  The ubiquitous presence of smart devices along with advancements in
connectivity coupled with the elastic capabilities of cloud and edge systems
have nurtured and revolutionized smart ecosystems. Intelligent, integrated
cyber-physical systems offer increased productivity, safety, efficiency, speed
and support for data driven applications beyond imagination just a decade ago.
Since several connected devices work together as a coordinated unit to ensure
efficiency and automation, the individual operations they perform are often
reliant on each other. Therefore, it is important to control what functions or
activities different devices can perform at a particular moment of time, and
how they are related to each other. It is also important to consider additional
factors such as conditions, obligation or mutability of activities, which are
critical in deciding whether or not a device can perform a requested activity.
In this paper, we take an initial step to propose and discuss the concept of
Activity-Centric Access Control (ACAC) for smart and connected ecosystem. We
discuss the notion of activity with respect to the collaborative and
distributed yet integrated systems and identify the different entities involved
along with the important factors to make an activity control decision. We
outline a preliminary approach for defining activity control expressions which
can be applied to different smart objects in the system. The main goal of this
paper is to present the vision and need for the activity-centric approach for
access control in connected smart systems, and foster discussion on the
identified future research agenda.
