Equipe de recherche ZENITH
Data-intensive science such as agronomy, astronomy, biology and environmental science must deal with overwhelming amounts of experimental data produced through empirical observation and simulation. Such data must be processed (cleaned, transformed, analyzed) in all kinds of ways in order to draw new conclusions, prove scientific theories and produce knowledge. Similarly, digital humanities are faced with the problem of exploiting vast amounts of digitized cultural and historical data, such as broadcasted radio or TV content over decades. However, constant progress in scientific observational instruments (e.g. satellites, sensors, large hadron collider), simulation tools (that foster in silico experimentation) or digitization of new content by archivists create a huge data overload. For example, climate modeling data are growing so fast that they will lead to collections of hundreds of exabytes by 2020.
Scientific data is very complex, in particular because of heterogeneous methods used for producing data, the uncertainty of captured data, the inherently multi-scale nature (spatial scale, temporal scale) of many sciences and the growing use of imaging (e.g. molecular imaging), resulting in data with hundreds of attributes, dimensions or descriptors. Modern science research is also highly collaborative, involving scientists from different disciplines (e.g. biologists, soil scientists, and geologists working on an environmental project), in some cases from different organizations in different countries. Each discipline or organization tends to produce and manage its own data, in specific formats, with its own processes. Thus, integrating such distributed data gets difficult as the amounts of heterogeneous data grow.
Despite their variety, we can identify common features of scientific data: big data; manipulated through complex, distributed workflows; typically complex, e.g. multidimensional or graph-based; with uncertainty in the data values, e.g., to reflect data capture or observation; important metadata about experiments and their provenance; and mostly append-only (with rare updates).
Relational DBMSs, which have proved effective in many application domains (e.g. business transactions, business intelligence), are not efficient at dealing with scientific data or big data, which is typically unstructured. In particular, they have been criticized for their “one size fits all” approach. As an alternative , more specialized solutions are being developped such as NoSQL/NewSQL DBMSs and data processing frameworks (e.g. Spark) on top of distributed file systems (e.g. HDFS).
The three main challenges of scientific data management can be summarized by: (1) scale (big data, big applications); (2) complexity (uncertain, multi-scale data with lots of dimensions), (3) heterogeneity (in particular, data semantics heterogeneity). These challenges are also those of data science, with the goal of making sense out of data by combining data management, machine learning, statistics and other disciplines. The overall goal of Zenith is to address these challenges, by proposing innovative solutions with significant advantages in terms of scalability, functionality, ease of use, and performance. To produce generic results, these solutions are in terms of architectures, models and algorithms that can be implemented in terms of components or services in specific computing environments, e.g. cloud. We design and validate our solutions by working closely with our scientific application partners such as CIRAD, INRA and IRD in France, or the National Research Institute on e-medicine (MACC) in Brazil. To further validate our solutions and extend the scope of our results, we also foster industrial collaborations, even in non scientific applications, provided that they exhibit similar challenges.
Our approach is to capitalize on the principles of distributed and parallel data management. In particular, we exploit: high-level languages as the basis for data independence and automatic optimization; data semantics to improve information retrieval and automate data integration; declarative languages to manipulate data and workflows; and highly distributed and parallel environments such as P2P, cluster and cloud. We also exploit machine learning, probabilities and statistics for high-dimensional data processing, data analytics and data search. To reflect our approach, we organize our research program in five complementary themes:
Data integration, including data capture and cleaning;
Data management, in particular, indexing and privacy;
Scientific workflows, in particular, in grid and cloud;
Data analytics, including data mining and statistics;
Machine learning for high-dimensional data processing and search.
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