| Popis: |
We report on the progress made with the development of CAS-SCEL for what concerns its design principles and the identication of primitives (such as movement primitives or space abstraction primitives) and interaction patterns (such as broadcast communication or anonymous interaction) that are needed in the case studies and, more generally, in Collective Adaptive Systems (CAS) design. Our rst concern has been the identication of abstractions and linguistic primitives for collective adaptation, location modelling, knowledge handling, and system interaction and aggregation. To this purpose we have taken as starting point a number of exploratory formalisms that are based on, or have taken inspiration from PEPA and SCEL, two languages that partners of the project have developed in the past years and that have proved very successful in modelling adaptive systems (SCEL) and in supporting quantitative analysis (PEPA). We use four exploratory formalisms, StocS, PALOMA, PEPA-S and Stochastic-HYPE, with specic features that are each very interesting for CAS modelling and analysis and assess the impact of new primitives on CAS specication and verication, by considering a concrete scenario, inspired by the bike-sharing case study. Each of the exploratory languages has specic traits. One of the key features of StocS is the use of attribute-based communication that is a valuable alternative to broadcast or binary synchronisation that appear to be inappropriate in CAS and ts well with the notions of anonymity and dynamicity of CASs. PALOMA, instead, stresses the role of locations as attributes of agents; their communication abilities depend on their location, through a perception function and only agents who enable the appropriate reception action have the capability to receive the message. In PEPA-S heterogeneous populations of indistinguishable agents operating on a set of locations are considered. PEPA-S aims at distilling and studying the set interaction patterns that are typical of CASs. Like in PALOMA, in PEPA-S the ability of agents to communicate depends on their location. Stochastic HYPE aims at modelling three distinct types of behaviour: instantaneous events that happen as soon specic conditions are met, stochastic events with durations drawn from exponential distributions and continuous behaviour described by ODEs over systems variables. In this report, we rst present the general and desired features of modelling languages for CAS, then we use the four dierent formalisms to model and analyse the running example based on city bike sharing case study. Each language has a dedicated section that ends with an assessment with respect to the desired features introduced in the rst part of the report. A concluding section summarises our contribution and describes the road map for the second year of the project. |
