Example: Use model transactions in a workflow

<project default="main">
  
  <!-- ANT Taskdefs for ant-contrib -->
  <taskdef resource="net/sf/antcontrib/antcontrib.properties"/>  
  
  <target name="loadModels">
    <epsilon.emf.register file="tree.ecore"/>    
    <epsilon.emf.loadModel name="M" modelfile="tree.model" 
        metamodeluri="Tree" read="false" store="true"/>
  </target>
  
  <target name="Transformation1">
    <epsilon.eol>
      <model ref="M"/>
      
      var t : new Tree;
      t.label = 't1';
      
    </epsilon.eol>
  </target>
  
  <target name="Transformation2">
    <epsilon.eol>
      <model ref="M"/>
      
      var t : new Tree;
      t.label = 't2';
      
    </epsilon.eol>
  </target>

  <target name="Validation1">
    <epsilon.evl>
      <model ref="M"/>
      
      context Tree {
        constraint C1 {
          check : true
        }
      }
      
    </epsilon.evl>
  </target>
  
  <target name="Validation2">
    <epsilon.evl>
      <model ref="M"/>
      
      context Tree {
        constraint C2 {
          check : true -- Switch to false to make validation fail
        }
      }
      
    </epsilon.evl>
  </target>
  
  <target name="Evaluation">
    <epsilon.eol>
      <model ref="M"/>
      
      Tree.all.size().println();
      
    </epsilon.eol>
  </target>
  
  <target name="main" depends="loadModels">
    <runtarget target="Transformation1"/>
    <runtarget target="Validation1"/>    
    
    <trycatch>
      <try>
        <!--Start a transaction on M so that we can roll it back later on.-->
        <epsilon.startTransaction name="Transaction1" models="M"/>
        <runtarget target="Transformation2"/>
        <runtarget target="Validation2"/>
        <!-- No errors in the validation. Commit the transaction.-->
        <epsilon.commitTransaction name="Transaction1"/>
      </try>
      <catch>
        <!--If validation fails, roll back the transaction.-->
        <epsilon.rollbackTransaction name="Transaction1"/>
      </catch>
    </trycatch>
    
    <runtarget target="Evaluation"/>
  </target>
  
</project>
						

@namespace(uri="Tree", prefix="Tree")
package Tree;

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

There are two ways to get the code of this example:

1. download the following zip archive(s), extract them and import them as new Eclipse projects
   • org.eclipse.epsilon.examples.workflow.transactions.zip
2. or check out the code from the SVN
   • go to the SVN repository
   • navigate to trunk/examples
   • check out the org.eclipse.epsilon.examples.workflow.transactions project