The workflow ties together model, meta model and templates and defines the process of how to generate code.
To create a new workflow file, switch to the Xpand/Xtend perspective, click on "File", "New" and "Workflow file" . After specifying a folder and a filename an empty workflow is created.
The minimalistic approach consists of two steps:
Read the Model: This is done by 
        org.eclipse.xtend.typesystem.xsd.XMLReader  . It needs
        exactly one uri element which defines the XML
        file. A further nested element of type 
        org.eclipse.xtend.typesystem.xsd.XSDMetaModel  tells the
        XMLReader which metamodel to use.
        XSDMetaModel can contain multiple
        schemaFile elements. How the schemas are used
        for the XML file is determined based on the declared namespaces.
        modelSlot defines a location where the model is
        stored internally, this is like a variable name which becomes
        important if you want to handle multiple models within the same
        workflow.
Generate Code: This part just does the regular code generation
        using Xpand and is not specific to the Xpand XSD Adapter at all. The
        generator  org.eclipse.xpand2.Generator  needs
        to know which meta model to use. This example references the
        previously declared one. The expand element
        tells the generator to call the definition named
        Root within file
        template.xpt using the contents of slot
        model as parameter. Element
        outlet defines where to store the generates
        files.
<workflow>
  <component class="org.eclipse.xtend.typesystem.xsd.XMLReader">
    <modelSlot value="model" />
    <uri value="model.xml" />
    <metaModel id="mm"
      class="org.eclipse.xtend.typesystem.xsd.XSDMetaModel">
      <schemaFile value="metamodel.xsd" />
    </metaModel>
  </component>
  <component class="org.eclipse.xpand2.Generator">
    <metaModel idRef="mm" />
    <expand value="template::Root FOR model" />
    <outlet path="src-gen" />
  </component>
</workflow>