Gabriel Guerrero-Contreras

A Context-Aware Architecture Supporting Service Availability in Mobile Cloud Computing

Mobile systems are gaining more and more importance, and new promising paradigms like Mobile Cloud Computing are emerging. Mobile Cloud Computing provides an infrastructure where data storage and processing could happen outside the mobile node. Specifically, there is a major interest in the use of the services obtained by taking advantage of the distributed resource pooling provided by nearby mobile nodes in a transparent way. This kind of systems is useful in application domains such as emergencies, education and tourism. However, these systems are commonly based on dynamic network topologies, in which disconnections and network partitions can occur frequently, and thus the availability of the services is usually compromised. Techniques and methods from Autonomic Computing can be applied to Mobile Cloud Computing to build dependable service models taking into account changes in the context. In this work, a context-aware software architecture is proposed to support the availability of the services deployed in mobile and dynamic network environments. The proposal is based on a service replication scheme together with a self-configuration approach for the activation/hibernation of the replicas of the service depending on relevant context information from the mobile system. To that end, an election algorithm has been designed and implemented.

Dynamic Replication and Deployment of Services in Mobile Environments

Currently, mobile environments are gaining importance, and new promising paradigms, like Mobile Cloud, are arising. However, these environments pose new challenges and are mainly characterized, among others, by frequent changes in their execution context. This particularly is challenging for software architects in the design and implement this kind of systems. For instance, the Service Oriented Architecture (SOA) paradigm has not been devised to operate in dynamic network environments, where centralized services or static deployments must be avoided, in order to provide a higher availability of services. Therefore, in order to provide a reliable SOA implementation in mobile environments, it must be complemented with techniques and methods of Autonomic Computing. In this work, a self-adaptive SOA approach is proposed. This architecture will provide support to the dynamic replication and deployment of services in mobile environments. The approach is based on the context information modelling and management as key aspect to achieve the required architecture adaptation.

Designing a Service Platform for Sharing Internet Resources in MANETs

Nowadays, there is great interest to develop future Internet applications supporting resource sharing in mobile networks. This usually entails maintaining the consistency of those shared resources, that is, between different replicas of the resources. Moreover, mobile networks are characterized by varying capacity, in part, caused by their mobility, which also derives in frequent networking disconnections and network partitions. Therefore, to ensure the consistency of replicated resources being shared in a mobile network is more complicated that in networks with infrastructure support, as it requires to process events associated with the use of the resources themselves as well as those related with the state of the network. In response, in this paper an event-driven platform consisting of two services (monitoring and synchronization) and an underlying middleware has been designed in order to address the consistency of shared Internet resources in mobile networks in a simple way. The synchronization service only needs to be specialized to adapt the resource, depending on its type, to the required use in a particular system. The proposal is illustrated through the example of a collaborative document editor.

A Collaborative Semantic Annotation System in Health: Towards a SOA Design for Knowledge Sharing in Ambient Intelligence

People nowadays spend more and more time performing collaborative tasks at anywhere and anytime. Specifically, professionals want to collaborate with each other by using advanced technologies for sharing knowledge in order to improve/automatize business processes. Semantic web technologies offer multiple benefits such as data integration across sources and automation enablers. The conversion of the widespread Content Management Systems into its semantic equivalent is a relevant step, as this enables the benefits of the semantic web to be extended. The FLERSA annotation tool makes it possible. In particular, it converts the Joomla! CMS into its semantic equivalent. However, this tool is highly coupled with that specific Joomla! platform. Furthermore, ambient intelligent (AmI) environments can be seen as a natural way to address complex interactions between users and their environment, which could be transparently supported through distributed information systems. However, to build distributed information systems for AmI environments it is necessary to make important design decisions and apply techniques at system/software architecture level. In this paper, a SOA-based design solution consisting of two services and an underlying middleware is combined with the FLERSA tool. It allows end-users to collaborate independently of technical details and specific context conditions and in a distributed, decentralized way.

