Zigor Salvador

Managing Intelligent Services for People with Disabilities and Elderly People

Ambient Supported Living systems for people with physical, sensory or cognitive restrictions have to guarantee that the environment is safe, fault tolerant and universally accessible. In addition it is necessary to overcome technological challenges, common to ubiquitous computing, such as the design of a middleware layer that ensures the interoperability of multiple wired and wireless networks and performs discovery actions. On top of that the system has to provide efficient support to the intelligent applications designed to assist people living there. In this paper we present the AmbienNet architecture designed to allow structured context information to be shared among the intelligent applications that support people with disabilities or elderly people living alone.

Architectures for ubiquitous environments

Ubiquitous (or pervasive) systems are characterized by component distribution and dynamic behavior. In a ubiquitous environment, such as a future automated home (also called a domotic environment), user devices explore the environment to discover resources and services to control. This paper analyzes architectures for ubiquitous systems based on the structure of the environment and the way discovery mechanisms (such as Jini and UPnP) operate. As a result, a framework to classify the architectures is provided. As an example, a UPnP-based prototype for a domotic environment is presented. We use standard devices, such as PDAs and cell phones, to allow users to access and control virtual resources. The system provides user management capabilities, persistence, and standard interfaces, while preserving full UPnP compatibility. The prototype can be easily transferred to future realistic domotic installations.

An architecture for the personalized control of domotic resources

This work presents an architecture for the management and personalized control of devices in a <i>domotic</i> environment (i.e., an automated home). The architecture allows for user and profile management from mobile hand-held devices such as PDAs and cell phones. The system provides for interaction from any device fitted with TCP/IP support and a web browser, so that the specific characteristics of the access device are not a conditioning factor. We have implemented a prototype to test out the application of the architecture in domotic environments. We have used virtual UPnP devices that emulate domotic devices on PCs, a local area network interconnecting the PCs to form a domotic network, and a PDA with Bluetooth and a cell phone with GPRS connection as wireless access devices. A key design goal was that the prototype could be easily transferred to future domotic installations with real devices, possibly interconnected by the home power line.

Phoenix: A Protocol for Seamless Client Mobility in Publish/Subscribe

This paper presents Phoenix, a routing protocol for content-based publish/subscribe systems that supports seamless client mobility. Our protocol is based on the Simple Routing approach and requires brokers to maintain a global vision of the system with regards to its subscribers. As a consequence, Phoenix provides optimal event routing in both static and mobile client scenarios, and avoids mobility-related flooding of messages. Although the choice of Simple Routing sacrifices maximum scalability due to global propagation of subscriber interest, we show that several optimizations significantly minimize the loss of performance. In fact, when optimized, the performance of the Phoenix routing algorithm is suitable for the scenarios we envision: hybrid wireless networks for sensor/actuator deployments. Additionally, we note that our protocol can be extended to provide brokers with the ability to enforce client migrations for load-balancing purposes.

Mobile XSiena: towards mobile publish/subscribe

Mobile XSiena is a novel publish/subscribe platform which seeks to extend the XSiena content-based publish/subscribe system in order to support user mobility and create an experimental framework to study the relationship between such mobility and pervasive information dissemination flows.

Design and Evaluation of a Publish/Subscribe Framework for Ubiquitous Systems

This paper describes the design and evaluation of a novel publish/subscribe communication framework for ubiquitous systems and applications. The motivation of this work is the realization of the fact that the publish/subscribe communication model has several features that make it suitable to serve as a communication substrate for ubiquitous systems. In particular, we argue that a publish/subscribe framework that is scalable and supports client mobility is a valuable asset for the development of ubiquitous applications. We present a reference implementation, Phoenix, that supports the deployment of publish/subscribe components in mobile devices such as smartphones. In addition, we evaluate the functionality of Phoenix and its performance, in order to determine its operational constraints for server and mobile platforms.

Mobility-Enabled Publish/Subscribe: A Case Study

The integration of mobile devices within distributed systems introduces a wide range of constraints for developers. Some constraints arise from the hardware, software and interaction features of mobile platforms, while others stem from the use of wireless networks that are more dynamic, less reliable and performing than wired networks. In either case, software engineering processes have to tackle these constraints in order to provide mobility-enabled systems and applications. Based on first-hand experience in the field, this paper provides a framework to categorise these constraints and their severity, and describes some of the strategies that can be used to cope with them, with an emphasis in those relevant to middleware design.

Publish/Subscribe Systems in Tourism

Publish/subscribe is a communication paradigm that suits mobile application development due to the loosely coupled, asynchronous and anonymous communication mechanisms it involves. The Phoenix publish/subscribe system is a newly created communication middleware aimed at the tourism domain, representing both a tool for the experimental study of mobility and the development of value-added visitor-oriented tourism applications, including a real-time visitor tracking system and a location-based mobile tourist guide application. Initial validation of the Phoenix system has been carried out with positive results that will require additional validation.

Avoiding mobility-related message flooding in content-based publish/subscribe

We propose a routing algorithm for content-based publish/subscribe systems that supports client mobility without incurring in message flooding. Our protocol is based on the simple routing approach and requires brokers to maintain a global vision of the system with regards to its subscribers. The algorithm provides optimal event routing in both static and mobile client configurations, avoiding mobility-related flooding of messages. Although the choice of simple routing sacrifices maximum scalability due to global propagation of subscriber interest, several optimizations can minimize the loss of performance. Additionally, our migration algorithm can be extended to provide brokers with the ability to enforce client migrations in generic load-balancing scenarios.