GeoServer does not come built-in with support for GML; it must be installed through an extension. Proceed to Installing the GML extension for installation details.
Currently the GML extension is unmaintained and carries unsupported status. While still usable, do not expect the same reliability as with other extension.
Geographic Markup Language (GML) is a XML based format for representing vector based spatial data.
Currently GML version 2 is supported.
Installing the GML extension¶
Download the GML extension from the GeoServer download page.
Make sure to match the version of the extension to the version of the GeoServer instance!
Extract the contents of the archive into the WEB-INF/lib directory of the GeoServer installation.
Adding a GML data store¶
Once the extension is properly installed GML will be an option in the Vector Data Sources list when creating a new data store.