Web Service - Start from Java

This section provides guidelines for designing an XML schema exported by a Java web service designed starting from Java. JAXB 2.0 provides a rich set of annotations and types for mapping Java classes to different XML Schema constructs. The guidelines provide guidance on using JAXB 2.0 annotations and types so that developer friendly bindings may be generated by XML serialization mechanisms (svcutil) on WCF client.

Not all JAXB 2.0 annotations are included here; not all are relevant from an interoperability standpoint. For example, the annotation @XmlAccessorType provides control over default serialization of fields and properties in a Java class but otherwise has no effect on the on-the-wire XML representation or the XML schema generated from a Java class. Select JAXB 2.0 annotations are therefore not included here in the guidance.

The guidance includes several examples, which use the following conventions:

• The prefix xs: is used to represent XML Schema namespace.

• JAXB 2.0 annotations are defined in javax.xml.bind.annotation package but, for brevity, the package name has been omitted.

Data Types

This section covers the following topics:

• Primitives and Wrappers

• BigDecimal Type

• java.net.URI Type

• Duration

• Binary Types

• XMLGregorianCalendar Type

• UUID Type

• Typed Variables

• Collections Types

• Array Types

Primitives and Wrappers

Guideline: Java primitive and wrapper classes map to slightly different XML schema representations. Therefore, .NET bindings will vary accordingly.

Example: A Java primitive type and its corresponding wrapper class

//-- Java code fragment
public class StockItem{
    public Double wholeSalePrice;
    public double retailPrice;
}

//--Schema fragment
<xs:complexType name="stockItem">
    <xs:sequence>
        <xs:element name="wholeSalePrice" type="xs:double" minOccurs="0"/>
        <xs:element name="retailPrice" type="xs:double"/>
    </xs:sequence>
</xs:complexType>

//-- .NET C# auto generated code from schema
public partial class stockItem
{
    private double wholeSalePrice;
    private bool wholeSalePriceFieldSpecified;
    private double retailPrice;

    public double wholeSalePrice
    {
        get{ return this.wholeSalePrice;}
        set{this.wholeSalePrice=value}
    }

    public bool wholeSalePriceSpecified
    {
        get{ return this.wholeSalePriceFieldSpecified;}
        set{this.wholeSalePriceFieldSpecified=value}
    }

    public double retailPrice
    {
        get{ return this.retailPrice;}
        set{this.retailPrice=value}
    }
}

//-- C# code fragment
stockItem s = new stockItem();
s.wholeSalePrice = Double.parse("198.92");
s.wholeSalePriceSpecified = true;
s.retailPrice = Double.parse("300.25");

BigDecimal Type

Guideline: Limit decimal values to the range and precision of .NET’s System.decimal.

java.math.BigDecimal maps to xs:decimal. .NET maps xs:decimal to System.decimal. These two data types support different range and precision. java.math.BigDecimal supports arbitrary precision. System.decimal does not. For interoperability use only values within the range and precision of System.decimal. (See System.decimal.Minvalue and System.decimal.Maxvalue.) Any values outside of this range require a customized .NET client.

Example: BigDecimal usage

//--- Java code fragment
public class RetBigDecimal {
    private BigDecimal arg0;

    public BigDecimal getArg0() { return this.arg0; }
    public void setArg0(BigDecimal arg0) { this.arg0 = arg0; }
}

//--- Schema fragment
<xs:complexType name="retBigDecimal">
    <xs:sequence>
        <xs:element name="arg0" type="xs:decimal" minOccurs="0"/>
    </xs:sequence>
</xs:complexType>

//--- .NET auto generated code from schema
public partial class retBigDecimal{
    private decimal arg0Field;
    private bool arg0FieldSpecified;

    public decimal arg0 {
        get { return this.arg0Field;}
        set { this.arg0Field = value;}
    }

    public bool arg0Specified {
        get { return this.arg0FieldSpecified;}
        set { this.arg0FieldSpecified = value;}
    }
}

