## Basic usage

The examples below assume an SDO created with the schema and instance information shown below, using the XML Data Access Service.

The instance document below describes a single company, called 'MegaCorp', which contains a single department, called 'Advanced Technologies'. The Advanced Technologies department contains three employees. The company employeeOfTheMonth is referencing the second employee, 'Jane Doe'.

    <?xml version="1.0" encoding="UTF-8" ?>
    <company xmlns="companyNS" name="MegaCorp"
      employeeOfTheMonth="E0003">
      <departments name="Advanced Technologies" location="NY" number="123">
        <employees name="John Jones" SN="E0001"/>
        <employees name="Jane Doe" SN="E0003"/>
        <employees name="Al Smith" SN="E0004" manager="true"/>
      </departments>
    </company>

The root element of the schema is a company. The company contains departments, and each department contains employees. Each element has a number of attributes to store things like name, serial number, and so on. Finally, the company also has an IDREF attribute which identifies one of the employees as the 'employeeOfTheMonth'.

    <xsd:schema
      xmlns:xsd="http://www.w3.org/2001/XMLSchema"
      xmlns:sdo="commonj.sdo"
      xmlns:sdoxml="commonj.sdo/xml"
      xmlns:company="companyNS"
      targetNamespace="companyNS">
      <xsd:element name="company" type="company:CompanyType"/>
      <xsd:complexType name="CompanyType">
        <xsd:sequence>
          <xsd:element name="departments" type="company:DepartmentType"
            maxOccurs="unbounded"/>
        </xsd:sequence>
        <xsd:attribute name="name" type="xsd:string"/>
        <xsd:attribute name="employeeOfTheMonth" type="xsd:IDREF"
          sdoxml:propertyType="company:EmployeeType"/>
      </xsd:complexType>
      <xsd:complexType name="DepartmentType">
        <xsd:sequence>
          <xsd:element name="employees" type="company:EmployeeType"
            maxOccurs="unbounded"/>
        </xsd:sequence>
        <xsd:attribute name="name" type="xsd:string"/>
        <xsd:attribute name="location" type="xsd:string"/>
        <xsd:attribute name="number" type="xsd:int"/>
      </xsd:complexType>
      <xsd:complexType name="EmployeeType">
        <xsd:attribute name="name" type="xsd:string"/>
        <xsd:attribute name="SN" type="xsd:ID"/>
        <xsd:attribute name="manager" type="xsd:boolean"/>
      </xsd:complexType>
    </xsd:schema>

The XML Data Access Service maps the schema to an SDO. Attributes such as "name" become primitive properties, the sequence of employees becomes a many-valued containment relationship, and so on. Note that the containment relationships are expressed as one complex type within another, whereas non-containment references are expressed in terms of ID and IDREF, with a special sdoxml:propertyType attribute specifying the type of the non-containment reference.