Two projects to make XSD references possible in your Xtext grammar. This project uses the concepts explained in https://christiandietrich.wordpress.com/2011/07/17/xtext-2-0-and-uml/.

• Java 8
• Xtext
• Eclipse XML Schema Editor

• Import the org.eclipse.xtext.xsd and org.eclipse.xtext.xsd.ui projects into your workspace.
• Add the following required bundles to the MANIFEST.MF of your core Xtext DSL project:

org.eclipse.xtext.xsd,
org.eclipse.xtext.xsd.ui,
org.eclipse.xsd

• Add the following lines to your .mwe2 generate file:

Workflow {
  bean = org.eclipse.emf.mwe.utils.StandaloneSetup {
    scanClassPath = true
    platformUri = rootPath
    registerGeneratedEPackage = "org.eclipse.xsd.XSDPackage"
    registerGenModelFile = "platform:/resource/org.eclipse.xsd/model/XSD.genmodel"
  }
}

• Add the following import to your Xtext grammar file (.xtext):

import "http://www.eclipse.org/xsd/2002/XSD" as xsd

Note: Imports should be added between the grammar and generate declarations.

• Now your Xtext DSL can reference to elements defined in XSD files. For example, the following rule is now possible:

TypeInstance:
  'instance' name=ID ':' type=[xsd::XSDTypeDefinition|QN];
  
QN:
  ID ('.' ID)*;