//--- C# code fragment
System.CultureInfo engCulture = new System.CultureInfo("en-US");
retBigDecimal bd = new retBigDecimal();
bd.arg0 = System.decimal.MinValue;

retBigDecimal negBd = new retBigDecimal();
negBd = System.decimal.Parse("-0.0", engCulture);

java.net.URI Type

Guideline: Use the @XmlSchemaType annotation for a strongly typed binding to a .NET client generated with the DataContractSerializer.

java.net.URI maps to xs:string. .NET maps xs:string to System.string. Annotation @XmlSchemaType can be used to define a more strongly typed binding to a .NET client generated with the DataContractSerializer. @XmlSchemaType can be used to map java.net.URI to xs:anyURI. .NET’s DataContractSerializer and XmlSerializer bind xs:anyURI differently:

• DataContractSerializer binds xs:anyURI to .NET type System.Uri.

• XmlSerializer binds xs:anyURI to .NET type System.string.

Thus, the above technique only works if the WSDL is processed using DataContractSerializer.

Example: @XmlSchemaType and DataContractSerializer

// Java code fragment
public class PurchaseOrder
{
    @XmlSchemaType(name="anyURI")
     public java.net.URI uri;
}

//-- Schema fragment
<xs:complexType name="purchaseOrder">
    <xs:sequence>
        <xs:element name="uri" type="xs:anyURI" minOccurs="0"/>
    </xs:sequence>
</xs:complexType>

//--- .NET auto generated code from schema
//--- Using svcutil.exe /serializer:DataContractSerializer <wsdl file>
public partial class purchaseOrder : object,
        System.Runtime.Serialization.IExtensibleDataObject
{

    private System.Uri uriField;

    //-- ..... other generated code ........
    public System.Uri uri
    {
        get { return this.uriField; }
        set { this.uriField = value; }
    }
}

//--- C# code fragment
purchaseOrder tmpU = new purchaseOrder()
tmpU.uri = new System.Uri("../Hello", System.UriKind.Relative);

Example:@XmlSchemaType and XmlSerializer

// Java code fragment
public class PurchaseOrder
{
    @XmlSchemaType(name="anyURI")
    public java.net.URI uri;
}

//--- .NET auto generated code from schema
//--- Using svcutil.exe /serializer:XmlSerializer <wsdl file>
public partial class purchaseOrder
{
    private string uriField;
    public string uri
    {
        get { return this.uriField; }
        set { this.uriField = value; }
    }
}

//--- C# code fragment
purchaseOrder tmpU = new purchaseOrder()
tmpU.uri = "mailto:mailto:mduerst@ifi.unizh.ch";

Duration

Guideline: Use .NET’s System.Xml.XmlConvert to generate a lexical representation of xs:duration when the binding is to a type of System.string.

javax.xml.datatype.Duration maps to xs:duration. .NET maps xs:duration to a different datatype for DataContractSerializer and XmlSerializer.

• DataContractSerializer binds xs:duration to .NET System.TimeSpan.

• XmlSerializer binds xs:duration to .NET System.string.

When xs:duration is bound to .NET System.string, the string value must be a lexical representation for xs:duration. .NET provides utility System.Xml.XmlConvert for this purpose.

Example: Mapping xs:duration using DataContactSerializer

//-- Java code fragment
public class PurchaseReport {
     public javax.xml.datatype.Duration period;
}

//-- Schema fragment
<xs:complexType name="purchaseReport">
    <xs:sequence>
        <xs:element name="period" type="xs:duration" minOccurs="0"/>
    </xs:sequence>
</xs:complexType>

//-- .NET auto generated code from schema
//-- Using svcutil.exe /serializer:DataContractSerializer <wsdl file>
public partial class purchaseReport: object,
        System.Runtime.Serialization.IExtensibleDataObject
{
    private System.TimeSpan periodField;
    //-- ..... other generated code ........
    public System.TimeSpan period
    {
        get { return this.periodField; }
        set { this.periodField = value; }
    }
}

//-- C# code fragment
purchaseReport tmpR = new purchaseReport();
tmpR.period = new System.TimeSpan.MaxValue;

