Ricardo Couto Antunes da Rocha

Evolutionary and efficient context management in heterogeneous environments

Mobile computing and pervasive environments are mainly characterized by heterogeneity of devices, with different capabilities, resources, operating systems and applications. In a realistic scenario for context-aware computing, middleware should be deployable in the whole distributed system, despite devices resource limitations, and the developer should be able to evolve the context model when new context-aware applications or context providers are introduced. This paper discusses how context modeling and design of middleware architecture can impact on the efficiency of provision, distribution and access of context information in heterogeneous environments. This paper describes a middleware architecture and design strategies in order to address such requirements.

Middleware for ubiquitous context-awareness

This position paper discusses the challenges and trade-offs of implementing a middleware that supports ubiquitous contextawareness, i.e., a scenario where context-aware applications may move throught network environments without suffering disruptions in their context-based interactions. We present a middleware approach based on the concept of context domains that satisfy some of the requirements of this scenario.

A Middleware Architecture for Context-Aware and Location-Based Mobile Applications

The development of location and context-aware applications is greatly facilitated by the use of context-provisioning middleware. However, development of such applications still remains a challenge from the point of view of software engineering. In this paper we present MoCA, a service-oriented middleware architecture that supports the development and deployment of distributed context-aware applications for mobile users. Besides explaining its main services and APIs, we discuss in which ways the MoCA architecture supports some well-known software engineering principles that apply to the design and implementation of context-aware applications. Furthermore, we give an overview of its usage and present the most notable prototype applications that have been developed on the top of MoCA.

Domain-based context management for dynamic and evolutionary environments

Research in context-aware computing has produced a number of application prototypes, frameworks, middlewares and models for describing context. However, development of ubiquitous context-aware applications is still a difficult task because current middleware systems are focused on isolated and static context-aware environments. Currently, applications require a global knowledge of the context-aware infrastructures in order to establish context-based interactions, and they suffer of problems such as disruptions when a context-aware environment evolves. The goal of this thesis is to develop a distributed middleware for context-aware computing that allows applications to maintain context-based continuous interactions, even in a highly dynamic environment. In order to achieve this goal, we propose a context management strategy based on context domains. We argue that this approach supports four important requirements for context-aware ubiquitous applications: distributed management of context, support for seamless evolution of context-aware systems, dynamic context discovery and domains of context perception.

Context Management for Distributed and Dynamic Context-Aware Computing

Research in context-aware computing has produced a number of middleware systems for context management. However, development of ubiquitous context-aware applications is still a challenge because most current middleware systems are still focused on isolated and static context-aware environments. Context-aware environments are inherently dynamic as a result of occasional additions or upgrade of sensors, applications or context inference mechanisms. Context Management for Distributed and Dynamic Context-Aware Computing proposes a novel architecture for context management based on the concept of context domains, allowing applications to keep context interests across distributed context management systems. The authors describe a distributed middleware that implements the aforementioned concepts, without compromising scalability and efficiency of context access.

Flexible simulation of distributed protocols for mobile computing

<italic>This article describes</italic> MOBI<italic>CS (Mobile Computing Simulator), a distributed protocol simulator for mobile computing that facilitates the prototyping and testing of protocols based on high-level programming abstractions and simulation transparency. The main contribution of</italic> MOBI<italic>CS is the implementation of a software architecture for simulators that supports interchangeable simulation modes without affecting the distributed protocols being prototyped. Through</italic> MOBI<italic>CS we aim at providing a unified tool both for testing the correctness of a protocol and for evaluating its performance in a simulated environment.</italic>

Domain-Based Context Management

The support for context interests of variable wideness introduces several challenges for context management. First of all, consumers demand contextual interoperability, in order to enable the interpretation of a context interest across various context management systems. In order to support expressions of closed and open domain, a middleware must support address resolution of context management systems and enable the definition of context scope boundaries and their management. Context management based on context domains is an approach for supporting interests of variable wideness in distributed and dynamic environments.

Implementation and Evaluation

The feasibility of the context domains approach for context management is demonstrated through an implementation of a distributed middleware. Test results have shown that the implementation’s performance is appropriate to the target scenario. The event engine of the middleware is based on a distributed event-based system called Naradabrokering. In particular, the middleware adopts Naradabrokering’s XML engine. Context information is represented as XML events, which the engine matches with context interests described in XPath expressions. This middleware allows the development of context-aware applications for mobile devices, and runs in two platforms: Android and Java J2ME CDC 1.1.

Middleware for Context Management Based on Context Domains

Context management based on context domains is an approach for supporting interests of variable wideness in distributed and dynamic environments. Context domains establish distributed boundaries for both context modeling and management. The design of a distributed middleware based on this concept should address an architecture that enables efficient context-based interaction in both localized and distributed pairs of consumer–provider, protocols for discovering context management systems, and a suitable programming model for context-aware applications. In addition, the middleware should address some additional requirements, such as its usage in resource-constrained portable devices.

Foundations of Context Management in Distributed and Dynamic Environments

Context information is data that describes the state of a certain entity at a specific moment. A context management system is a computational element responsible for binding context providers, which produce context information, and context consumers, typically represented by context-aware applications. The main task of a context management system is to match consumer’s interests with probed context information. The complexity of context management in a distributed scenario is defined by the wideness of an interest, i.e. the number of context management systems that should be involved in an interest matching. If a distributed scenario is also open, heterogeneous and dynamic, than the wideness of an interest is variable, as a result of characteristics such as dynamic introduction of new sensors and evolution of context models. The support of context interest of variable wideness imposes challenging requirements for context management systems.