Chapter 3 from REST O'Reiley Book Issue

[Mike London]

Hello,

I'm having an issue getting even the basic REST example from the Chapter 3 ("Restful Java with JAX-RS") code to work.
It looks like everything is set up correctly, and I've spent the requisite 40 or so (mind-numbing, hair pulling, head banging against the table, etc.) hours
wresting with what "should" be simple code to get working.

The basic idea is that you would do a POST to add a new customer to the service's internal Java ConcurrentHashMap.

So, the service has the service side and the testing side. The author of the book uses maven and test cases and all works (of course) fine in the book.

I'm really starting to wonder how many people are using REST, because it seems incredibly difficult to get working.

=================

Here's the server logic (note that even the constructor log4j output is not writing an initial message).

package services;

import domain.Customer;
import org.apache.log4j.Logger;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;

import javax.ws.rs.*;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.StreamingOutput;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintStream;
import java.net.URI;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicInteger;

@Path("/customers")
public class CustomerResourceService
{
    public CustomerResourceService()
    {
        log.debug("Inside WS Constructor!");  // doesn't happen on tomcat restart or running test code below
    }

    // setup Logging using Log4j
    private static org.apache.log4j.Logger log = Logger.getLogger(CustomerResourceService.class);

    private Map<Integer, Customer> customerDB = new ConcurrentHashMap<Integer, Customer>();
    private AtomicInteger idCounter = new AtomicInteger();

    // creating Customers
    @POST
    @Consumes("application/xml")
    public Response createCustomer(InputStream is)
    {
        log.debug(Inside customers method now.");

        Customer customer = readCustomer(is);
        customer.setId(idCounter.incrementAndGet());
        customerDB.put(customer.getId(), customer);
        System.out.println("Created Customer " + customer.getId());
        return Response.created(URI.create("/customers/" + customer.getId())).build();
    }

    // Retrieve Customers. Id is the customer code.
    @GET
    @Path("{id}")
    @Produces("application/xml")
    public StreamingOutput getCustomer(@PathParam("id") int id) throws Exception
    {
        log.debug("Inside streamingOutput!, Customer DB size: " + customerDB.size());

        final Customer customer = customerDB.get(id);

        if (customer == null)
        {
           throw new WebApplicationException(Response.Status.NOT_FOUND); // throws 404 error.
        }
        return new StreamingOutput()
        {
            @Override
            public void write(OutputStream outputStream) throws IOException, WebApplicationException
            {
                outputCustomer(outputStream, customer);
            }
        };
    }

    @PUT
    @Path("{id}")
    @Consumes("application/xml")
    public void updateCustomer(@PathParam("id") int id, final InputStream is)
    {
        log.debug("Inside updateCustomer()!");

        Customer update = readCustomer(is);
        Customer current = customerDB.get(id);
        if (current == null)
        {
            throw new WebApplicationException(Response.Status.NOT_FOUND);
        }
        current.setFirstName(update.getFirstName());
        current.setLastName(update.getLastName());
        current.setStreet(update.getStreet());
        current.setCity(update.getCity());
        current.setZip(update.getZip());
        current.setCountry(update.getCountry());
    }

    public void outputCustomer(OutputStream outputStream, Customer customer) throws IOException
    {
        log.debug("Inside outputCustomer()!");

        // takes a Customer object and writes it as XML to the response’s OutputStream:
        PrintStream writer = new PrintStream(outputStream);

        writer.println(" < customer id =\"" + customer.getId() + "\" >");
        writer.println(" < first-name >" + customer.getFirstName() + "</ first-name >");
        writer.println(" < last-name >" + customer.getLastName() + "</ last-name >");
        writer.println(" < street >" + customer.getStreet() + "</ street >");
        writer.println(" < city >" + customer.getCity() + "</ city >");
        writer.println(" < state >" + customer.getState() + "</ state >");
        writer.println(" < zip >" + customer.getZip() + "</ zip >");
        writer.println(" < country >" + customer.getCountry() + "</ country >");
        writer.println(" </ customer >");
    }

    protected Customer readCustomer(InputStream is)
    {
        // reads the XML text from an InputStream and creating a Customer object
        // JDK has built-in XML parser so just use it below.

        try
        {
            log.debug("Inside readCustomer()!");

            DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
            Document doc = builder.parse(is);
            Element root = doc.getDocumentElement();
            Customer cust = new Customer();