Example: Mapping xs:duration using XmlSerializer

//-- .NET auto generated code from schema
//-- Using svcutil.exe /serializer:XmlSerializer <wsdl file>
public partial class purchaseReport
{
    private string periodField;
    public string period
    {
        get { return this.periodField; }
        set { this.periodField = value; }
    }
}

//-- C# code fragment
purchaseReport tmpR = new purchaseReport();
tmpR.period = System.Xml.XmlConvert.ToString(new System.TimeSpan(23, 0,0));

Binary Types

Guideline: java.awt.Image, javax.xml.transform.Source, and javax.activation.DataHandler map to xs:base64Binary. .NET maps xs:base64Binary to byte[].

JAXB 2.0 provides the annotation @XmlMimeType, which supports specifying the content type, but .NET ignores this information.

Example: Mapping java.awt.Image without @XmlMimeType

//-- Java code fragment
public class Claim {
    public java.awt.Image photo;
}

//-- Schema fragment
<xs:complexType name="claim">
    <xs:sequence>
        <xs:element name="photo" type="xs:base64Binary" minOccurs="0"/>
    </xs:sequence>
</xs:complexType>

//-- .NET auto generated code from schema
public partial class claim : object,
        System.Runtime.Serialization.IExtensibleDataObject
{
    private byte[] photoField;
    //-- ..... other generated code .......
    public byte[] photo
    {
        get { return this.photoField; }
        set { this.photoField = value; }
    }
}

//-- C# code fragment
try
{
    claim tmpC = new claim();

    System.IO.FileStream f = new System.IO.FileStream(
        "C:\\icons\\circleIcon.gif", System.IO.FileMode.Open);
    int cnt = (int)f.Length;
    tmpC.photo = new byte[cnt];
    int rCnt = f.Read(tmpC.photo, 0, cnt);

}
catch (Exception e)
{
    Console.WriteLine(e.ToString());
}

Example: Mapping java.awt.Image with @XmlMimeType

//-- Java code fragment
public class Claim {
    @XmlMimeType("image/gif")
    public java.awt.Image photo;
}

//-- Schema fragment
<xs:complexType name="claim">
    <xs:sequence>
        <xs:element name="photo" ns1:expectedContentTypes="image/gif"
                    type="xs:base64Binary" minOccurs="0"
                    xmlns:ns1="http://www.w3.org/2005/05/xmlmime"/>
    </xs:sequence>
</xs:complexType>

//-- Using the @XmlMimeType annotation doesn’t change .NET 
//--auto generated code
public partial class claim : object,
        System.Runtime.Serialization.IExtensibleDataObject
{
    private byte[] photoField;
    //-- ..... other generated code .......
    public byte[] photo
    {
        get { return this.photoField; }
        set { this.photoField = value; }
    }
}

//-- This code is unchanged by the different schema
//-- C# code fragment
try
{
    claim tmpC = new claim();

    System.IO.FileStream f = new System.IO.FileStream(
        "C:\\icons\\circleIcon.gif", System.IO.FileMode.Open);
    int cnt = (int)f.Length;
    tmpC.photo = new byte[cnt];
    int rCnt = f.Read(tmpC.photo, 0, cnt);
}
catch (Exception e)
{
    Console.WriteLine(e.ToString());
}

XMLGregorianCalendar Type

Guideline: Use java.xml.datatype.XMLGregorianCalendar instead of java.util.Date and java.util.Calendar.

XMLGregorianCalendar supports the following XML schema calendar types: xs:date, xs:time, xs:dateTime, xs:gYearMonth, xs:gMonthDay, xs:gYear, xs:gMonth, and xs:gDay. It is statically mapped to xs:anySimpleType, the common schema type from which all the XML schema calendar types are dervived. .NET maps xs:anySimpleType to System.string.

java.util.Date and java.util.Calendar map to xs:dateTime, but don’t provide as complete XML support as XMLGregorianCalendar does.

Guideline: Use the annotation @XmlSchemaType for a strongly typed binding of XMLGregorianCalendar to one of the XML schema calendar types.

