@Attribute(localName="result", type=AttributeType.QNAME)
  public abstract String getResult( JXPathContext context);
  public abstract boolean hasResult();
  
  /**
   * The variable of where to store the result.  If the variable does not yet exist, a variable will be declared. 
   */
  @Attribute(localName="variable", type=AttributeType.QNAME)
  public abstract String getVariable( JXPathContext context);
  public abstract boolean hasVariable();
  
  /**
   * The scope of the variable.
   * @see Scope
   */
  @Attribute(localName="scope", type=AttributeType.LITERAL, defaultValue="execution")
  public abstract Scope getScope(JXPathContext context);
  
  protected void storeValue(JXPathContext context, Object value) throws Exception {     
    if (hasResult()) {
      // TODO This should check that the path exists first.  If it doesn't exist, create it.
      context.setValue(getResult(context), value);
    } else if (hasVariable()) {
      ((ScopedQNameVariables)context.getVariables()).declareVariable( getVariable(context), value, getScope(context) );
    } else {
      throw new Exception("Result or Variable must be given.");
    }
  }