RESTful Web Services - Java SOA - page 486

Creating a POX over HTTP Service with Servlets
Problem
You want to get started writing RESTful web services without getting bogged down by an ex-
ternal framework. All you want is a class available at a URI that returns some XML.
Solution
Create a class that extends javax.servlet.http.HttpServlet ; make sure that you set the
response content type to text/xml . Use a transformer to write the XML out to your response.
Discussion
This is the simplest way to create an XML service without using any frameworks. For large-
scale solutions, you probably want to at least consider using one of the available frameworks
mentioned previously, but this approach represents the simplest thing that works.
In this example, you will define a servlet that returns XML to the requester. There is no
schema associated with the XML, and no interface definition such as a WSDL. In a real-world
service, this servlet would act as a frontend to some sort of enterprise information system.
Here I just mock that out with a ProductCatalog class that contains a list of Product in-
stances. The service itself consists of a servlet that invokes this “backend system” and trans-
forms the result to XML for the output stream of the response.
First let's look at the Product class because it uses no other class ( Example 8-1 ) .
Example8-1.Product.java
package com.soacookbook;
import javax.xml.bind.annotation.XmlType;
@XmlType
public class Product {
private String id;
private String name;
private double price;
public Product() { }
//Getters and Setters omitted...