<?xml version="1.0" encoding="UTF-8"?>

<vapor>
        <class name="Person">
                <attribute name="first_name" type="String" />
                <attribute name="last_name" type="String" />
                <attribute name="birthday" type="Date" />
                <attribute name="inhabits" type="Reference" index="true"/>
                <attribute name="friends" type="Reference" is_array="true" />
                <attribute name="nickNames" type="String" is_array="true" />
                <index>
                        <attribute name="first_name"/>
                        <attribute name="last_name"/>
                </index>
       </class>
       <class name="City">
               <attribute name="name" type="String" />
               <attribute name="altitude" type="Integer" />
               <unique>
                       <attribute name="name" />
                       <attribute name="altitude" />
               </unique>
      </class>

      <module name="University">
              <class name="Student" superclass="Person">
                      <attribute name="student_id" type="Integer" unique="true" />
             </class>
      </module>
</vapor>