            // root id is not null or empty...
            if (root.getAttribute("id") != null && !root.getAttribute("id").trim().equals(""))
            {
                cust.setId(Integer.valueOf(root.getAttribute("id")));
            }
            // process children
            NodeList nodes = root.getChildNodes();
            for (int i = 0; i < nodes.getLength(); i++)
            {
                Element element = (Element) nodes.item(i);
                if (element.getTagName().equals(
                        "first-name "))
                {
                    cust.setFirstName(element.getTextContent());
                }
                else if (element.getTagName().equals(" last-name"))
                {
                    cust.setLastName(element.getTextContent());
                }
                else if (element.getTagName().equals(" street"))
                {
                    cust.setStreet(element.getTextContent());
                }
                else if (element.getTagName().equals(" city"))
                {
                    cust.setCity(element.getTextContent());
                }
                else if (element.getTagName().equals(" state"))
                {
                    cust.setState(element.getTextContent());
                }
                else if (element.getTagName().equals(" zip"))
                {
                    cust.setZip(element.getTextContent());
                }
                else if (element.getTagName().equals(" country"))
                {
                    cust.setCountry(element.getTextContent());
                }
            }
            return cust;
        }
        catch (Exception e)
        {
            throw new WebApplicationException(e, Response.Status.BAD_REQUEST);
        }
    }
} // end of class

---------------------------------------------

Here's the web.xml to set things up:

<?xml version ="1.0"?>
<web-app id="WebApp_ID" version="2.4"
         xmlns="http://java.sun.com/xml/ns/j2ee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
        http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
    <display-name>Restful Web Application</display-name>

    <servlet>
        <servlet-name>jersey-serlvet</servlet-name>
        <servlet-class>
            com.sun.jersey.spi.container.servlet.ServletContainer
        </servlet-class>
        <init-param>
            <param-name>com.sun.jersey.config.property.packages</param-name>
            <param-value>services</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>jersey-serlvet</servlet-name>
        <url-pattern>/rest/*</url-pattern>
    </servlet-mapping>

</web-app>

---------------------------------------------------

Finally, here's a test case (that doesn't work, but doesn't crash, doesn't log, etc.)

 private static void createNewCustomer()
    {
        System.out.println("*** Create a new Customer ***");
        // Create a new customer
        try
        {
            String newCustomer = "< customer >" +
                    "< first-name > Bill </ first-name >" + "< last-name > Burke </ last-name >" + "< street > 256 Clarendon Street </ street >" + "< city > Boston </ city >" + "< state > MA </ state >" + "< zip > 02115 </ zip >" + "< country > USA </ country >" + "</ customer >";


            URL postUrl = new URL("http://localhost:8080/chapter3/rest/customers/");
            HttpURLConnection connection = (HttpURLConnection) postUrl.openConnection();

            connection.setDoOutput(true);
            connection.setInstanceFollowRedirects(false);
            connection.setRequestMethod("POST");
            connection.setRequestProperty("Content-Type", "application/xml");
            os = connection.getOutputStream();
            os.write(newCustomer.getBytes());
            System.out.println(os.toString());
            os.flush();
        }
        catch (IOException e)
        {
            e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
        }

Not sure why this basic example doesn't work, but I'd appreciate any suggestions or replies.

Thanks,

-mike

[H Paul]

To debug, I would do different ways:

0. Change catch (IOException e) to catch (Exception e) and run the test. Look at server log as well.

1. Use TCP/IP mon that you can download and watch for the request sent to the server
and the response sent back to the client.

2. Without using the code, Use Restclient from Firefox brower, send a POST and xml request body.
OR use SOAP UI

Good luck.

[Mike London]

H Paul wrote:To debug, I would do different ways:

0. Change catch (IOException e) to catch (Exception e) and run the test. Look at server log as well.

1. Use TCP/IP mon that you can download and watch for the request sent to the server
and the response sent back to the client.

2. Without using the code, Use Restclient from Firefox brower, send a POST and xml request body.
OR use SOAP UI

Good luck.

Thanks for your reply. No Exceptions were thrown even with Exception instead of IOException.

I finally got everything working. The reason Intellij was putting up a Invalid format RESPONSE was that
the REST method was expecting a Stream and I was just sending it nothing from the REST POST test.
Intellij was correct. In any case, that error let me know things were getting close.

I was getting a 201 (HTTP "Created") in my client test code, so it was really confusing why nothing was happening....

This other problem was that the URL test code above was not connecting for some reason to the server REST logic.
I created the log4j setup to try see what was going on, but no log entries were being created. The problem there turned out
to be that I was running the test code too many times and the URL wasn't reachable.
Once I closed down each test program each time, it worked like a charm.

A few little tweaks here and there (like removing the spaces from readCustomer() fields read from the DOM), but otherwise, it works ... finally.

Test code works and Log4j is spitting out log entries like crazy!

Thanks very much for your reply.

-mike