How do you invoke Stored Procedures?

<sql-query name="selectAllEmployees_SP" callable="true">
   <return alias="emp" class="employee">
     <return-property name="empid" column="EMP_ID"/>       

     <return-property name="name" column="EMP_NAME"/>       
     <return-property name="address" column="EMP_ADDRESS"/>
      { ? = call selectAllEmployees() }
   </return>
  </sql-query>