CKAN
CKAN (Comprehensive Knowledge Archive Network) is a data portal platform, that is, software for building a catalogue and repository for datasets. The system can store datasets, or simply hold metadata for datasets hosted externally. It provides discovery services such as keyword and map-based searching, and can harvest metadata from and syndicate its own metadata to other repositories.
Several providers offer hosted solutions, or the software may be downloaded and installed locally. For those taking the latter option, the CKAN team offers various support packages.
Provider
Open Knowledge Foundation.
Licensing and cost
CKAN is free and open source software, released under the GNU Affero GPL (General Public Licence) version 3.0.
The Open Knowledge Foundation offers hosting options on a monthly subscription basis, plus deployment and support contracts for organisations hosting their own installations. The costs are quoted on application, but several levels are offered depending on the scale of the installation.
Development Activity
CKAN version 2.2 was released in February 2014.
Development is ongoing at the time of writing.
Platform and interoperability
CKAN is most easily installed on a server running Ubuntu 12.04 LTS, for which pre-compiled packages are available. It may however be installed from source on many other platforms, since the technologies it uses – Python, PostgreSQL, Apache Solr, Jetty, Java – are cross-platform.
Filters have been written for harvesting metadata from other CKAN instances, CSW servers, WAFs (Web Accessible Folders), ArcGIS portals, Geoportal Servers, Z39.50 databases, DCAT (Data Catalog Vocabulary) RDF/XML sources, and various specific repositories. These can be used as templates for defining further filters. A CKAN instance can syndicate its metadata through CSW, RSS/Atom feeds, RDF (XML, N3), and CSV and JSON dumps.
An API is provided based on REST (Respresentational State Transfer) principles and JSON.
Functional notes
Data uploaded to CKAN can be public or private to a particular organisation. Uploaded data may be visualised using the built-in preview tools, and custom previewers may be added. Themes are available for changing the look and feel of the installation with relative ease.
Extensions are available for extending the functionality of CTAN in various ways, such as allowing users to comment on datasets, providing activity alerts on a per-dataset basis, and performing formal quality assurance checks.
Documentation and user support
The CKAN documentation website offers separate guides for users, administrators, installation maintainers, and developers. There are also a developer mailing list and a discussion mailing list, both of which show significant activity at the time of writing.
The Open Knowledge Foundation offers paid support in the form of consultancy, training, custom development, technical support (especially for upgrades) and priority/local bug fixes.
Usability
Day-to-day use of the system is through a straighforward web interface, while command-line tools are provided for technical maintenance tasks.
Expertise required
Little expertise is needed to use the system as an end user. Administering an installation is also relatively simple.
Installing, modifying and upgrading systems, however, requires some confidence in the technologies involved. Depending on the task involved that might involve familiarity with HTML, CSS, Python, or use of the command line.
Standards compliance
CKAN uses its own metadata scheme internally, but it may be extended with arbitrary metadata elements in key/value pairs. Support is included for geospatial data standards such as ISO 19139, UK GEMINI 2.1 and FGDC.
Influence and take-up
The CKAN website lists over 70 instances in use across the world, including national data portals for Australia, Austria, Canada, Italy, Norway, the Netherlands, Romania, Slovakia, the UK, and the USA.
