In order to exchange and interoperate metadata with other data centers, DRRKS deploys pycsw tool to publish metadata.
Pycsw is the Python language implementation of OGC CSW server, and is also the CSW tool recommended by OGC. Because pycsw uses many open source geospatial libraries, it is easier to install under the Linux operating system. In practical use, Debian Linux is deployed with Python 3.5 runtime environment.
Unlike other CSW servers, pycsw has the ability to implement distributed search on its own. When pycsw is enabled, pycsw searches all specified directories and returns a unified set of search results to the client. pycsw deployment has three configurations (CSW-1, CSW-2, CSW-3), and also provides three endpoints. Each endpoint is based on an opaque metadata repository (subject/location/discipline, etc.). The goal is to perform one-to-one searches for all endpoints. pycsw has the ability to perform server-side repository or database filtering to cover all CSW requests. The purpose of pycsw is to query a specific subset of metadata repository and return specific query results.