Java Classes and Web Services

Objects that can be passed to and from web services have to be able to be serialized to an XML type, and then deserialized back to their original type. Objects that are automatically handled are Java primitive types and certain Java standard types, however if you want to create a web service using objects that are not automatically serialized, you can write your own custom serializer.

The objects that can be passed to and from web services are ones that conform to the JavaBean conventions For the purposes of web services, a JavaBean is any Java class that conforms to the following restrictions:

It must have a public default (zero argument) constructor
It must expose all attributes of interest as accessors
It must not matter what order the accessors for the properties (setMethod() and getMethod()) are in
Accessors must written in mixed case with a lower case first letter, for example, if an attribute is called name the accessors must be called getName and setName

For more information, refer to the JavaBean spec at http://java.sun.com/products/javabeans/reference/api/index.html.

Furthermore for web services, each property of the object must be of one of the Java types that maps to an XML schema simple type. These are listed in the table below, which shows the primitive XML Schema types and arrays of primitive XML Schema types supported as parameters and return values for web services. A service method can also accept and return a single piece of XML element data, passed as an org.w3c.dom.Element.

If you want to create a web service for a Java class that uses objects not described in this topic, for example char and char[], or java.util.Collection, you can write a custom serializer to handle the class properly. For more information, see Type Mapping by Hand at the end of this topic.

XML Schema type	Java type
string	java.lang.String
boolean	java.lang.Boolean
decimal	java.lang.Double
float	java.lang.Float
double	java.lang.Double
dateTime	java.util.Date
time	java.util.Date
date	java.util.GregorianCalendar
base64Binary	java.lang.Byte[]
normalizedString	java.lang.String
integer	java.lang.Integer
long	java.lang.Long
int	java.lang.Integer
short	java.lang.Short
byte	java.lang.Byte

Type Mapping by Hand

When a type described by the WSDL document cannot be understood by the Web Services Stub/Skeleton generator, an UnknownType placeholder is generated, and class will intentionally not compile. In addition, the generated stub class will contain some comments near the top of the file. To resolve this, you should do the type mapping by hand. You can write your own SOAP serializer/deserializer, which takes the Java type and converts it into a SOAP representation using SOAP encoding rules. You need to describe serializer/deserializer for each Java type in the web service deployment descriptor.

For more information about writing a customer serializer, see http://www.oracle.com/technology/tech/webservices/htdocs/samples/serialize/index.html.