Demo Atom package associating a custom file extension with a new grammar derived from text.xml, an XML schema and rule settings for validation and autocomplete with linter-autocomplete-jing.
A custom grammar with the scope name text.xml.demoxy specifying the extension .demoxyext
A schema used for validation and autocomplete
A settings file providing a rule to associate the schema at schemata/demoxy.rng with the grammar scope text.xml.demoxy
A test XML file
This package is not published in the Atom Package Repository; to use it as a template or demo, clone the project from GitHub, run apm link from the project's root directory and make sure linter-autocomplete-jing is installed in Atom.
In case you want to specify validation rules for files with common XML extensions (as defined in the language-xml package) you can omit the grammar definition in grammars.
A more detailed description of the validation rules is available at https://github.com/aerhard/linter-autocomplete-jing/blob/master/README.md#schema-rules.