Java REST client without schema

Question

Goal

Java client for Yahoo's HotJobs Resumé Search REST API.

Background

I'm used to writing web-service clients for SOAP APIs, where wsimport generates proxy stubs and you're off and running. But this is a REST API, which is new to me.

Details

• REST API
• No WADL
• No formal XML schema (XSD or DTD files). There are example XML request/response pairs.
• No example code provided

Progress

I looked at question Rest clients for Java?, but the automated solutions there assume you are providing both the server and the client, with JAXB invoked on POJOs to generate a schema and a REST API.

Using Jersey (a JAX-RS implementation), I have been able to make a manual HTTP request:

import com.sun.jersey.api.client.*;

...

ClientConfig clientConfig = new DefaultClientConfig();
Client client = Client.create(clientConfig);

WebResource webResource = client.resource("https://hj.yahooapis.com/v1/HJAuthTokens");
webResource.accept("application/xml");

// body is a hard-coded string, with replacements for the variable bits
String response = webResource.post(String.class, body);

// parse response into a org.w3c.dom.Document
// interface with Document via XPATH, or write my own POJO mappings

The response can look like:

<?xml version="1.0" encoding="utf-8"?>   
<Response>   
    <ResponseCode>0</ResponseCode>   
    <ResponseMessage>Login successful</ResponseMessage>
    <Token>NTlEMTdFNjk3Qjg4NUJBNDA3MkJFOTI3NzJEMTdDNDU7bG9jYWxob3N0LmVnbGJwLmNvcnAueWFob28uY29tO0pVNWpzRGRhN3VhSS4yQVRqRi4wWE5jTWl0RHVVYzQyX3luYWd1TjIxaGx6U0lhTXN3LS07NjY2MzM1OzIzNDY3NTsxMjA5MDE2OTE5OzZCM1RBMVNudHdLbl9VdFFKMFEydWctLQ==</Token>   
</Response>  

Or, it can look like:

<?xml version="1.0" encoding="utf-8"?>   
<yahoo:error xmlns:yahoo="http://www.yahooapis.com/v1/base.rng" xml:lang="en-US">   
    <yahoo:description>description</yahoo:description>   
    <yahoo:detail>   
        <ErrorCode>errorCode</ErrorCode>   
    </yahoo:detail>   
</yahoo:error>  

Questions

• Is there a way to auto-generate POJOs which can be marshalled/unmarshalled without a formal schema?
• Should I attempt to generate those POJOs by hand, with JAXB annotations?
• Is there some tool I should be leveraging so I don't have to do all this manually?

Answer 1

It's interesting that they provide an HTTP URL as the namespace URI for the schema, but don't actually save their schema there. That could be an oversight on their part, which an email or discussion-list posting could correct.

One approach is to create your own schema, but this seems like a lot of work for little return. Given how simple the messages are, I wonder if you even need a POJO to wrap them? Why not just have a handler that extracts the data you need using XPath?

---

Edit: blast from the past, but I saw the comment, reread the question, and realized that the first sentence was hard to understand. So, clarification:

One very good habit, if you're going to write a publicly accessible web service, is to make your schema document available at the same URL that you use for the schema's namespace URI -- or better, have that URL be a link to complete documentation (the W3C XSD namespace is itself a good example: http://www.w3.org/2001/XMLSchema).