Marco Mamei

Programming pervasive and mobile computing applications: The TOTA approach

Pervasive and mobile computing call for suitable middleware and programming models to support the activities of complex software systems in dynamic network environments. In this article we present TOTA (“Tuples On The Air”), a novel middleware and programming approach for supporting adaptive context-aware activities in pervasive and mobile computing scenarios. The key idea in TOTA is to rely on spatially distributed tuples, adaptively propagated across a network on the basis of application-specific rules, for both representing contextual information and supporting uncoupled interactions between application components. TOTA promotes a simple way of programming that facilitates access to distributed information, navigation in complex environments, and the achievement of complex coordination tasks in a fully distributed and adaptive way, mostly freeing programmers and system managers from the need to take care of low-level issues related to network dynamics. This article includes both application examples to clarify concepts and performance figures to show the feasibility of the approach

Extracting urban patterns from location-based social networks

Social networks attract lots of new users every day and absorb from them information about events and facts happening in the real world. The exploitation of this information can help identifying mobility patterns that occur in an urban environment as well as produce services to take advantage of social commonalities between people. In this paper we set out to address the problem of extracting urban patterns from fragments of multiple and sparse people life traces, as they emerge from the participation to social network. To investigate this challenging task, we analyzed 13 millions Twitter posts (3 GB) of data in New York. Then we test upon this data a probabilistic topic models approach to automatically extract urban patterns from location-based social network data. We find that the extracted patterns can identify hotspots in the city, and recognize a number of major crowd behaviors that recur over time and space in the urban scenario.

Cofields: a physically inspired approach to motion coordination

As computing becomes increasingly pervasive, autonomous computers are going to be embedded in everyday objects in our physical environment. In such scenarios, mobility itself will be pervasive. Mobile users, mobile devices, computer-enabled vehicles, and mobile software components will define a dynamic, networked world in which a large set of autonomous components will interact with each other to orchestrate their activities. We focus on the problem of coordinating autonomous agents movements in a distributed environment. Orchestrating mobile autonomous agents can take inspiration from the laws of physics. Agents movements could be driven by locally perceived computational force fields, or cofields, generated by the agents themselves and propagated through an embedded infrastructure.

Pervasive pheromone-based interaction with RFID tags

Despite the growing interest in pheromone-based interaction to enforce adaptive and context-aware coordination, the number of deployed systems exploiting digital pheromones to coordinate the activities of situated autonomous agents is still very limited. In this article, we present a simple low-cost and general-purpose implementation of a pheromone-based interaction mechanism for pervasive environments. This is realized by making use of RFID tags to store digital pheromones and by having humans or robots spread/sense pheromones by properly writing/reading RFID tags populating the surrounding physical environment. We exemplify and evaluate the effectiveness of our approach via an application for object-tracking. This application allows robots and humans to find forgotten-somewhere objects by following pheromones trails associated with them. In addition, we sketch further potential applications of our approach in pervasive computing scenarios, discuss related work in the area, and identify future research directions.

EXPERIMENTS OF MORPHOGENESIS IN SWARMS OF SIMPLE MOBILE ROBOTS

In this paper, we focus on the problem of having a multitude of very simple mobile robots self-organize their relative positions so as to obtain a variety of spatial configurations. The problem has a variety of applications in mobile robotics, modular robots, sensor networks, and computational self-assembly. The approach we investigate in this paper attempts at minimizing the local capability of robots and at verifying how and to what extent a variety of global shapes can be obtained by exploiting simple self-organizing algorithms and emergent behaviors. Several experiments are reported showing the effectiveness of the approach.

Self-aware Pervasive Service Ecosystems

Here we present the overall objectives and approach of the SAPERE (“Self-aware Pervasive Service Ecosystems”) project, focussed on the development of a highly-innovative nature-inspired framework, suited for the decentralized deployment, execution, and management, of self-aware and adaptive pervasive services in future network scenarios.

Co-fields: towards a unifying approach to the engineering of swarm intelligent systems

Swarm intelligent systems, in which the paths to problem solving emerge as the result of interactions between simple autonomous components (agents or ants) and between them and their environment, appear very promising to develop robust and flexible software application. However, the variety of swarm-based approaches that have been proposed so far still lacks a common modeling and engineering methodology. In the attempt to overcome this problem, this paper presents a general coordination methodology in which swarms components are simply driven by abstract computational force fields (Co-Fields), generated either by agents, or by the environment. By having agents be driven in their activities by such fields, globally coordinated behaviors can naturally emerge. Although this model still does not offer a complete engineering methodology, it can provide a unifying abstraction for swarm intelligent systems and it can also be exploited to formalize these systems in terms of dynamical systems whose behavior can be described via differential equations. Several example of swarm systems modeled with Co-Fields are presented to support our thesis.

Emergence and control of macro-spatial structures in perturbed cellular automata, and implications for pervasive computing systems

Predicting the behavior of complex decentralized pervasive computing systems before their deployment in a dynamic environment, as well as being able to influence and control their behavior in a decentralized way, will be of fundamental importance in the near future. In this context, this paper describes the general behavior observed in a large set of asynchronous cellular automata when external perturbations influence the internal activities of cellular automata cells. In particular, we observed that stable macrolevel spatial structures emerge from local interactions among cells, a behavior that does not emerge when cellular automata are not perturbed. Similar sorts of macrolevel behaviors are likely to emerge in the context of pervasive computing systems and need to be studied, controlled, and possibly fruitfully exploited. On this basis, the paper also reports the results of a set of experiments, showing how it is possible to control, in a decentralized way, the behavior of perturbed cellular automata, to make any desired patterns emerge.

Programming stigmergic coordination with the TOTA middleware

Stigmergic coordination has received a growing attention in the past few years. In fact, by decoupling interacting agents via the mediation of an active environment, stigmergy promotes the definition of robust and adaptive multiagent systems. However, beside a large amount of scientific studies, the problem of defining usable and general-purpose tools to program stigmergy-coordinated multiagent systems is still open. In this context, this paper shows how the TOTA middleware can be effectively exploited to support a variety of stigmergy-based coordination activities. The key idea in TOTA is to rely on a simple API for injecting tuple-based information in a network. have it propagate and/or evaporate accordingly to application-specific policies, and have it locally sensed by application agents. Application examples are presented to show that TOTA can promote a simple programming of a variety of different types of stigmergic interactions, in a variety of operational environments.

Mechanisms for environments in multi-agent systems: Survey and opportunities

The environment has been recognized as an explicit and exploitable element to design multi-agent systems (MAS). It can be assigned a number of responsibilities that would be more difficult to design with the sole notion of agents. To support the engineering of these responsibilities, we identify a set of mechanisms that offer solutions to software designers. We describe the mechanisms, their usage in representative projects, and potential opportunities for further research and applications. The purpose of this article is to clarify the notion of environment in terms of mechanisms, from their abstract description to their practical exploitation. Mechanisms are expected to provide agent-based software designers with a set of design elements to build MAS that take advantage of the environment.