# NTARC: A Data Model for the Systematic Review of Network Traffic Analysis Research
## 2 Scientific Data Repositories and Data Sharing Initiatives  
There are several projects aiming to host and promote research data repositories with a general, non-field-specific purpose; for example: B2 SHARE [9], Figshare [10], the Globus Data Publication service [11], 4 TU.Researchdata [12], the Zenodo platform [13], Dataverse [14], and Dryad [15]. [PERSON] et al. [16] wondered if generalist scientific data repositories were able to cope with the requirements of research data publishing and concluded that generalist repositories suffer from dealing with a multiplicity of data formats and topologies, a highly varied and multidisciplinary community of data owners and consumers, and a lack of consolidated and shared practices. Repositories were found viable, but conservative and in need of evolving. Such intrinsic heterogeneity seems to be a pressing problem to tackle in the near future to prevent underused repositories. When the research scope of a given repository is more specific, the heterogeneity problem is minimized. For instance, NASA's Common Metadata Repository (CMR) for Earth Science Data Information is a good example of a system developed to standardize and solve a past inefficient data retrieval situation. The use of Earth science data involves a community of Earth scientists, educators, government agencies, decision makers, and the general public. The CMR initiative has highly increased the value of past research and metadata [17]. The success of data repositories partially lies in creating metadata structures able to categorize and identify datasets and research objects effectively. In [18], [PERSON] et al. defined metadata as structured information that describes data content. Metadata explains the definition of measured and collected variables, their units, precision, accuracy, layout, transformations, limitations, etc. In addition, it should also clarify the data lineage, i.e., how data are measured, acquired, and preprocessed. Hence, metadata facilitates data sharing, access, and reuse. In addition--as claimed in [18]--metadata must be accessible in a format that is easily adaptable to technology changes, e.g., XML and JSON (used in NTARC). However, the adoption of data sharing practices and detailed metadata descriptions is still immature in the scientific community. [PERSON] et al. [19] recognized several challenges to face, mainly concerning the evolution of researchers' mindsets and habits. Nevertheless, the authors foresaw a near future in which data resources would be assessed similarly to journal publications in the scientist portfolio, increasing therefore both the quality and quantity of published data. Within the context of environmental sciences, [PERSON] et al. also presented a workflow to publish datasets, models, and model outputs, enabling the access, reuse, and citation of data products [19]. Scientific journals play an important role and endorse or directly develop platforms to improve how scientific publishable material is shared, managed, and reused. Dryad [15] publishes datasets related to peer-reviewed journal articles and scientifically reputable sources. In [20], [PERSON] and [PERSON] explored the concept of enhanced publications, meaning digital publications that incorporate ways to access and disseminate research materials beyond papers. They found that such initiatives are hindered by the fact that researchers must face several difficulties, e.g., manual efforts in curating data, preparing the material, or acquiring new skills to adapt their data, obtaining no obvious, direct benefits. Therefore, enhanced publications are more common when scientific journals demand such materials with clear policies. Similar conclusions and claims were exposed in the data journal survey in [21]. In [22], tools and digital environments were proposed to reduce costs and facilitate the creation of enhanced publications. In this line, Science Object Linking and Embedding (SOLE) [23] is a tool intended to enable reproducible research by linking research papers with associated science objects.