Wolfgang De Meuter

Ambient-Oriented programming in ambienttalk

A new field in distributed computing, called Ambient Intelligence, has emerged as a consequence of the increasing availability of wireless devices and the mobile networks they induce. Developing software for mobile networks is extremely hard in conventional programming languages because the network is dynamically demarcated. This leads us to postulate a suite of characteristics of future Ambient-Oriented Programming languages. A simple reflective programming language, called AmbientTalk, that meets the characteristics is presented. It is validated by implementing a collection of high level language features that are used in the implementation of an ambient messenger application.

Ambient-oriented programming in ambientTalk

A new field in distributed computing, called Ambient Intelligence, has emerged as a consequence of the increasing availability of wireless devices and the mobile networks they induce. Developing software for such mobile networks is extremely hard in conventional programming languages because of new distribution issues related to volatile network connections, dynamic network topologies and partial failures.

Ambient-oriented programming

A new field in distributed computing, called Ambient In-telligence, has emerged as a consequence of the increasing availability of wireless devices and the mobile networks they induce. Developing software for such mobile networks is extremely hard in conventional programming languages because the network is dynamically defined. This hardware phenomenon leads us to postulate a suite of characteristics of future Ambient-Oriented Programming languages. A simple re ective programming language kernel, called AmbientTalk, that meets these characteristics is subsequently presented. The power of the re ective kernel is illustrated by using it to conceive a collection of high level tentative ambient-oriented programming language features.

Context-aware tuples for the ambient

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 those tuples across all devices. We show that both approaches can lead to an erroneous perception of context. The former ties the perception of context to network connectivity which does not always yield the expected result. The latter causes context to be perceived even if a device has left that 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 a mobile game.

A Leasing Model to Deal with Partial Failures in Mobile Ad Hoc Networks

In mobile ad hoc networks (MANETs) many partial failures are the result of temporary network partitions due to the intermittent connectivity of mobile devices. Some of these failures will be permanent and require application-level failure handling. However, it is impossible to distinguish a permanent from a transient failure. Leasing provides a solution to this problem based on the temporal restriction of resources. But to date no leasing model has been designed specifically for MANETs. In this paper, we identify three characteristics required for a leasing model to be usable in a MANET, discuss the issues with existing leasing models and then propose the leased object references model, which integrates leasing with remote object references. In addition, we describe an implementation of the model in the programming language AmbientTalk. Leased object references provide an extensible framework that allows programmers to express their own leasing patterns and enables both lease holders (clients) and lease grantors (services) to deal with permanent failures.

Programming Urban-Area Applications by Exploiting Public Transportation

The evolution of smartphones has given rise to urban-area applications: applications that communicate in a city by means of the public (moving) infrastructure (e.g., buses and trams). In this setting, applications need to communicate with and discover each other using intermediaries that move around the city and transfer data between them. This requires programmers to scatter code that deals with routing messages to the correct place and deal with network failures all over their programs. Our approach allows the programmer to specify urban-area applications in a high-level manner without the burden of directly encoding communication using intermediaries. We present this as a translation from a high-level object-oriented programming paradigm to a low-level communication mechanism. This translation allows the programmer to restrict routing of messages to, for example, a certain number of hops, geographic areas, or even types of carrier devices. In addition, we show how high-level group messaging can be efficiently represented in the low-level communication. Finally, we document our experiences in setting up a small-scale real-world urban-area application.

Programming urban-area applications

The evolution of smartphones has given rise to urban-area applications: applications that communicate in a city by means of the public (moving) infrastructure, e.g. buses and trams. In this setting, applications need to communicate and discover each other using intermediaries that move around the city and transfer data between them. This requires programmers to scatter code that deals with routing messages to the correct place and dealing with network failures all over their programs. Our approach allows the programmer to specify urban-area applications in a high-level manner without the burden of directly encoding communication using intermediaries. We present this as a translation from a high-level object-oriented programming paradigm to a low-level communication mechanism.

Network-aware references for pervasive social applications

In recent years, mobile devices such as smartphones have become more powerful, gaining the ability to communicate using multiple networking technologies. This evolution has given rise to pervasive social applications that enable social networking on the move. Currently, it is hard to take advantage of the available networking technologies because communication has to be managed separately for each technology. This forces programmers to manually keep track of the connectivity state and duplicate communication code per connection. This paper presents network-aware references, a distributed object-oriented programming abstraction that combines multi-networking and network awareness. They abstract over the implementation details of the different networking technologies while allowing programmers to react to changes in the connectivity of different networks around them.

Coordination Models and Languages

This book constitutes the refereed proceedings of the 13th International Conference on Coordination Models and Languages, COORDINATION 2011, held in Reykjavik, Iceland, in June 2011, as one of the DisCoTec 2011 events. The 14 revised full papers presented were carefully reviewed and selected from 35 submissions. The conference focuses on the design and implementation of models that allow compositional construction of large-scale concurrent and distributed systems, including both practical and foundational models, run-time systems, and related verication and analysis techniques

Objects in Space

The paper presents a research agenda that we are currently executing for programming mobile applications that write and read information to and from passive RFID tags. Modern tags can host up to several kilobytes of information which makes it possible to store real software objects (in the object-oriented sense) that can even refer to each other. This gives the term ‘spatial database’ an entirely new meaning. The paper motivates the need for new programming language constructs that are specifically targeted towards representing objects on tags, designating specific tags in the application’s proximity and keeping the internal status of the mobile application causally connected to its physical surrounding.