Temporal Spatial-Keyword Top-k publish/subscribe

Massive amount of data that are geo-tagged and associated with text information are being generated at an unprecedented scale. These geo-textual data cover a wide range of topics. Users are interested in receiving up-to-date tweets such that their locations are close to a user specified location and their texts are interesting to users. For example, a user may want to be updated with tweets near her home on the topic “food poisoning vomiting.” We consider the Temporal Spatial-Keyword Top-k Subscription (TaSK) query. Given a TaSK query, we continuously maintain up-to-date top-k most relevant results over a stream of geo-textual objects (e.g., geo-tagged Tweets) for the query. The TaSK query takes into account text relevance, spatial proximity, and recency of geo-textual objects in evaluating its relevance with a geo-textual object. We propose a novel solution to efficiently process a large number of TaSK queries over a stream of geotextual objects. We evaluate the efficiency of our approach on two real-world datasets and the experimental results show that our solution is able to achieve a reduction of the processing time by 70-80% compared with two baselines.

SOPS: A System for Efficient Processing of Spatial-Keyword Publish/Subscribe

Massive amount of data that are geo-tagged and associated with text information are being generated at an unprecedented scale. These geo-textual data cover a wide range of topics. Users are interested in receiving up-to-date geo-textual objects (e.g., geo-tagged Tweets) such that their locations meet users’ need and their texts are interesting to users. For example, a user may want to be updated with tweets near her home on the topic “dengue fever headache.” In this demonstration, we present SOPS, the Spatial-Keyword Publish/Subscribe System, that is capable of efficiently processing spatial keyword continuous queries. SOPS supports two types of queries: (1) Boolean Range Continuous (BRC) query that can be used to subscribe the geo-textual objects satisfying a boolean keyword expression and falling in a specified spatial region; (2) Temporal Spatial-Keyword Top-k Continuous (TaSK) query that continuously maintains up-to-date top-k most relevant results over a stream of geo-textual objects. SOPS enables users to formulate their queries and view the real-time results over a stream of geotextual objects by browser-based user interfaces. On the server side, we propose solutions to efficiently processing a large number of BRC queries (tens of millions) and TaSK queries over a stream of geo-textual objects.

Herramientas de distribución de datos en un sistema Publish/Subscribe

El objetivo del presente trabajo es el desarrollo de una infraestructura de enrutamiento distribuida para un sistema publish/subscribe (en adelante pub/sub) que se incluirá en WireCloud, una plataforma para la composición de aplicaciones. Actualmente existen numerosas implementaciones de protocolos pub/sub en el mercado [3-6], y en este trabajo se hará un recorrido por aquellas con mayor relevancia, explicando sus características, ventajas y desventajas. De esta forma se podrán seleccionar aquellas cuyas prestaciones se adapten de la mejor forma posible a las necesidades de la plataforma. De entre todas las implementaciones existentes, algunas han sido simuladas para comprender mejor su funcionamiento. Esto permitió analizar las diferentes estrategias de enrutamiento de mensajes y qué estructuras de datos son las más óptimas para que el procesamiento de mensajes entrantes sea lo más rápido posible. Una vez que se determinó cuales son las estrategias y las estructuras de almacenamiento que mejor se adaptan a nuestro sistema, se ha procedido a la implementación real del sistema pub/sub en Java. Para cada uno de los módulos desarrollados se ha generado una serie de pruebas que permitirán comprobar el correcto funcionamiento de los componentes cuando se produzcan cambios o ampliaciones. Además, este trabajo también incluye el análisis e implementación de un nuevo protocolo de comunicación entre los diferentes componentes debido a que el existente era lento y pesado al consumir gran cantidad de recursos. El protocolo de comunicación analizado está basado en RMI (Remote Method Invocation), y aunque no mejoró la eficiencia con que los mensajes eran enviados si que permitió reducir en gran medida el consumo de recursos (CPU y memoria RAM). ------------------------------------------------------------ The goal of the current project is the development of a distributed pub/sub system to include it on WireCloud which is a platform to build compositional applications. Several implementations of pub/sub systems [3-6] have been developed until now and this project explains some of them, their characteristic, advantages and disadvantages. Thus, the implementations which better adapt to the project needs have been selected. Some of these implementations have been simulated to get a better knowledge of their behavior. The aim of these simulations was to select the best strategies to route messages and the optimal structures to reduce the computation time of a received message. After defining the better strategies and structures, the real pub/sub system have been finally developed in Java. For each developed module, a set of tests have been built to check its correct behavior in case of changes or extensions. Besides, the project also includes the analysis and the implementation of a new communication protocol among the different components because the existing one was slow and consumed a lot of computer resources. The new communication protocol is based in RMI (Remote Method Invocation) and has improved the consumption of resources. However, the efficiency of this new protocol was worse than the one of the existing protocol.