Example: XmlGregorianCalendar without @XmlSchemaType

//-- Java code fragment
public class PurchaseOrder {
    public javax.xml.datatype.XMLGregorianCalendar orderDate;
}

//-- Schema fragment
<xs:complexType name="purchaseOrder">
    <xs:sequence>
        <xs:element name="orderDate" type="xs:anySimpleType" minOccurs="0"/>
    </xs:sequence>
</xs:complexType>

//-- .NET auto generated code from schema
public partial class purchaseOrder
{
    private string orderDateField;
    public string orderDate
    {
        get { return this.orderDateField; }
        set { this.orderDateField = value; }
    }
}

//-- C# code fragment
purchaseOrder tmpP = new purchaseOrder();
tmpP.orderDate = System.Xml.XmlConvert.ToString(
   System.DateTime.Now, System.Xml.XmlDateTimeSerializerMode.RoundtripKind);

Example: XMLGregorianCalendar with @XmlSchemaType

//-- Java code fragment
public class PurchaseOrder {
    @XmlSchemaType(name="dateTime")
    public javax.xml.datatype.XMLGregorianCalendar orderDate;
}

//-- Schema fragment
<xs:complexType name="purchaseOrder">
    <xs:sequence>
        <xs:element name="orderDate" type="xs:dateTime" minOccurs="0"/>
    </xs:sequence>
</xs:complexType>

//-- .NET auto generated code from schema
public partial class purchaseOrder : object,
        System.Runtime.Serialization.IExtensibleDataObject
{
    private System.Runtime.Serialization.ExtensionDataObject extensionDataField;
    private System.DateTime orderDateField;

    public System.Runtime.Serialization.ExtensionDataObject ExtensionData
    {
        get { return this.extensionDataField; }
        set { this.extensionDataField = value; }
    }

    public System.DateTime orderDate
    {
        get { return this.orderDateField; }
        set { this.orderDateField = value; }
    }
}

//-- C# code fragment
purchaseOrder tmpP = new purchaseOrder();
tmpP.orderDate = System.DateTime.Now;

UUID Type

Guideline: Use Leach-Salz variant of UUID at runtime.

java.util.UUID maps to schema type xs:string. .NET maps xs:string to System.string. The constructors in java.util.UUID allow any variant of UUID to be created. Its methods are for manipulation of the Leach-Salz variant.

Example: Mapping UUID

//-- Java code fragment
public class ReportUid {
    public java.util.UUID uuid;
}

//-- Schema fragment
<xs:complexType name="reportUid">
    <xs:sequence>
        <xs:element name="uuid" type="xs:string" minOccurs="0"/>
    </xs:sequence>
</xs:complexType>

//-- .NET auto generated code from schema
public partial class reportUid: object,
        System.Runtime.Serialization.IExtensibleDataObject
{
    private System.Runtime.Serialization.ExtensionDataObject extensionDataField;
    private string uuidField;

    public System.Runtime.Serialization.ExtensionDataObject ExtensionData
    {
        get { return this.extensionDataField; }
        set { this.extensionDataField = value; }
    }

    public string uuid
    {
        get { return this.uuidField; }
        set { this.uuidField = value; }
    }
}

//-- C# code fragment
reportUid tmpU = new reportUid();
System.Guid guid = new System.Guid("06b7857a-05d8-4c14-b7fa-822e2aa6053f");
tmpU.uuid = guid.ToString();

Typed Variables

Guideline: A typed variable maps to xs:anyType. .NET maps xs:anyType to System.Object.

Example: Using a typed variable

// Java class
public class Shape <T>
{
    private T xshape;

    public Shape() {};
    public Shape(T f)
    {
        xshape = f;
    }
}

//-- Schema fragment
<xs:complexType name="shape">
    <xs:sequence>
        <xs:element name="xshape" type="xs:anyType" minOccurs="0"/>
    </xs:sequence>
</xs:complexType>

// C# code generated by svcutil
public partial class shape
{
    private object xshapeField;
    
    public object xshape
    {
        get { return this.xshapeField; }
        set { this.xshapeField = value; }
    }
}

Collections Types

Java collections types (java.util.Collection and its subtypes, array, List, and parameterized collection types such as List<Integer>) can be mapped to XML schema in different ways and can be serialized in different ways. The following examples show .NET bindings.

