Writing a Data Query for an LOI¶
A data query is used to obtain the data required to answer the question template of the LOI.
Note
The data query will be executed on an external data repository that has a data adapter that integrates it with DISK.
The current implementation of DISK supports queries for data using SPARQL
as the query language.
Developers can extend DISK to integrate new data sources and create new data adapters.
Writing a Data Query in SPARQL¶
The starting point of the query are the Question Variables specified in the Question Template.
You can write the query by clicking on the Query text area.
The next example shows a data query for neuroscience data. The query follows several steps to obtain the data:
- Using the Question Variable
?Genotype
to find the?Cohort
- Using
?Cohort
to find the?dataset
- Using
?dataset
to find the?schema
- Using
?schema
to find?url
The query also includes at the end the Workflow Variable: Url that is passed as an input to the workflow of the LOI, as we describe next.
Specifying Workflows and Meta-Workflows¶
To specify the workflow of the LOI, you need to select the button Add Workflow and select the workflow from the list of workflows.
Next steps¶
In the next section, you will learn how to select workflows and select the workflow inputs.