## Bigraphical Models of Context-aware Systems (2005)

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Citations: | 28 - 14 self |

### BibTeX

@TECHREPORT{Birkedal05bigraphicalmodels,

author = {L. Birkedal and S. Debois and E. Elsborg and T. Hildebrandt and H. Niss},

title = {Bigraphical Models of Context-aware Systems},

institution = {},

year = {2005}

}

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### Abstract

As part of ongoing work on evaluating Milner’s bigraphical reactive systems, we investigate bigraphical models of context-aware systems, a facet of ubiquitous computing. We find that naively encoding such systems in bigraphs is somewhat awkward; and we propose a more sophisticated modeling technique, introducing Plato-graphical models, alleviating this awkwardness. We argue that such models are useful for simulation and point out that for reasoning about such bigraphical models, the bisimilarity inherent to bigraphical reactive systems is not enough in itself; an equivalence between the bigraphical reactive systems themselves is also needed.

### Citations

775 | R.: Context-aware computing applications
- Schilit, Adams, et al.
- 1994
(Show Context)
Citation Context ...t aim. We investigate modeling of context-aware systems, a vital aspect of ubiquitous systems. A context-aware application is an application that adapts its behaviour depending on the context at hand =-=[26]-=-, interpreting “context” to mean the situation in which the computation takes place [10]. The canonical example of such a situation is the location of the device performing the computation; systems se... |

704 | Towards a Better Understanding of Context and ContextAwareness
- Dey, Abowd
- 2000
(Show Context)
Citation Context ...stems. A context-aware application is an application that adapts its behaviour depending on the context at hand [26], interpreting “context” to mean the situation in which the computation takes place =-=[10]-=-. The canonical example of such a situation is the location of the device performing the computation; systems sensitive to location are called location-aware. As an example, a location-aware printing... |

260 | Pict: a programming language based on the picalculus - Pierce, Turner - 2000 |

237 | There is more to context than location
- Schmidt, Beigl, et al.
- 1999
(Show Context)
Citation Context ...-aware printing2 L. Birkedal, S. Debois, E. Elsborg, T. Hildebrandt, and H. Niss system could send a user’s print job to a printer close by. (For notions of context different from location, refer to =-=[27]-=-; for large-scale practical examples, see [1].) To observe changes in the context, context-aware systems typically include a separate context sensing component that maintains a model of the current co... |

182 | Implementing a sentient computing system
- Addlesee, Curwen, et al.
(Show Context)
Citation Context ...lsborg, T. Hildebrandt, and H. Niss system could send a user’s print job to a printer close by. (For notions of context different from location, refer to [27]; for large-scale practical examples, see =-=[1]-=-.) To observe changes in the context, context-aware systems typically include a separate context sensing component that maintains a model of the current context. Such models are known as context model... |

148 |
Concurrent Programming in ML
- Reppy
- 1999
(Show Context)
Citation Context ...ebois, E. Elsborg, T. Hildebrandt, and H. Niss To implement the proxy, encode as a BRS a programming language L with data structures, communication primitives, and concurrency, e.g., Pict [22] or CML =-=[24]-=-. (We return to this assumption below.) That is, define a translation from terms of L to bigraphs, and add reaction rules encoding the operational semantics of L. Then implement the location model, th... |

140 | Modelling Context Information in Pervasive Computing Systems
- Henricksen, Indulska, et al.
- 2002
(Show Context)
Citation Context ... To observe changes in the context, context-aware systems typically include a separate context sensing component that maintains a model of the current context. Such models are known as context models =-=[12]-=- or, more specifically, location models [2]. The above-mentioned location-aware printing system would need to maintain a model of the context that supports finding the printer closest to a given devic... |

120 | Deriving bisimulation congruences for reactive systems
- Leifer, Milner
- 2000
(Show Context)
Citation Context ..., S. Debois, E. Elsborg, T. Hildebrandt, and H. Niss suggests that equivalence of BRSs is a key notion currently missing. One possible direction would be to try recover from the notion of WRS-functor =-=[16]-=- — functors that preserve reaction rules — a notion of a BRS implementing another BRS. 7 Conclusion & Future Work We have initiated an evaluation of the use of bigraphical reactive systems for models ... |

101 |
Hot Topics: Ubiquitous Computing
- Weiser
- 1993
(Show Context)
Citation Context ...ed transition system, the behavioural equivalence (bisimilarity) of which is a congruence. There are two principal aims for the theory of bigraphical reactive systems: (1) to model ubiquitous systems =-=[28]-=-, capturing mobile locality in the place graph and mobile connectivity in the link graph; and (2) to be a meta-theory encompassing existing calculi for concurrency and mobility. To date, the theory ha... |

