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XML to EMF Transformation with ETL

This example shows how to transform an XML document into an EMF model using the Epsilon Transformation Language and Epsilon's XML driver. We start with our source XML file (tree.xml), which is shown below:

<?xml version="1.0"?>
<tree name="t1">
    <tree name="t2"/>
    <tree name="t3">
        <tree name="t4"/>
    </tree>
</tree>

The Ecore metamodel (expressed in Emfatic) to which our target EMF model will conform to is shown below:

package tree;

class Tree {
    attr String label;
    ref Tree#children parent;
    val Tree[*]#parent children;
}

Finally, our ETL transformation (xml2emf.etl) is in the listing below:

rule XmlTree2EmfTree
    transform s : Xml!t_tree
    to t : Emf!Tree {

    t.label = s.a_name;
    t.children ::= s.c_tree;

}

The transformation consists of one rule which transforms every tree element in the XML document (Xml!t_tree) into an instance of the Tree class of our Ecore metamodel above. The rule sets the label of the latter to the name of the former, and the children of the latter, to the equivalent model elements produced by the tree child elements of the former.

To run the transformation:

  • Right-click on tree.emf or tree.ecore and select Register EPackages
  • Right-click on xml2emf.launch and select Run As → xml2emf

Once the transformation has executed you can open tree.model to inspect the EMF model it has produced with the reflective tree-based editor. The complete source code of the example is available here.