/10.46298/lmcs-17(4:13)2021
Time-Fluid Field-Based Coordination through Programmable Distributed SchedulersArticle

Authors: Danilo Pianini ; Roberto Casadei ; Mirko Viroli ; Stefano Mariani ; Franco Zambonelli

    Emerging application scenarios, such as cyber-physical systems (CPSs), the Internet of Things (IoT), and edge computing, call for coordination approaches addressing openness, self-adaptation, heterogeneity, and deployment agnosticism. Field-based coordination is one such approach, promoting the idea of programming system coordination declaratively from a global perspective, in terms of functional manipulation and evolution in "space and time" of distributed data structures called fields. More specifically regarding time, in field-based coordination (as in many other distributed approaches to coordination) it is assumed that local activities in each device are regulated by a fair and unsynchronised fixed clock working at the platform level. In this work, we challenge this assumption, and propose an alternative approach where scheduling is programmed in a natural way (along with usual field-based coordination) in terms of causality fields, each enacting a programmable distributed notion of a computation "cause" (why and when a field computation has to be locally computed) and how it should change across time and space. Starting from low-level platform triggers, such causality fields can be organised into multiple layers, up to high-level, collectively-computed time abstractions, to be used at the application level. This reinterpretation of time in terms of articulated causality relations allows us to express what we call "time-fluid" coordination, where scheduling can be finely tuned so as to select the triggers to react to, generally allowing to adaptively balance performance (system reactivity) and cost (resource usage) of computations. We formalise the proposed scheduling framework for field-based coordination in the context of the field calculus, discuss an implementation in the aggregate computing framework, and finally evaluate the approach via simulation on several case studies.

    Volume: Volume 17, Issue 4
    Published on: November 25, 2021
    Accepted on: September 22, 2021
    Submitted on: December 30, 2020
    Keywords: Computer Science - Logic in Computer Science,Computer Science - Distributed, Parallel, and Cluster Computing,I.2.11,D.1.3,I.2.5,D.3.1

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