Consistent Management of Context Information in Ubiquitous Systems

In context-aware systems, where the context information tends to be distributed and/or replicated, can be decisive to maintain the correctness of this information, owing to the decisions in context-aware systems are taken on the basis of it. In ubiquitous environments, new challenges are emerging, which can affect to the consistent management of the distributed context information. For instance, the dynamism is a feature that directly affects the availability of the resources deployed in the network, among other quality features, and it implies additional design and development efforts from software engineers. Service Oriented Architecture (SOA), together with replication techniques may help to improve resource availability and strengthen the system against node disconnections, nevertheless, additional techniques must be applied to ensure the consistency of the distributed/replicated resources. In this paper, an approach to support, from the software design stage, the synchronization and consistency management of context information is introduced. This approach follows the SOA model, and provides a common basis for the synchronization of distributed/replicated resources. A case study, related with an ubiquitous system deployed in a hospital where context-aware services can be found, will be described in order to show the feasibility of the proposal.

Integrating a Dual Method on a General Architecture to Self-Adaptive Monitoring Systems

The socio-economic, demographic and the advances in technology are driving the development of software systems alleviating deficiencies and providing satisfactory solutions. These systems are increasing their size, complexity and heterogeneity, and new approaches are required to support a dynamic self-adaptation at run time. This ability can be obtained from context information which should be monitored by motes and adequately interpreted depending on where it was taken from. On the basis of the foregoing, in this work a dual method on a general architecture to develop self-adaptive monitoring systems is proposed. This provides support to enrich the knowledge of a specific case from two different perspectives, based on the knowledge of the general domain and from the motes deployed by the other specific cases.

Impact of Transmission Communication Protocol on a Self-adaptive Architecture for Dynamic Network Environments

The quality attributes of services deployed on distributed system are critically conditioned by their placement within the distributed system. To this regard, the host election process is one of the main elements in the self-adaptive replication and deployment of services, as one of the possible approaches to address the changing computational conditions of dynamic network environments in order to ensure quality attributes of the system. In this paper, a study and an analysis of the behaviour of a host election algorithm under reliable and non-reliable transmission protocols (TCP and UDP) is presented. The algorithm has been proposed as a basis for a self-adaptive architecture in previous work. The results demonstrate that the reliability of TCP redound in a better efficiency in the system, despite its high latency and higher consumption of bandwidth, in comparison to UDP.

BaaS-4US: A Framework to Develop Standard Backends as a Service for Ubiquitous Applications

Internet of Things (IoT) is presented as the next computing and interaction paradigm to be implemented in society, after current advances in Web, mobile and cloud-based technologies. However, there are still a large number of open challenges to be addressed for its successful deployment. Many proposals are focused on hardware and low-level technical issues, but the use of software design based techniques/methods can also provide significant advantages in terms of an easier development of IoT applications. This research work introduces a framework intended to facilitate the development of backend service platforms based on standards. It follows the ideas behind the Internet of Services (IoS) paradigm and cloud computing. And the main purpose of this contribution is to provide a Web Services deployment via their behaviour specification which is independent of actual and future technologies / standards.

Self-adaptive deployment of services in mobile environments: a study of the communication reliability on the host election algorithm

Self-adaptive service deployment and replication are one of the possible approaches to address the changing computational conditions of mobile-based environments in order to ensure certain quality attributes of the system. The host election for the dynamic placement of service replicas is one of the main steps in the process to ensure the availability, reliability and performance in mobile distributed systems. The reliability of the host election algorithm is essential for the proper functioning of these systems. However, its distributed execution may be affected by the dynamic conditions of the mobile network. This paper presents an analysis of the reliability of an election algorithm on the basis of two different transmission protocols: TCP, a reliable protocol, and UDP, a non-reliable transmission protocol. The election algorithm is part of a self-adaptive architecture designed to address the availability of the services deployed in dynamic mobile network environments.

Self-adaptive Service Deployment in Context-Aware Systems

Ubiquitous environments present a dynamic network topology which implies frequent context changes which can affect the availability of the services deployed in the system. In order to obtain the full potential that this kind of environments can provide to assist human beings, this challenge must be faced. Service replication models in combination with self-adaptive capabilities may help to improve service availability and strengthen the system. In this work, it is presented a conceptual model to support a run-time service deployment taking into consideration relevant context information, such as resource availability, network topology and service requirements.