List of Nillable Elements

Guideline: By default, a collection type such as List<Integer> maps to an XML schema construct that is a repeating unbounded occurrence of an optional and nillable element. .NET binds the XML schema construct to System.Nullable<int>[]. The element is optional and nillable. However, when marshalling JAXB marshaller will always marshal a null value using xsi:nil.

Example: Collection to a list of nillable elements

//-- Java code fragment
@XmlRootElement(name="po")
public PurchaseOrder {
    public List<Integer> items;
}

//-- Schema fragment
<xs:element name="po" type="purchaseOrder">
<xs:complexType name="purchaseOrder">
    <xs:sequence>
        <xs:element name="items" type="xs:int" nillable="true"
                    minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
</xs:complexType>
...

//--- JAXB XML serialization
<po>
    <items> 1 </items>
    <items> 2 </items>
    <items> 3 </items>
</po>

<po>
    <items> 1 </items>
    <items xsi:nil=true/>
    <items> 3 </items>
</po>

//-- .NET auto generated code from schema
partial class purchaseOrder {
        private System.Nullable<int>[] itemsField;

    public System.Nullable<int>[] items
    {
        get { return this.itemsField; }
        set { this.itemsField = value; }    
    }
}

List of Optional Elements

Guideline: This is the same as above except that a collection type such as List<Integer> maps to a repeating unbounded occurrence of an optional (minOccurs="0") but not nillable element. This in turn binds to .NET type int[]. This is more developer friendly. However, when marshalling, JAXB will marshal a null value within the List<Integer> as a value that is absent from the XML instance.

Example: Collection to a list of optional elements

//-- Java code fragment
@XmlRootElement(name="po")
public PurchaseOrder {
    @XmlElement(nillable=false)
    public List<Integer> items;
}

//-- Schema fragment
<xs:element name="po" type="purchaseOrder">
<xs:complexType name="purchaseOrder">
    <xs:sequence>
        <xs:element name="items" type="xs:int"
                    minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
</xs:complexType>
...

// .NET auto generated code from schema
partial class purchaseOrder {
    private int[] itemsField;

    public int[] items
    {
        get { return this.itemsField; }
        set { this.itemsField = value; }    
    }
}

List of Values

Guideline: A collection such as List<Integer> can be mapped to a list of XML values (that is, an XML schema list simple type) using annotation @XmlList. .NET maps a list simple type to a .NET System.string.

Example: Collection to a list of values using @XmlList

//-- Java code fragment
@XmlRootElement(name="po")
public PurchaseOrder {
    @XmlList public List<Integer> items;
}

//-- Schema fragment
<xs:element name="po" type="purchaseOrder">
<xs:complexType name="purchaseOrder">
    <xs:element name="items" minOccurs="0">
        <xs:simpleType>
            <xs:list itemType="xs:int"/>
        </xs:simpleType>
    </xs:element>
</xs:complexType>
...

//-- XML serialization
<po>
    <items> 1 2 3 </items>
</po>

// .NET auto generated code from schema
partial class purchaseOrder {
    private string itemsField;

    public string items
    {
        get { return this.itemsField; }
        set { this.itemsField = value; }
    }
}

Array Types

Example: Single and multidimensional arrays

//-- Java code fragment
public class FamilyTree {
    public Person[] persons;
    public Person[][] family;
}

// .NET auto generated code from schema
public partial class familyTree
{
    private person[] persons;
    private person[][] families;

    public person[] persons
    {
        get { return this.membersField; }
        set { this.membersField = value; }
    }

    public person[][] families
    {
        get { return this.familiesField; }
        set { this.familiesField = value; }
    }
}

Fields and Properties

The following guidelines apply to mapping of JavaBeans properties and Java fields, but for brevity Java fields are used.

