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research:context [2006/06/30 13:55]
jorge
research:context [2009/11/30 16:55] (current)
dharnie *prog->soft
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-===== Role-Based Ambient Communications =====+===== Context-Dependent Behaviour Adaptations ===== 
 +[[http://soft.vub.ac.be/~jvallejo/|Jorge Vallejos]]
  
-{{ ambientrefs.jpg }}+==== Motivation ====
  
-As said in the presentation of this research group, we are working on pervasive computing: In the futurepeople will be surrounded by mobile and embedded devices all the time. 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 timeExamples include geographical locationtime of day, temperature, other users in the environment, their respective context information, and so on. Finally, 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.+Within the domain of pervasive computing, context-awareness has commonly been defined as the ability of an application to adapt itself to its dynamic environment. The context of an application is defined as any information or service in the application's surroundings that may influence its current state or behaviourIn this researchwe focus on the influence of such context on the communications between the entities of a software system.
  
 +Our observation is that in an interaction between two entities, the behaviour of the message receiver may not only depend on its own context, but also on the context of the sender. We have illustrated this idea in a high level **[[research:context-aware_cell_phone|context-aware cell phone scenario]]**.
  
-[[research:terms:monets|mobile networks]]. [[research:terms:monets|elsewhere]].+We claim that in order to deal with context-dependent communications in mobile networks, we need a model that satisfies the following conditions:
  
-== Motivation ==+  * **Dynamic Context Adaptation**: Context information may influence the behaviour of a device. Applications should adapt to their context by dynamically switching of behaviour.
  
-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 number of desirable properties of remote references for mobile networks which current remote referencing abstractions do not offer:+  * **Dynamic Behaviour Composition**: The resulting behaviour is typically composition of possible different behaviours. Applications should be based on composable parts representing partial context-dependent adaptations.
  
-  **Dynamic Context Adaptation**: Context information may influence the behaviour of device. Context-aware applications should adapt to their context by dynamically switching of behaviour.+  * **Context Passing Mechanism**: It is not only the context of one device that determines its behavior, but also the context of other devices potentially play an important roleIn the case of context-dependent communications, the context information of the message sender should also be taken into account to decide the behaviour adaptation of the receiver. We require therefore a way to get acknowledgment of the sender’s context information.
  
-  - **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.+==== Design ====
  
-  - **Context Passing Mechanism**It is not only the context of one device that determines its behaviourbut also the context of other devices potentially play an important role.+At our [[http://soft.vub.ac.be|lab]], we are currently exploring different language constructs for the development of context-aware applications. Here we present one of thes constructs called Split Objects (Bardou et alECOOP 1996). In such a model, application entities are composed of roles (known as viewpoints) which represent the different behaviours the entity can adopt. A role is a particular point of view on an entity that has an identification and a partial definition of that entity. The model's message sending protocol allows the specification of the role the receiver should adopt to respond to the message. Hence, if context-dependent behaviour is modelled as roles, an application could adapt to its context by just assuming the appropriate role.
  
-== Design ==+{{ rolemodel02.jpg?455x318| Click the image to enlarge }}
  
-Ambient references unify two concepts: they are both a peer-to-peer discovery channel //and// an asynchronous communication channel to a remote object.+The problem with the split objects model is that the message sender must know before hand which are the roles a receiver could take. In dynamic environments like mobile open networks, this acknowledgment is practically impossible and undesirable (due to the heterogeneity and autonomicity of the participants). Hence we have extended this model in such a way that the sender only have to include its own context information in the messages (and not a role). At the receiver side there will be a reasoning engine that will take as input the context of both sender and receiver, and will map this information to role. We have called this entity the context-dependent role selector. For further information about this solution, we refer the interested reader to [ [[http://soft.vub.ac.be/Publications/2006/vub-prog-tr-06-17.pdf|this paper]] ].
  
-== Ongoing and Future Work ==+==== Ongoing and Future Work ====
  
-- Composition of context-dependent application behaviours using prototype-based solutions (delegation hierarchies, split objects, subjective objects etc.). +These are the different research topics we have identified so far:
-- 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 ==+  * 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.
  
-A detailed explanation of ambient references can be found in [[ftp://prog.vub.ac.be/tech_report/2006/vub-prog-tr-06-07.pdf|this technical report]].+  * Rule-based systems for context reasoning and role selection.
  
-== Further Reading ==+  * Combining actor and role models for the development of context-dependent applications.
  
-Ambient References: Addressing Objects in Mobile NetworksTom Van CutsemJessie DedeckerStijn MostinckxElisa Gonzalez BoixTheo D'HondtWolfgang De MeuterIn //Technical Report VUB-PROG-TR-06-10, Vrije Universiteit Brussel//, 2006 [ [[http://prog.vub.ac.be/Publications/2006/vub-prog-tr-06-10.pdf|download]] ]+  * Ad-hoc and intentional actor grouping. 
 + 
 +  * Intra and Inter actor layers for context-dependent adaptations. 
 + 
 +  * Dynamic scope for context-dependent communications. 
 + 
 +==== Further Reading ==== 
 + 
 +**A Role-Based Implementation of Context-Dependent Communications Using Split Objects**Jorge VallejosPeter EbraertBrecht Desmet. In "Proceedings of the workshop on Revival of Dynamic Languagescollocated with ECOOP 2006NantesFrance". [ [[http://soft.vub.ac.be/Publications/2006/vub-prog-tr-06-17.pdf|download]] ]
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