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Role-Based Ambient Communications

Motivation

As said in the presentation of this website, we are working on the field of pervasive computing. In such a setting, context will play an important role. The context consists of all the information and services that are reachable by user devices at each given point in time. Examples include geographical location, time of day, temperature, other users in the environment, their respective context information, and so on. The software that runs on user devices is influenced by such context information, and the software should ultimately display different behavior according to the context of use.

rolescenario01.jpg

The figure above illustrates such a context influence in a high-level scenario: Assume you are attending a meeting and someone wants to reach you via his cell phone. However, since this is an important meeting, you may not want to be disturbed by such incoming calls. Therefore, the cell phone should provide a way to react to the context of use: You are currently in an important meeting - so phone calls should be signaled in a discreet way only. Assume further that an important relative of yours is currently in the hospital, and you want to be sure that you don’t miss any call from the hospital. In this case, you want to receive a loud signal, even though you are in an important meeting. What is important in this setting is the following: There are different context parameters that should influence the behavior of your device. Different context parameters may lead to different results in how the resulting behavior should look like. Finally, and this is a key issue, it is not only important what the context of your device looks like, but also what the context of the calling device is. Here, you may not know what the phone number or even the identity of the person is who will call you from the hospital. The only information you can rely on is the context of the calling device, which is the fact that the call originates from the hospital. In fact, you indeed want any call from the hospital to get through. So the resulting behavior on your device is potentially influenced by the contexts of one more device at least.

So here is a summary of the issues we have discussed so far:

  1. Dynamic Context Adaptation: Context information may influence the behaviour of a device - it should signal incoming calls in different ways, give you services that are of importance to you in your current environment, and so on. Context-aware applications should adapt to their context by dynamically switching of behaviour.
  1. Dynamic Behaviour Composition: The resulting behaviour is a composition of possible different behaviours - you don’t want the phone’s behavior to change completely, but only different variations of the same behavior. Context-aware applications should be based on composable parts representing partial context-dependent adaptations.
  1. Context Passing Mechanism: It is not only the context of one device that determines its behaviour, but also the context of other devices potentially play an important role.

mobile networks. elsewhere.

Motivation

One may wonder why new referencing abstractions are required for mobile networks. In order to motivate the need for new referencing abstractions at the language level, we list a number of desirable properties of remote references for mobile networks which current remote referencing abstractions do not offer:

  1. Dynamic Context Adaptation: Context information may influence the behaviour of a device. Context-aware applications should adapt to their context by dynamically switching of behaviour.
  1. Dynamic Behaviour Composition: The resulting behaviour is a composition of possible different behaviours.Context-aware applications should be based on composable parts representing partial adaptations of behaviour.
  1. Context Passing Mechanism: It is not only the context of one device that determines its behaviour, but also the context of other devices potentially play an important role.
Design

Ambient references unify two concepts: they are both a peer-to-peer discovery channel and an asynchronous communication channel to a remote object.

Ongoing and Future Work

- Composition of context-dependent application behaviours using prototype-based solutions (delegation hierarchies, split objects, subjective objects etc.). - Context-dependent adaptations of behaviour using role-based models. - Rule-based systems for context reasoning and role selection. - Role-based communications. - Combining actor and role models for the development of context-dependent applications. - Ad-hoc and intentional actor grouping. - Intra and Inter actor layers for context-dependent adaptations. - Dynamic scope for context-dependent communications.

Implementation

A detailed explanation of ambient references can be found in this technical report.

Further Reading

Ambient References: Addressing Objects in Mobile Networks. Tom Van Cutsem, Jessie Dedecker, Stijn Mostinckx, Elisa Gonzalez Boix, Theo D'Hondt, Wolfgang De Meuter. In Technical Report VUB-PROG-TR-06-10, Vrije Universiteit Brussel, 2006 [ download ]

research/context.1151672295.txt.gz · Last modified: 2006/06/30 15:53 (external edit)