@XmlElement Annotation

Guideline: The @XmlElement annotation maps a property or field to an XML element. This is also the default mapping in the absence of any other JAXB 2.0 annotations. The annotation parameters in @XmlElement can be used to specify whether the element is optional or required, nillable or not. The following examples illustrate the corresponding bindings in the .NET client.

Example: Map a field or property to a nillable element

//-- Java code fragment
public class PurchaseOrder {

    // Map a field to a nillable XML element
    @javax.xml.bind.annotation.XmlElement(nillable=true)
    public java.math.BigDecimal price;
}

//-- Schema fragment
<xs:complexType name="purchaseOrder">
    <xs:sequence>
        <xs:element name="price" type="xs:decimal"
                    nillable="true" minOccurs="0" />
    </xs:sequence>
</xs:complexType>

// .NET auto generated code from schema
public partial class purchaseOrder {
    private System.Nullable<decimal> priceField;
    private bool priceFieldSpecified;

    public decimal price
    {
        get { return this.priceField; }
        set { this.priceField = value; }
    }

    public bool priceSpecified {
    {
        get { return this.priceFieldSpecified; }
        set { this.priceFieldSpecified = value;}
    }
}

Example: Map a property or field to a nillable, required element

//-- Java code fragment
public class PurchaseOrder {

    // Map a field to a nillable XML element
    @XmlElement(nillable=true, required=true)
    public java.math.BigDecimal price;
}

//-- Schema fragment
<xs:complexType name="purchaseOrder">
    <xs:sequence>
        <xs:element name="price" type="xs:decimal"
                    nillable="true" minOccurs="1" />
    </xs:sequence>
</xs:complexType>

// .NET auto generated code from schema
public partial class purchaseOrder {
    private System.Nullable<decimal> priceField;
    
    public decimal price
    {
        get { return this.priceField; }
        set { this.priceField = value; }
    }
}

@XmlAttribute Annotation

Guideline: A property or field can be mapped to an XML attribute using @XmlAttribute annotation. .NET binds an XML attribute to a property.

Example: Mapping a field or property to an XML attribute

//-- Java code fragment
public class UKAddress extends Address {
    @XmlAttribute
    public int exportCode;
}

//-- Schema fragment
<! XML Schema fragment -->
<xs:complexType name="ukAddress">
    <xs:complexContent>
        <xs:extension base="tns:address">
            <xs:sequence/>
            <xs:attribute name="exportCode" type="xs:int"/>
        </xs:extension>
    </xs:complexContent>
</xs:complexType>

// .NET auto generated code from schema
public partial class ukAddress : address
{
    private int exportCodeField;
    public int exportCode
    {
        get { return this.exportCodeField; }
        set { this.exportCodeField = value; }
    }
}

@XmlElementRefs Annotation

Guideline: @XmlElementRefs maps to a xs:choice. This binds to a property with name item in the C# class. If there is another field/property named item in the Java class, there will be a name clash that .NET will resolve by generating name. To avoid the name clash, either change the name or use customization, for example @XmlElement(name="foo").

Example: Mapping a field or property using @XmlElementRefs

//-- Java code fragment
public class PurchaseOrder {
    @XmlElementRefs({
        @XmlElementRef(name="plane", type=PlaneType.class),
        @XmlElementRef(name="auto", type=AutoType.class)})
    public TransportType shipBy;
}

@XmlRootElement(name="plane")
public class PlaneType extends TransportType {}

@XmlRootElement(name="auto")
public class AutoType extends TransportType { }

@XmlRootElement
public class TransportType { ... }

//-- Schema fragment
<!-- XML schema generated by wsgen -->
<xs:complexType name="purchaseOrder">
    <xs:choice>
        <xs:element ref="plane"/>
        <xs:element ref="auto"/>
    </xs:choice>
</xs:complexType>

<!-- XML global elements -->
<xs:element name="plane" type="autoType" />
<xs:element name="auto" type="planeType" />

