Figure 2

Djeen data organization model. Djeen separates Projects hierarchy, Templates and Annotations on one side (these are stored in the Djeen relational database) and the data itself (stored in the file system). Data stored into the database are divided into several objects, each of them being represented by a database table, linked to a class model in the MVC architecture. Project is the primary Djeen organizational element. It allows the construction of a hierarchical tree of sub-Projects and includes metadata about itself and stored files. The File object is the most basic and central piece of information within Djeen, since it represents the lowest granularity level in most high-throughput analyses. This project/files hierarchical tree is structurally mirrored into the file system. Metadata are divided into Characteristics (related to Projects) and Annotations (related to Files). Those two types of metadata can be saved into Templates, allowing users to reuse them into other Projects. The Users object is a specific table containing user and group information. It supersedes the Joomla! system by formation specific to Djeen that allows managing specific permissions and groups while permitting reuse of all the features already implemented in the CMS, such as authentication or e-mailing.