Elisa Gonzalez Boix

AmbientTalk: Object-oriented Event-driven Programming in Mobile Ad hoc Networks

In this paper, we describe AmbientTalk: a domain- specific language for orchestrating service discovery and composition in mobile ad hoc networks. AmbientTalk is a distributed object-oriented language whose actor-based, event-driven concurrency model makes it highly suitable for composing service objects across a mobile network. The language is a so-called ambient-oriented programming language which treats network partitions as a normal mode of operation. We describe AmbientTalks object model, concurrency model and distributed communication model in detail. We also highlight influences from other languages and middleware that have shaped AmbientTalks design.

Flocks: enabling dynamic group interactions in mobile social networking applications

Mobile social networking applications enable end-users to interact on the move. Current applications model user groups as simple lists which have to be manually enumerated. This representation is both unsuitable and inefficient for group interactions: due to the openness and the mobility to which these applications are exposed, the contents of such lists are likely to change frequently. Updating the lists manually while interacting with users quickly becomes impractical. In this paper, we introduce an alternative representation for user groups named flocks. A flock represents a loosely-defined user group in terms of an intensional description. The flock content is implicitly updated when changes occur, e.g. the userss location. Flocks have group interaction provisions based on asynchronous message passing. Benchmarks indicate that flocks can be implemented efficiently by exploiting structure in their definitions. We present the flock abstraction and its implementation as the basis of a new distributed framework called Urbiflock.

AmbientTalk: programming responsive mobile peer-to-peer applications with actors

Abstract The rise of mobile computing platforms has given rise to a new class of applications: mobile applications that interact with peer applications running on neighbouring phones. Developing such applications is challenging because of problems inherent to concurrent and distributed programming, and because of problems inherent to mobile networks, such as the fact that wireless network connectivity is often intermittent, and the lack of centralized infrastructure to coordinate the peers. We present AmbientTalk, a distributed programming language designed specifically to develop mobile peer-to-peer applications. AmbientTalk aims to make it easy to develop mobile applications that are resilient to network failures by design. We describe the language׳s concurrency and distribution model in detail, as it lies at the heart of AmbientTalk׳s support for responsive, resilient application development. The model is based on communicating event loops, itself a descendant of the actor model. We contribute a small-step operational semantics for this model and use it to establish data race and deadlock freedom.

Orchestration support for participatory sensing campaigns

In this paper we argue the need for orchestration support for participatory campaigns to achieve campaign quality, and automatisation of said support to achieve scalability, both issues contributing to stakeholder usability. This goes further than providing support for defining campaigns, an issue tackled in prior work. We provide a formal definition for a campaign by extracting commonalities from the state of the art and expertise in organising noise mapping campaigns. Next, we formalise how to ensure campaigns end successfully, and translate this formal notion into an operational recipe for dynamic orchestration. We then present a framework for automatising campaign definition, monitoring and orchestration which relies on workflow technology. The framework is validated by re-enacting several campaigns previously run through manual orchestration and quantifying the increased efficiency.

Citizen-friendly participatory campaign support

Participatory sensing, which appropriates wearable devices such as mobile phones to enable ad-hoc, person-centric mobile sensing networks, has the potential of delivering datasets with high spatio-temporal granularity. We argue that to obtain such datasets the concept of a participatory campaign, a recipe for gathering data to answer a particular concern, is essential, and that technological support for organising such campaigns is currently lacking. Campaign support is crucial to ensure that a dataset of adequate quality is gathered to study the concern under consideration, and additionally, to empower communities by providing them with a tool to answer local concerns and set up grassroots sensing actions without having to wait for an institutionalised action to take place. In this article we present a proof-of-concept architecture for participatory campaigns. The latter is built upon a formal definition of a campaign and the description of a campaign lifecycle, both of which are distilled out of earlier expertise with and related work on organising participatory sensing campaigns.

REME-D: a reflective epidemic message-oriented debugger for ambient-oriented applications

Debuggers are an integral part, albeit often neglected, of the development of distributed applications. Ambient-oriented programming (AmOP) is a distributed paradigm for applications running on mobile ad hoc networks. In AmOP the complexity of programming in a distributed setting is married with the network fragility and open topology of mobile applications. To our knowledge, there is no comprehensive debugging approach that tackles both these issues. In this paper we present REME-D, an online debugger that integrates techniques from distributed debugging (event-based debugging, message breakpoints) and proposes facilities to deal with ad hoc, fragile networks -- epidemic debugging, and support for frequent disconnections. A prototype for REME-D is implemented for the AmbientTalk language using the meta-actor protocol provided by AmbientTalk to implement its features.

Ambient-Oriented exception handling

Writing ambient-oriented software for mobile devices connected through wireless network connections provides new challenges in the field of exception handling. It involves dealing with issues such as asynchronous communication, moving hardware and software, only to name a few. Building on an analysis of the fundamental differences between mobile networks and their stationary counterparts, this paper establishes a set of criteria for an ambient-oriented exception handling mechanism. We subsequently present ambient conversations, a novel distributed exception handling mechanism that adheres to the prescribed criteria, and describe its realisation in the experimental ambient-oriented programming language AmbientTalk.

Programming mobile context-aware applications with TOTAM

In tuple space approaches to context-aware mobile systems, the notion of context is defined by the presence or absence of certain tuples in the tuple space. Existing approaches define such presence either by collocation of devices holding the tuples or by replication of tuples across all devices. We show that both approaches can lead to an erroneous perception of context. Collocation ties the perception of context to network connectivity which does not always yield the expected result. Tuple replication can cause that a certain context is perceived even if the device has left the context a long time ago. We propose a tuple space approach in which tuples themselves carry a predicate that determines whether they are in the right context or not. We present a practical API for our approach and show its use by means of the implementation of various mobile applications. Benchmarks show that our approach can lead to a significant increase in performance compared to other approaches.

Distributed debugging for mobile networks

Debuggers are an integral part, albeit often neglected, of the development of distributed applications. Ambient-oriented programming (AmOP) is a distributed paradigm for applications running on mobile ad hoc networks. In AmOP the complexity of programming in a distributed setting is married with the network fragility and open topology of mobile applications. To our knowledge, there is no debugging approach that tackles both these issues. In this paper we argue that a novel kind of distributed debugger that we term an ambient-oriented debugger, is required. We present REME-D (read as remedy), an online ambient-oriented debugger that integrates techniques from distributed debugging (event-based debugging, message breakpoints) and proposes facilities to deal with ad hoc, fragile networks - epidemic debugging, and support for frequent disconnections.

Urbiflock: An experiment in dynamic group management in Pervasive social applications

Pervasive social applications are applications that enable end users to interact and share information on the move. In these applications, the concept of a user group plays a central role as it models the users social networks. Most pervasive social applications today model these user groups as simple lists of users that have to be manually managed by the user to reflect the changes in a frequently changing context. Managing user groups in current frameworks is complicated because of three main reasons. There is a lack of abstractions (i) to discover users on the move, (ii) to organize these users in composable context-aware user groups, and (iii) to manage the communication between the users and groups of users. Our research focuses on providing proper abstractions to deal with the specific characteristics of user groups in pervasive social applications. In this paper we describe Urbiflock, a framework which aids the programmer in managing the complexity of implementing such dynamic user groups. Furthermore, we describe a messaging system called Guanotes which has been developed by means of our framework and exploits dynamic user groups to enable context-aware message propagation among mobile users.