<xs:complexType name="autoType">
    <!-- content omitted - details not relevant to example -->
</xs:complexType>

</xs:complexType name="planeType">
    <!-- content omitted - details not relevant to example -->
</xs:complexType>

// .NET auto generated code from schema
public partial class purchaseOrder {
    private transportType itemField;

    [System.Xml.Serialization.XmlElementAttribute("auto", typeof(autoType), Order=4)]
    [System.Xml.Serialization.XmlElementAttribute("plane", typeof(planeType), Order=4)]
    public transportType Item
    {
        get { return this.itemField; }
        set { this.itemField = value; }
    }

public partial class planeType { ... } ;
public partial class autoType { ... } ;

Java Classes

A Java class can be mapped to different XML schema type and/or an XML element. The following guidelines apply to the usage of annotations at the class level.

@XmlType Annotation - Anonymous Type

Guideline: Prefer mapping class to named XML schema type rather than an anonymous type for a better .NET type binding.

The @XmlType annotation is used to customize the mapping of a Java class to an anonymous type. .NET binds an anonymous type to a .NET class - one per reference to the anonymous type. Thus, each Java class mapped to an anonymous type can generate multiple classes on the .NET client.

Example: Mapping a Java class to an anonymous type using @XmlType

//-- Java code fragment
public class PurchaseOrder {
    public java.util.List<Item> item;
}
@XmlType(name="")
public class Item {
    public String productName;
    ...
}

//-- Schema fragment
<xs:complexType name="purchaseOrder">
    <xs:sequence>
        <xs:element name="item">
            <xs:complexType>
                <xs:sequence>
                    <xs:element name="productName" type="xs:string"/>
                </xs:sequence>
            </xs:complexType
>        </xs:element>
    </xs:sequence>
</xs:complexType>

// C# code generated by svcutil
public partial class purchaseOrder
{
    private purchaseOrderItem[] itemField;
    System.Xml.Serialization.XmlElementAttribute("item", 
        Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=true, Order=0)]
    public purchaseOrderItem[] item
    {
        get {
            return this.itemField;
        }

        set {
            this.itemField = value;
        }
    }
}

// .NET auto generated code from schema
public partial class purchaseOrderItem
{
    private string productNameField;
    public string productName {
        get { return this.productNameField; }
        set { this.productNameField = value; }
    }
}

@XmlType Annotation - xs:all

Guideline: Avoid using XmlType(propOrder=:{}).

@XmlType(propOrder={}) maps a Java class to an XML Schema complex type with xs:all content model. Since XML Schema places severe restrictions on xs:all, the use of @XmlType(propOrder={}) is therefore not recommended. So, the following example shows the mapping of a Java class to xs:all, but the corresponding .NET code generated by svcutil is omitted.

Example: Mapping a class to xs:all using @XmlType

//-- Java code fragment
@XmlType(propOrder={})
public class USAddress {
    public String name;
    public String street;
}

//-- Schema fragment
<xs:complexType name="USAddress">
    <xs:all>
        <xs:element name="name" type="xs:string"/>
        <xs:element name="street" type="xs:string"/>
        ...
    </xs:all>
</xs:complexType>

@XmlType Annotation - Simple Content

Guideline: A class can be mapped to a complexType with a simpleContent using @XmlValue annotation. .NET binds the Java property annotated with @XmlValue to a property with name "value".

Example: Class to complexType with simpleContent

//-- Java code fragment
public class InternationalPrice
{
    @XmlValue
    public java.math.BigDecimal price;
    
    @XmlAttribute public String currency;
}

//-- Schema fragment
<xs:complexType name="internationalPrice">
    <xs:simpleContent>
        <xs:extension base="xs:decimal">
            xs:attribute name="currency" type="xs:string"/>
        </xs:extension>
    </xs:simpleContent>
 </xs:complexType>

// .NET auto generated code from schema
public partial class internationalPrice
{
    private string currencyField;
    private decimal valueField;
    public string currency
    {
        get { return this.currencyField; }
        set { this.currencyField = value;}
    }

    public decimal Value
    {
        get { return this.valueField; }
        set { this.valueField = value;}
    }
}

Open Content

JAXB 2.0 supports the following annotations for defining open content. (Open content allows content not statically defined in XML schema to occur in an XML instance):

• The @XmlAnyElement annotation maps to xs:any, which binds to the .NET type System.Xml.XmlElement[].

