Exposing EJBs as web services - EJB 3 in Action

Java Reference

In-Depth Information

UserService

In this example you'll expose a new createUser method on the UserService state-

less session bean. But instead of starting with Java objects, you'll start with the WSDL and

XSD files.

The existing createUser method on UserService takes a com.actionbazaar

.account.User object as input. This object is abstract; has subclasses Bidder , Em-

ployee , and SellerI ; and also has references to other objects. Auto-generating a web

service from such a complicated object may produce a WSDL with unexpected dependen-

cies and may be incompatible with other programming languages.

To avoid these problems, the new createUser method on UserService will use a

data transfer object (DTO). A DTO is a simplified version of your domain model objects

created specifically for interoperable data transfer. Because DTOs don't have complicated

object graphs, tools can handle them more easily. In this case, you'll start by creating the

XSD schema for a UserDTO object in the following listing.

Listing 8.3. Creating UserDTO.xsd

<?xml version="1.0" encoding="UTF-8"?>

<xs:schema

version="1.0"

targetNamespace="http://com.actionbazaar/user"

xmlns:xs="http://www.w3.org/2001/XMLSchema"

xmlns:tns="http://com.actionbazaar/user"

elementFormDefault="qualified">

<xs:element name="user" type="tns:UserDTO"/>

<xs:element name="createUserResponse" type="tns:CreateUserResponse"/>

<xs:complexType name="UserDTO">

<xs:sequence>

<xs:element id="firstName" name="firstName" type="xs:string"