62 | Bigraphs and mobile processes (revised
- Jensen, Milner
- 2004
(Show Context)
Citation Context ...lso needed. 1 Introduction The theory of bigraphical reactive systems, due to Milner and co-workers, is based on a graphical model of mobile computation that emphasizes both locality and connectivity =-=[15, 19, 21]-=-. A bigraph comprises a place graph, representing locations of computational nodes, and a link graph, representing interconnection of these nodes. We give dynamics to bigraphs by defining reaction rul... |

57 |
Bigraphs and transitions
- Jensen, Milner
- 2003
(Show Context)
Citation Context ...ta-theory encompassing existing calculi for concurrency and mobility. To date, the theory has been evaluated only wrt. the second aim: We have bigraphical understanding of Petri nets [18], π-calculus =-=[13, 15, 14]-=-, CCS [21], mobile ambients [13], HOMER [5], and λ-calculus [19, 20]. The present paper initiates the evaluation of the first aim. We investigate modeling of context-aware systems, a vital aspect of u... |

51 | Pure bigraphs: Structure and dynamics
- Milner
(Show Context)
Citation Context ...lso needed. 1 Introduction The theory of bigraphical reactive systems, due to Milner and co-workers, is based on a graphical model of mobile computation that emphasizes both locality and connectivity =-=[15, 19, 21]-=-. A bigraph comprises a place graph, representing locations of computational nodes, and a link graph, representing interconnection of these nodes. We give dynamics to bigraphs by defining reaction rul... |

45 |
On location models for ubiquitous computing
- Becker, Durr
(Show Context)
Citation Context ...aware systems typically include a separate context sensing component that maintains a model of the current context. Such models are known as context models [12] or, more specifically, location models =-=[2]-=-. The above-mentioned location-aware printing system would need to maintain a model of the context that supports finding the printer closest to a given device. Such models are informal. There are only... |

37 | Axioms for bigraphical structure
- Milner
- 2004
(Show Context)
Citation Context ...rly, B : 〈2, {z}〉 → 〈2, ∅〉 and C : 〈0, ∅〉 → 〈2, {z}〉. The graphical representation used above is handy for modeling, but unwieldy for reasoning. Fortunately, bigraphs have an associated term language =-=[7, 17]-=-, which we use (albeit in a sugared form) in what follows. The language is summarized in Table 1. Here are, in order of increasing complexity, term representations of the bigraphs A, B and C. C = secr... |

33 | Bigraphs for Petri Nets
- Milner
- 2004
(Show Context)
Citation Context ...nd (2) to be a meta-theory encompassing existing calculi for concurrency and mobility. To date, the theory has been evaluated only wrt. the second aim: We have bigraphical understanding of Petri nets =-=[18]-=-, π-calculus [13, 15, 14], CCS [21], mobile ambients [13], HOMER [5], and λ-calculus [19, 20]. The present paper initiates the evaluation of the first aim. We investigate modeling of context-aware sys... |

33 | Pure bigraphs - Milner - 2005 |

21 | Spatial logics for bigraphs, in
- Conforti, Macedonio, et al.
- 2005
(Show Context)
Citation Context ... on this in Section 6. We imagine that adding more flexibility to the reaction rules might make it easier to program directly with bigraphs. One possible attempt is to use spatial logics for bigraphs =-=[6]-=- in combination with sorting, to get control of the contexts in which a particular reaction rule applies. In the following sections, we propose another way to model context-aware systems in bigraphs, ... |

18 | Bigraphical Semantics of Higher-Order Mobile Embedded Resources with Local Names
- Bundgaard, Hildebrandt
(Show Context)
Citation Context ... P , where the table prts x(raw) and the physical printer prt x(raw | dat) are linked. The dynamics of P state that if there is a job and a known, idle PCLprinter, the proxy may activate this printer =-=(5)-=-; that if there is a job, no known PCL-printer, and an idle raw-printer, the context may activate that printer (6); and finally, that the proxy may discover a previously unknown printer (7, 8). The dy... |

18 | A formal treatment of context-awareness
- Roman, Julien, et al.
- 2004
(Show Context)
Citation Context ...s finding the printer closest to a given device. Such models are informal. There are only very few formal models of context-aware computing (refer to [11] for an overview). We point out Context Unity =-=[25]-=-; in spirit, our proposal is somewhat closer to process calculi than Context Unity is. However, bigraphs differ from traditional process calculi in that we get to write our own reaction rules. In over... |

15 |
Bigraphs whose names have multiple locality
- Milner
- 2004
(Show Context)
Citation Context ...lso needed. 1 Introduction The theory of bigraphical reactive systems, due to Milner and co-workers, is based on a graphical model of mobile computation that emphasizes both locality and connectivity =-=[15, 19, 21]-=-. A bigraph comprises a place graph, representing locations of computational nodes, and a link graph, representing interconnection of these nodes. We give dynamics to bigraphs by defining reaction rul... |

