when I open my .xmi file, I have bellow errors. Would you please help me in this regard?
org.eclipse.emf.ecore.xmi.PackageNotFoundException: Package with uri 'http://ruletypesmm/1.0' not found.
org.eclipse.emf.ecore.xmi.ClassNotFoundException: Class 'Trafo' is not found or is abstract.
You've provided minimal information, so you can't expect much help. The Ecore package needed to read this XMI isn't available. You either need to install the bundle that provides the generated model for this namespace or your XMI instance needs to specify, via an xsi:schemaLocation attribute, the location where this Ecore package can be loaded.