Required attribute
File: Data.xml <?xml version="1.0"?> <images xmlns="http://www.java2s.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.java2s.com Schema.xsd"> <image href="http://www.java2s.com/Style/Logo.png"/> </images> File: Schema.xsd <?xml version="1.0"?> <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.java2s.com" xmlns="http://www.java2s.com" elementFormDefault="qualified"> <xsd:element name="images"> <xsd:complexType> <xsd:sequence> <xsd:element name="image" maxOccurs="unbounded"> <xsd:complexType> <xsd:attribute name="href" type="xsd:anyURI" use="required"/> </xsd:complexType> </xsd:element> </xsd:sequence> </xsd:complexType> </xsd:element> </xsd:schema>