summarize this BACKGROUND AND CASE STUDY in your language.

This section provides background information on the ISO/IEC/IEEE 42010 standard, some more information on situational awareness, and an overview of the SCUNA case study.

A. Background on 42010 Architecture Description

In this paper, we build upon the conceptual foundations of the ISO/IEC/IEEE 42010:2011, Systems and software engineering Architecture description [7] standard, to investigate the essential elements of architecture description for situational aware cyber-physical systems (SiA-CPS).

The standard addresses architecture description (AD), that is, the practices of recording software, system, and enterprise architectures so that architectures can be understood, doc- umented, analyzed and realized. Architecture descriptions take on many forms, from informal to rigorously specified models.

The content model for an architecture description is illus- trated in Figure 1. Architecture viewpoint is a fundamental building block representing common ways of expressing recurring architectural concerns reusable across projects and organizations. It encapsulates model kinds framing particular concerns for a particular audience of system stakeholders. The concerns determine what the model kinds must be able to express: e.g., security, reliability, cost, etc. A model kind determines the notations, conventions, methods and techniques to be used. Viewpoints, defining the contents of each architecture view, are built up from one or more model kinds and correspondence rules linking them together to maintain consistency.

B. Situational Awareness

Situational Awareness (SiA) refers to a persons awareness of what is going on in her surroundings, the meaning of these surroundings, and using this information to decide and act.

A theoretical model of SiA has been presented by Endsley in [8]. His model describes SiA states and illustrates three stages of SiA formation: perception (i.e., the perception of the status, attributes, and dynamics of relevant elements in the environment), comprehension (including pattern recog- nition, interpretation, and evaluation), and projection (i.e., the ability to project the future actions of the elements in the environment). SiA is also framed within the OODA (Observe, Orient, Decide, Act) loop [9].

The growth of the market is described in the report World Situational Awareness Systems (SAS) - Market Opportunities and Forecasts, 2015-20222, where the market is projected to garner USD 32,6 billion by 2022. The reasons are many, ranging from governments initiatives for disaster management, to increasing interest in public safety, new technologies for data monitoring and collection, and the evolution of the Smart Cities concept and related.

C. The SCUNA case study

The SCUNA (Smart Card at the UNiversity of lAquila) project consists in using a smart card and other IoT technolo- gies to improve the quality of the working life of students, professors, and staff. The main services are related to the access control to rooms, laboratories, and parking lots; to the monitoring of open and closed spaces; to the emergency exit management in case of safety cases such as earthquakes and fire; to the support to people with disabilities. The full list of services can be found at https://goo.gl/zyGpe1. We here focus, instead, on a few SiA services that we will use in the rest of this paper:

conditional access due to roles: the access of an actor to certain rooms is conditional to the presence of other actors in the room (e.g., a student may enter a laboratory only if a technician is already in);

university space monitoring: the internal and external spaces are monitored for temperature, load, available seats, and other variables;

conditional access due to the space state: the access to a room is granted only if the room state (e.g., the number of available seats) are granted (e.g., while a student may have access to a classroom, if the latter is too full, the student will not be granted access). A number of people in the room can be monitored through people counters, cameras, or other IoT devices.