The Environmental Data Commons’ (EDC) data dictionary provides the first level of validation for all data stored in and generated by the EDC. Written in YAML, JSON schemas define all the individual entities (nodes) in the EDC data model. Moreover, these schemas define all of the relationships (links) between the nodes. Finally, the schemas define the valid key-value pairs that can be used to describe the nodes.
The EDC Data Model covers all of the nodes within the EDC as well as the relationships between
the different types of nodes. All of the nodes in the data model are strongly typed and individually
defined for a specific data type. For example, submitted files can come in different forms, such as
aligned or unaligned reads; within the model we have two separately defined nodes for
Submitted Unaligned Reads and Submitted Aligned Reads. Doing such allows for faster querying of
the data model as well as providing a clear and concise representation of the data in the EDC.
Beyond node type, there are also a number of EDC extensions used to further define the nodes within
the data model. Nodes are grouped up into categories that represent broad roles for the node such
as analysis or biospecimen. Additionally, nodes are defined within their Program or Project
and have descriptions of their use. All nodes also have a series of systemProperties; these
properties are those that will be automatically filled by the system unless otherwise defined by
the user. These basic properties define the node itself but still need to be placed into the model.
The model itself is represented as a graph. Within the schema are defined links; these links
point from child to parent with Program being the root of the graph. The links also contain a
backref that allows for a parent to point back to a child. Other features of the link include a
semantic label that describes the relationship between the two nodes, a multiplicity property
that describes the numeric relationship from the child to the parent, and a requirement property
to define whether a node must have that link. Taken all together the nodes and links create the
directed graph of the EDC Data Model.
Each node contains a series of potential key-value pairs (properties) that can be used to
characterize the data they represent. Some properties are categorized as required or preferred.
If a submission lacks a required property, it cannot be accepted. Preferred properties can denote
two things: the property is being highlighted as it has become more desired by the community or
the property is being promoted to required. All properties not designated either required or
preferred are still sought by EDC, but submissions without them are allowed.
The properties have further validation through their entries. Legal values are defined in each
property. For the most part these are represented in the enum categories although some keys,
such as submitter_id, will allow any string value as a valid entry. Other numeric properties
can have maximum and minimum values to limit valid entries. For examples of what a valid entry
would look like, each node has a mock submission located in the examples/valid/ directory.