• The @XmlAnyAttribute annotation maps to xs:anyAttribute, which binds to the .NET type System.Xml.XmlAttribute[].

Example: Using @XmlAnyElement for open content

//-- Java code fragment
@XmlType(propOrder={"name", "age", "oc"})
public class OcPerson {
    @XmlElement(required=true)
    public String name;
    public int age;

    // Define open content
    @XmlAnyElement
    public List<Object> oc;
}

//-- Schema fragment
<xs:complexType name="ocPerson">
    <xs:sequence>
        <xs:element name="name" type="xs:string"/>
        <xs:element name="age" type="xs:int"/>
        <xs:any minOccurs="0" maxOccurs="unbounded">
    </xs:sequence>
</xs:complexType>

// .NET auto generated code from schema
public class ocPerson
{
    private String name;
    private int age;
    private System.Xml.XmlElement[] anyField;<
    
    public String name { ... }
    public int age { ... }
    
    public System.Xml.XmlElement[] Any {
    {
        get { return this.anyField; }
        set { this.anyField = value; }
    }
}

Example: Using @XmlAnyAttribute for open content

//-- Java code fragment
@XmlType(propOrder={"name", "age"}
public class OcPerson {
    public String name;
    public int age;

    // Define open content
    @XmlAnyAttribute
    public java.util.Map oc;
}

//-- Schema fragment
<xs:complexType name="ocPerson">
    <xs:sequence>
        <xs:element name="name" type="xs:string"/>
        <xs:element name="age" type="xs:int"/>
    </xs:sequence>
    <xs:anyAttribute/>
</xs:complexType>

// .NET auto generated code from schema
public class ocPerson
{
    private String name;
    private double age;
    private System.Xml.XmlAttribute[] anyAttrField;<
    
    public String name { ... }
    public double age { ... }
    
    public System.Xml.XmlElement[] anyAttr {
    {
        get { return this.anyAttrField; }
        set { this.anyAttrField = value; }
    }
}

Enum Type

Guideline: A Java enum type maps to an XML schema type constrained by enumeration facets. This, in turn, binds to the .NET type enum type.

Example: Java enum -> xs:simpleType (with enum facets) -> .NET enum

//-- Java code fragment
public enum USState {MA, NH}

//-- Schema fragment
<xs:simpleType name="usState">
    <xs:restriction base="xs:string">
        <xs:enumeration value="NH" />
        <xs:enumeration value="MA" />
    </xs:restriction>
</xs:simpleType>

// .NET auto generated code from schema
public enum usState { NH, MA }

Package-level Annotations

The following package-level JAXB annotations are relevant from an interoperability standpoint:

• @XmlSchema – customizes the mapping of package to XML namespace.

• @XmlSchemaType – customizes the mapping of XML schema built-in type. The @XmlSchemaType annotation can also be used at the property/field level, as was seen in the example XMLGregorianCalendar Type.

@XmlSchema Annotation

A package is mapped to an XML namespace. The following attributes of the XML namespace can be customized using the @XmlSchema annotation parameters:

• elementFormDefault using @XmlSchema.elementFormDefault()

• attributeFormDefault using @XmlSchema.attributeFormDefault()

• targetNamespace using @XmlSchema.namespace()

• Associate namespace prefixes with the XML namespaces using the @XmlSchema.ns() annotation

These XML namespace attributes are bound to .NET serialization attributes (for example, XmlSerializer attributes).

Not Recommended Annotations

Any JAXB 2.0 annotation can be used, but the following are not recommended:

• The javax.xml.bind.annotation.XmlElementDecl annotation is used to provide complete XML schema support.

• The @XmlID and @XmlIDREF annotations are used for XML object graph serialization, which is not well supported.