RCOS: Real time context sharing across a fleet of smart mobile devices

Today, biodiversity is endangered by the currently applied intensive farming methods imposed on food producers by intermediate actors (e.g.: retailers). The lack of a direct communication technology between the food producer and the consumer creates dependency on the intermediate actors for both producers and the consumers. A tool allowing producers to directly and efficiently market produce that meets customer demands could greatly reduce the dependency enforced by intermediate actors. To this end, in this thesis, we propose, develop, implement and validate a Real Time Context Sharing (RCOS) system. RCOS takes advantage of the widely used publish/subscribe paradigm to exchange messages between producers and consumers, directly, according to their interest and context. Current systems follow a topic-based model or a content-based model. With RCOS, we propose a context-awareness approach into the matching process of publish/subscribe paradigm. Finally, as a proof of concept, we extend the Apache ActiveMQ Artemis software and create a client prototype. We evaluate our proof of concept for larger scale deployment.

Real-time multi-model decadal climate predictions

We present the first climate prediction of the coming decade made with multiple models, initialized with prior observations. This prediction accrues from an international activity to exchange decadal predictions in near real-time, in order to assess differences and similarities, provide a consensus view to prevent over-confidence in forecasts from any single model, and establish current collective capability. We stress that the forecast is experimental, since the skill of the multi-model system is as yet unknown. Nevertheless, the forecast systems used here are based on models that have undergone rigorous evaluation and individually have been evaluated for forecast skill. Moreover, it is important to publish forecasts to enable open evaluation, and to provide a focus on climate change in the coming decade. Initialized forecasts of the year 2011 agree well with observations, with a pattern correlation of 0.62 compared to 0.31 for uninitialized projections. In particular, the forecast correctly predicted La Niña in the Pacific, and warm conditions in the north Atlantic and USA. A similar pattern is predicted for 2012 but with a weaker La Niña. Indices of Atlantic multi-decadal variability and Pacific decadal variability show no signal beyond climatology after 2015, while temperature in the Niño3 region is predicted to warm slightly by about 0.5 °C over the coming decade. However, uncertainties are large for individual years and initialization has little impact beyond the first 4 years in most regions. Relative to uninitialized forecasts, initialized forecasts are significantly warmer in the north Atlantic sub-polar gyre and cooler in the north Pacific throughout the decade. They are also significantly cooler in the global average and over most land and ocean regions out to several years ahead. However, in the absence of volcanic eruptions, global temperature is predicted to continue to rise, with each year from 2013 onwards having a 50 % chance of exceeding the current observed record. Verification of these forecasts will provide an important opportunity to test the performance of models and our understanding and knowledge of the drivers of climate change.

Communication Architecture Design for Real-Time Networked Control Systems

Networked control over data networks has received increasing attention in recent years. Among many problems in networked control systems (NCSs) is the need to reduce control latency and jitter and to deal with packet dropouts. This paper introduces our recent progress on a queuing communication architecture for real-time NCS applications, and simple strategies for dealing with packet dropouts. Case studies for a middle-scale process or multiple small-scale processes are presented for TCP/IP based real-time NCSs. Variations of network architecture design are modelled, simulated, and analysed for evaluation of control latency and jitter performance. It is shown that a simple bandwidth upgrade or adding hierarchy does not necessarily bring benefits for performance improvement of control latency and jitter. A co-design of network and control is necessary to maximise the real-time control performance of NCSs