14 | Basic observables for a calculus for global computing
- Nicola, Gorla, et al.
- 2004
(Show Context)
Citation Context ...orld. 4 Plato-graphical Models of Context-aware Systems The naive model of the previous section shares an important characteristic with recent proposals of formal models for context-aware computation =-=[4, 8, 25]-=- that comprise agents and contexts only: These models take the agent’s ability to determine what is the present context as given. We contend that for some systems, it is natural to model not only the ... |

13 | Jadwiga Indulska, and Andry Rakotonirainy. Modelling Context Information in Pervasive computing systems - Henricksen |

12 | On calculi for contextaware coordination
- Braione, Picco
- 2004
(Show Context)
Citation Context ...e(pc x | pda y(secret) | pda y) (We omit details on what it means to match connections; refer to one of [15, 21].) It is occasionally convenient to limit the contexts in which a reaction rule applies =-=[4]-=-, i.e., we might want to limit the above example reaction rule to apply only in the left wing of the building. To this end, bigraphs can be equippedBigraphical Models of Context-aware Systems 5 with ... |

7 |
Axiomatization of Binding Bigraphs (Revised
- Damgaard, Birkedal
- 2005
(Show Context)
Citation Context ...rly, B : 〈2, {z}〉 → 〈2, ∅〉 and C : 〈0, ∅〉 → 〈2, {z}〉. The graphical representation used above is handy for modeling, but unwieldy for reasoning. Fortunately, bigraphs have an associated term language =-=[7, 17]-=-, which we use (albeit in a sugared form) in what follows. The language is summarized in Table 1. Here are, in order of increasing complexity, term representations of the bigraphs A, B and C. C = secr... |

4 | Bigraphs by Example
- Debois, Damgaard
- 2005
(Show Context)
Citation Context ...a query such as “find nearest neighbor”, which conceptually is only slightly harder, is significantly harder to implement. (Other examples plagued by essentially the same difficulties can be found in =-=[9]-=-.) Consider the following bigraph representing devices (e.g., PDAs) located at locations (e.g., offices, meeting rooms) within a building. l = /w./x./y./z.loc (loc (loc (loc (devw) | loc (devx | devy)... |

3 |
The republic, book vii, 360 B.C. Translation by Benjamin Jowett
- Plato
- 2000
(Show Context)
Citation Context ...e propose a model of context-aware computing that comprises three bigraphical reactive systems: the context C; its representation or proxy P; and the computational agents A. Drawing on classical work =-=[23]-=-, specifically The Allegory of the Cave, we call such a model Plato-graphical. Definition 3 (Plato-graphical model). A Plato-graphical model is a triple (C, P, A) of bigraphical reactive systems, such... |

1 |
Context-awareness: Models and analysis. Talk at 2nd UK-UbiNet Workshop, slides atwww.cogs.susx.ac.uk/users/matthewh/talks.html
- Hennessy
- 2004
(Show Context)
Citation Context ...ed to maintain a model of the context that supports finding the printer closest to a given device. Such models are informal. There are only very few formal models of context-aware computing (refer to =-=[11]-=- for an overview). We point out Context Unity [25]; in spirit, our proposal is somewhat closer to process calculi than Context Unity is. However, bigraphs differ from traditional process calculi in th... |

1 |
Bigraphs: A tutorial. Slides
- Milner
- 2005
(Show Context)
Citation Context ... date, the theory has been evaluated only wrt. the second aim: We have bigraphical understanding of Petri nets [18], π-calculus [13, 15, 14], CCS [21], mobile ambients [13], HOMER [5], and λ-calculus =-=[19, 20]-=-. The present paper initiates the evaluation of the first aim. We investigate modeling of context-aware systems, a vital aspect of ubiquitous systems. A context-aware application is an application tha... |

1 |
Pict: A prog. lang. based on the pi-calculus
- Pierce, Turner
- 2000
(Show Context)
Citation Context ...rkedal, S. Debois, E. Elsborg, T. Hildebrandt, and H. Niss To implement the proxy, encode as a BRS a programming language L with data structures, communication primitives, and concurrency, e.g., Pict =-=[22]-=- or CML [24]. (We return to this assumption below.) That is, define a translation from terms of L to bigraphs, and add reaction rules encoding the operational semantics of L. Then implement the locati... |

1 | Debois and Troels C. Damgaard. Bigraphs by Example - Søren - 2005 |

1 | Høgh Jensen. Mobile Processes in Bigraphs - Ole - 2005 |