Semantic difference between element and complexType in XSD

Question

Given this XSD:

<xsd:element name="ServiceList">
    <xsd:complexType>
        <xsd:sequence>
            ...
        </xsd:sequence>
    </xsd:complexType>
</xsd:element>

<xsd:complexType name="ServiceList">
    <xsd:sequence>
        ...
    </xsd:sequence>
</xsd:complexType>

What is kind of the semantic difference between these two? I.e. named elements and complexTypes which are direct children of a schema.

The reason for me asking is that I tried doing this in an XSD:

<xsd:element name="AvailableServices" type="cm:ServiceList" />
<xsd:element name="ExistingServices" type="cm:ServiceList" />
<xsd:complexType name="ServiceList">
    <xsd:sequence>
        ...
    </xsd:sequence>
</xsd:complexType>

But when this was compiled into Java classes using the Maven JAXB plugin, I am only able to create a new ServiceList(). AvailableServices and ExistingServices doesn't seem to even exist among the generated classes. So, what's going on here?

Answer 1

Classes Correspond to Complex Types

In JAXB (JSR-222) Java classes correspond to complex types. Named complex types and anonymous complex types of global elements correspond to root level classes. Nested complex types by default are generated as static inner classes. You can change this default behaviour:

• https://stackoverflow.com/a/13175419/383861

Global Elements

If a global element is uniquely associated with a complex type (global element with anonymous complex type) it will be annotated with @XmlRootElement. Global elements that correspond to global types will correspond to @XmlElementDecl annotations in the ObjectFactory class.

For More Information

• http://blog.bdoughan.com/2012/07/jaxb-and-root-elements.html