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GWT servlet works fine in Eclipse, fails to be reached in tomcat and virgo tomcat

Greenhorn

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posted 12 years ago

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I worked on a GWT web application with client, shared and server code. It all works great in Eclipse when Run As or Debug As a web application, the servlet is found just fine. But if I deploy it in Virgo Tomcat or just Tomcat the calls to the servlet don't work. I get a 404. I have searched and many similar postings are around but none of them fixed my issue. Error from my app, not the vanilla greet example but it is the same:

getSituation failed: 404 <html><head><title>Apache Tomcat/7.0.26 - Error report</title><style></style> </head><body><h1>HTTP Status 404 - Servlet SituationServlet is not available</h1><HR size="1" noshade="noshade">type Status reportmessage Servlet SituationServlet is not availabledescription The requested resource (Servlet SituationServlet is not available) is not available.<HR size="1" noshade="noshade"><h3>Apache Tomcat/7.0.26</h3></body></html>

I thought maybe it was something I had done so I then created the standard GWT web application example with the greetServer. I added a Warbuilder.xml file to build the war file. It has exactly the same problem so I am wondering what on earth I have done or not done.

Could it be my warbuilder? That's the only part that isn't in the standard GWT web application sample:
<project name="VisualNovel2" basedir="." default="default">

<target name="default" depends="buildwar,deploy"></target>

<target name="buildwar">
<war basedir="war" destfile="VisualNovel2.war" webxml="war/WEB-INF/web.xml">
<exclude name="WEB-INF/**" />
<webinf dir="war/WEB-INF/">
<include name="**/*.jar" />
</webinf>
</war>
</target>

<target name="deploy">
<copy file="VisualNovel2.war" todir="." />
</target>

</project>

Here is the web.xml:

Here is the VisualNovel2.gwt.xml file:
<?xml version="1.0" encoding="UTF-8"?>
<module rename-to='visualnovel2'>

<inherits name='com.google.gwt.user.User'/>




<inherits name='com.google.gwt.user.theme.clean.Clean'/>







<entry-point class='visualnovel2.client.VisualNovel2'/>


<source path='client'/>
<source path='shared'/>

</module>

GreetingService.java:

GreetingServiceAsync.java:

VisualNovel2.java:

package visualnovel2.client;

import visualnovel2.shared.FieldVerifier;
import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.core.client.GWT;
import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.event.dom.client.KeyCodes;
import com.google.gwt.event.dom.client.KeyUpEvent;
import com.google.gwt.event.dom.client.KeyUpHandler;
import com.google.gwt.user.client.rpc.AsyncCallback;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.DialogBox;
import com.google.gwt.user.client.ui.HTML;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.TextBox;
import com.google.gwt.user.client.ui.VerticalPanel;

/**
 * Entry point classes define <code>onModuleLoad()</code>.
 */
public class VisualNovel2 implements EntryPoint {
	/**
	 * The message displayed to the user when the server cannot be reached or
	 * returns an error.
	 */
	private static final String SERVER_ERROR = "An error occurred while "
			+ "attempting to contact the server. Please check your network "
			+ "connection and try again.";

/**
	 * Create a remote service proxy to talk to the server-side Greeting service.
	 */
	private final GreetingServiceAsync greetingService = GWT
			.create(GreetingService.class);

/**
	 * This is the entry point method.
	 */
	public void onModuleLoad() {
		final Button sendButton = new Button("Send");
		final TextBox nameField = new TextBox();
		nameField.setText("GWT User");
		final Label errorLabel = new Label();

// We can add style names to widgets
		sendButton.addStyleName("sendButton");

// Add the nameField and sendButton to the RootPanel
		// Use RootPanel.get() to get the entire body element
		RootPanel.get("nameFieldContainer").add(nameField);
		RootPanel.get("sendButtonContainer").add(sendButton);
		RootPanel.get("errorLabelContainer").add(errorLabel);

// Focus the cursor on the name field when the app loads
		nameField.setFocus(true);
		nameField.selectAll();

// Create the popup dialog box
		final DialogBox dialogBox = new DialogBox();
		dialogBox.setText("Remote Procedure Call");
		dialogBox.setAnimationEnabled(true);
		final Button closeButton = new Button("Close");
		// We can set the id of a widget by accessing its Element
		closeButton.getElement().setId("closeButton");
		final Label textToServerLabel = new Label();
		final HTML serverResponseLabel = new HTML();
		VerticalPanel dialogVPanel = new VerticalPanel();
		dialogVPanel.addStyleName("dialogVPanel");
		dialogVPanel.add(new HTML("Sending name to the server:"));
		dialogVPanel.add(textToServerLabel);
		dialogVPanel.add(new HTML(" Server replies:"));
		dialogVPanel.add(serverResponseLabel);
		dialogVPanel.setHorizontalAlignment(VerticalPanel.ALIGN_RIGHT);
		dialogVPanel.add(closeButton);
		dialogBox.setWidget(dialogVPanel);

// Add a handler to close the DialogBox
		closeButton.addClickHandler(new ClickHandler() {
			public void onClick(ClickEvent event) {
				dialogBox.hide();
				sendButton.setEnabled(true);
				sendButton.setFocus(true);
			}
		});

// Create a handler for the sendButton and nameField
		class MyHandler implements ClickHandler, KeyUpHandler {
			/**
			 * Fired when the user clicks on the sendButton.
			 */
			public void onClick(ClickEvent event) {
				sendNameToServer();
			}

/**
			 * Fired when the user types in the nameField.
			 */
			public void onKeyUp(KeyUpEvent event) {
				if (event.getNativeKeyCode() == KeyCodes.KEY_ENTER) {
					sendNameToServer();
				}
			}

