Context-Oriented Behavioral Programming

Theoretical Computer Science, 2007

Context-aware computing refers to a paradigm in which applications sense aspects of the environment and use this information to adjust their behavior in response to changing circumstances. In this paper, we present a formal model and notation (Context UNITY) for expressing quintessential aspects of context-aware computations; existential quantification, for instance, proves to be highly effective in capturing the notion of discovery in open systems. Furthermore, Context UNITY treats context in a manner that is relative to the specific needs of an individual application and promotes an approach to context maintenance that is transparent to the application. In this paper, we construct the model from first principles, introduce its proof logic, and demonstrate how the model can be used as an effective abstraction tool for context-aware applications and middleware.

Computer Languages, Systems & Structures, 2012

In mobile computing scenarios, users move in different environments and applications can automatically explore their surroundings. This type of context-aware application is an emerging trend, so far not widely disseminated. We believe that the proposal of a programming model specifically designed for the specification of context-aware applications, using general abstractions, will foster a rapidly widespread of such kind of software. In this article, we propose the use of the Holoparadigm (in short Holo) to fill this gap. We created a programming language based on Holo (called HoloL) to demonstrate the strengths of Holoparadigm to develop context-aware applications. The article uses a sample scenario to show the Holo's practical aspects related to implementation of context-aware applications. We also present a platform to HoloL (called HoloEnv), composed of a compiler, a virtual machine, and a distributed execution environment. Finally, different performance aspects of the HoloEnv's components were evaluated through experimental results.

Proceedings of the 12th annual international conference on Aspect-oriented software development - AOSD '13, 2013

Context-oriented programming emerged as a new paradigm to support fine-grained dynamic adaptation of software behaviour according to the context of execution. Though existing context-oriented approaches permit the adaptation of individual methods, in practice behavioural adaptations to specific contexts often require the modification of groups of interrelated methods. Furthermore, existing approaches impose a composition semantics that cannot be adjusted on a domain-specific basis. The mechanism of traits seems to provide a more appropriate level of granularity for defining adaptations, and brings along a flexible composition mechanism that can be exploited in a dynamic setting. This paper explores how to achieve context-oriented programming by using traits as units of adaptation, and trait composition as a mechanism to introduce behavioural adaptations at run time. First-class contexts reify relevant aspects of the environment in which the application executes, and they directly influence the trait composition of the objects that make up the application. To resolve conflicts arising from dynamic composition of behavioural adaptations, programmers can explicitly encode composition policies. With all this, the notion of context traits offers a promising approach to implementing dynamically adaptable systems. To validate the context traits model we implemented a JavaScript library and conducted case studies on context-driven adaptability.

2011

Abstract Context-aware mobile applications can benefit from context inference adaptation based on run-time operating conditions, such as battery life or sensor availability. Developing applications with such adaptable behavior, however, is notoriously cumbersome, as developers need to deal with low-level system interfacing and programming issues.

2018

As devices, platforms, and technologies for IoT (Internet-of-Things) and robots, develop, the question of how to best specify the behavior of such systems so that it is both robust and manageable becomes central. Current practices may suffice when working with simple requirements. However, behavior specification given in current languages often become unwieldy as they grow to accommodate complex conditions, exceptions, and priorities. To address this, we propose to use the scenariobased programming approach, and specifically, the graphical language of live sequence charts (LSC). This addresses one aspect of the specification growth issue by allowing a natural breakdown of the specification in alignment with the requirements. The other aspect of our solution, aiming at further simplifying and shortening the specification, is based on subjecting these scenarios to context-a key concept in IoT and autonomous robot modeling. Specifically, we propose additions to LSC for subjecting behavioral scenario charts to contexts and a methodology to work with these idioms.

2013 IEEE 14th International Symposium on "A World of Wireless, Mobile and Multimedia Networks" (WoWMoM), 2013

Several frameworks have already been proposed to simplify the development of context-aware applications. These frameworks are focused on collecting and publishing contextual data, and on providing common semantics, definitions and representations of these data. This implies that applications share the same semantics, which limits the range of use cases where a framework can be used since that assumption induces a strong coupling between context management and application logic. This article proposes a framework that decouples context management from application business logic. The aim is to reduce the overhead for applications that run on resource-limited devices while still providing efficient mechanisms to support context-awareness and behavior adaptation. This framework implements an innovative approach that involves third parties in the process of context processing definition by structuring it in atomic functions, and describing it with an XML-based programming language. Its implementation and evaluation demonstrates the benefits, in terms of flexibility, of using trusted design patterns from software engineering for developing context-aware application.

Information and Software Technology, 2015

Context: Context-oriented programming languages provide dedicated programming abstractions to define behavioral adaptations and means to combine those adaptations dynamically according to sensed context changes. Some of these languages feature programming abstractions to explicitly define interaction dependencies among contexts. However, the semantics of context activation and the meaning of dependency relations have been described only informally, which in some cases has led to incorrect specifications, faulty implementations and inconsistent system behavior. Objective: With the aim of avoiding faulty implementations and inconsistencies during system execution, this paper proposes both a formal and run-time model of contexts, context activation and context interaction. Method: As a formal and computational basis, we introduce context Petri nets, a model based on Petri nets, which we found to match closely the structure of contexts in context-oriented systems. The operational semantics of Petri nets permits the modeling of run-time context activations. Existing Petri net analyses allow us to reason about system properties. As validation, we carried out small and medium-sized case studies. Results: In the cases explored, context Petri nets served effectively as underlying run-time model to ensure that declared context interaction constraints remain consistent during context manipulation. Moreover, context Petri nets enabled us to analyze certain properties regarding the activation state of particular contexts. Conclusion: Context Petri nets thus proved to be appropriate to encode and manage the semantics of context activation, both formally and computationally, so as to preserve the consistency of contextoriented systems.

Modern software systems are increasingly complex and are controlling critical activities in many different domains. The traditional assumption that these systems will work in a controlled context is slightly vanishing. Therefore, it emerges the need of methodologies able to determine under what conditions desired goals will be achieved and behavioural strategies will be preserved despite (often unavoidable) adaptations. In this paper we use the cognitive psychology concept of schema to identify the set of properties that an adaptable system has to maintain when adapting to changed context. The methodology we propose, called AC-contract (Adaptable Code-contract), starts from high-level requirements and identifies properties that should hold locally on single parts of the system. Local properties are represented as contracts directly on the programming language. Specifically, AC-contract is able to embed logical propositions in the source code as annotations; moreover, it enables veri...

2007

Abstract The context modelling language (CML), derived from object role modeling (ORM), is a powerful approach for capturing the pertinent object types and relationships between those types in context-aware applications. Its support for data quality metrics, context histories and fact type classifications make it an ideal design tool for context-aware systems. However, CML currently lacks a suitable representation for exchanging context models and instances in distributed systems.