ArcGIS is a comprehensive metadata registry and data repository. You can easily organize your content by themes, groups, and provide curated content catalogs through Hub + Enterprise Sites. Many governments and regional organizations need to publish their metadata into other catalogs like Data.gov or similar CKAN instances. Now you can integrate your ArcGIS Sites with other registries through data feeds. ArcGIS includes support for several common formats like DCAT, and you can build your own with the open-source Koop.js project.