Overview

This is the Data API for the Knowledge Lake Management System developed in project STELAR. This REST API enables interaction with the Data Catalog, allowing users to publish datasets, search for datasets with various criteria (like keywords, spatial, or temporal) and also submit SPARQL queries against a Knowledge Graph.

Prerequisites

• This REST API assumes that a Data Catalog has been deployed using CKAN, including a PostgreSQL/PostGIS database where all metadata about published datasets (i.e., CKAN packages and resources) is maintained.

• A custom schema must have been created in the PostgreSQL database where the Data Catalog holds all metadata. Apart from metadata about published datasets (i.e., CKAN packages and resources), this database also hold metadata about workflow and task executions, as well as data profiling information.

• A Knowledge Graph must have been deployed via Ontop, employing mappings from the database to a virtual RDF graph that can be queried in SPARQL.

Creating and launching a Docker image

We provide an indicative Dockerfile that may be used to create a Docker image (data_api) from the source code:

$ docker build -t data_api .

Before deploying the API as a service, you must specify required parameters in a config.yaml file. Copy config-example.yaml to config.yaml and fill in values for all parameters specified in <...> (e.g., <API-PORT>, <CKAN-HOST>, credentials for connection to the underlying PostgreSQL database, etc.).

The docker image can then be used to launch a web service application at a specific port (e.g., 9055) as follows:

$ docker run --name data_api -p 9055:9055 data_api ./config.yaml

Once the service is launched, requests can be sent to this REST API in order to publish and search datasets in the data lake.

Documentation

Once the REST API is launched, full documentation about it will be available as an interactive HTML at: http://<DATA-API-HOST>/docs

Specifications

Data API supports OpenAPI 3.0 specification. Once the REST API is launched, full specifications will be readily available as a JSON at: http://<DATA-API-HOST>/specs. A copy of these specifications is available here.

License

The contents of this project are licensed under the Apache License 2.0.