/**
			 * Send the name from the nameField to the server and wait for a response.
			 */
			private void sendNameToServer() {
				// First, we validate the input.
				errorLabel.setText("");
				String textToServer = nameField.getText();
				if (!FieldVerifier.isValidName(textToServer)) {
					errorLabel.setText("Please enter at least four characters");
					return;
				}

// Then, we send the input to the server.
				sendButton.setEnabled(false);
				textToServerLabel.setText(textToServer);
				serverResponseLabel.setText("");
				greetingService.greetServer(textToServer,
						new AsyncCallback<String>() {
							public void onFailure(Throwable caught) {
								// Show the RPC error message to the user
								dialogBox
										.setText("Remote Procedure Call - Failure");
								serverResponseLabel
										.addStyleName("serverResponseLabelError");
								serverResponseLabel.setHTML(SERVER_ERROR);
								dialogBox.center();
								closeButton.setFocus(true);
							}

public void onSuccess(String result) {
								dialogBox.setText("Remote Procedure Call");
								serverResponseLabel
										.removeStyleName("serverResponseLabelError");
								serverResponseLabel.setHTML(result);
								dialogBox.center();
								closeButton.setFocus(true);
							}
						});
			}
		}

// Add a handler to send the name to the server
		MyHandler handler = new MyHandler();
		sendButton.addClickHandler(handler);
		nameField.addKeyUpHandler(handler);
	}
}

GreetingServiceImpl.java:

package visualnovel2.server;

import visualnovel2.client.GreetingService;
import visualnovel2.shared.FieldVerifier;
import com.google.gwt.user.server.rpc.RemoteServiceServlet;

/**
 * The server side implementation of the RPC service.
 */
@SuppressWarnings("serial")
public class GreetingServiceImpl extends RemoteServiceServlet implements
		GreetingService {

public String greetServer(String input) throws IllegalArgumentException {
		// Verify that the input is valid. 
		if (!FieldVerifier.isValidName(input)) {
			// If the input is not valid, throw an IllegalArgumentException back to
			// the client.
			throw new IllegalArgumentException(
					"Name must be at least 4 characters long");
		}

String serverInfo = getServletContext().getServerInfo();
		String userAgent = getThreadLocalRequest().getHeader("User-Agent");

// Escape data from the client to avoid cross-site script vulnerabilities.
		input = escapeHtml(input);
		userAgent = escapeHtml(userAgent);

return "Hello, " + input + "! I am running " + serverInfo
				+ ". It looks like you are using: " + userAgent;
	}

/**
	 * Escape an html string. Escaping data received from the client helps to
	 * prevent cross-site script vulnerabilities.
	 * 
	 * @param html the html string to escape
	 * @return the escaped string
	 */
	private String escapeHtml(String html) {
		if (html == null) {
			return null;
		}
		return html.replaceAll("&", "&").replaceAll("<", "<")
				.replaceAll(">", ">");
	}
}

Shared FieldVerifier.java:

package visualnovel2.shared;

/**
 * 
 * FieldVerifier validates that the name the user enters is valid.
 * 
 * 
 * This class is in the <code>shared</code> package because we use it in both
 * the client code and on the server. On the client, we verify that the name is
 * valid before sending an RPC request so the user doesn't have to wait for a
 * network round trip to get feedback. On the server, we verify that the name is
 * correct to ensure that the input is correct regardless of where the RPC
 * originates.
 * 
 * 
 * When creating a class that is used on both the client and the server, be sure
 * that all code is translatable and does not use native JavaScript. Code that
 * is not translatable (such as code that interacts with a database or the file
 * system) cannot be compiled into client side JavaScript. Code that uses native
 * JavaScript (such as Widgets) cannot be run on the server.
 * 
 */
public class FieldVerifier {

/**
	 * Verifies that the specified name is valid for our service.
	 * 
	 * In this example, we only require that the name is at least four
	 * characters. In your application, you can use more complex checks to ensure
	 * that usernames, passwords, email addresses, URLs, and other fields have the
	 * proper syntax.
	 * 
	 * @param name the name to validate
	 * @return true if valid, false if invalid
	 */
	public static boolean isValidName(String name) {
		if (name == null) {
			return false;
		}
		return name.length() > 3;
	}
}

My own code is more complex but there is no need to include it as it has the same issue, can't talk to the servlet. It works perfectly from within Eclipse and annoyingly on my Windows 7 64 system with Virgo Tomcat 3.5 and a 64-bit Linux system with Virgo Tomcat 3.5 or Tomcat 6 the system can't connect to the servlet.

I have other services which do work which makes me think it is not a config issue on virgo tomcat or tomcat but if there is config I can fix, please let me know. They are more complicated so I didn't want to use them, I thought I could just use GWT but obviously I am missing something.

Thanks in advance for any help you can provide. It is probably a stupid one liner or something that I've forgotten but for the life of me I cannot find it...

If you want to replicate this simply open eclipse (I have Juno with JDK 1.7.0_07) and create a new Google Web Application Project, create a Warbuilder.xml file, run Google->compile, do Run As ant builder on the Warbuilder.xml and drop the war file in your virgo tomcat pickup or tomcat webapps directory.

Harry

Harry Pulley

Greenhorn

Posts: 2

posted 12 years ago

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Local help showed me that my class files weren't in the .war file, duh. Adding the class files to the warbuilder.xml to put them in the war file lets tomcat successfully deploy and run the servlet.

It's a pleasure to see superheros taking such an interest in science. And this tiny ad:

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