Question

I’m building a login application.I’m getting Umbrella Exception everytime, after clicking the Button….unable to find the root cause. Im providing the code and the error list. Please provide me with the fix. Using GWT-RPC

---

CLIENT SIDE
1. VinLog.java

package com.login.vinayak.client;

import com.google.gwt.core.client.EntryPoint;

public class VinLog implements EntryPoint {
    private GreetingServiceAsync GreetingService = (GreetingServiceAsync) GWT.create(GreetingService.class);
    public void onModuleLoad() {
        GWT.setUncaughtExceptionHandler(new UncaughtExceptionHandler() {
            public void onUncaughtException(Throwable e) {
              Window.alert("uncaught: " +e.getMessage());
              Window.alert("uncaught: " + e.getMessage());
              String s = buildStackTrace(e, "RuntimeExceotion:\n");
              Window.alert(s);
              e.printStackTrace();
              System.out.println(e.getCause());
            }
        });
        RootPanel rootPanel = RootPanel.get();

        SimplePanel simplePanel = new SimplePanel();
        rootPanel.add(simplePanel, 0, 0);
        simplePanel.setSize("450px", "19px");

        Label lblLoginForm = new Label("LOGIN");
        lblLoginForm.setHorizontalAlignment(HasHorizontalAlignment.ALIGN_CENTER);
        simplePanel.setWidget(lblLoginForm);
        lblLoginForm.setSize("544px", "41px");

        Label lblUserName = new Label("User Name");
        rootPanel.add(lblUserName, 10, 124);

        Label lblPassword = new Label("Password");
        rootPanel.add(lblPassword, 10, 183);

        final TextBox textBox = new TextBox();
        textBox.setAlignment(TextAlignment.CENTER);
        rootPanel.add(textBox, 112, 114);
        textBox.setSize("139px", "18px");

        final PasswordTextBox passwordTextBox = new PasswordTextBox();
        rootPanel.add(passwordTextBox, 112, 173);
        passwordTextBox.setSize("139px", "18px");

        Button btnClickToEnter = new Button("Click to Enter");
        btnClickToEnter.addClickHandler(new ClickHandler() {
            public void onClick(ClickEvent event) {
                String j=textBox.getText();
                String k=passwordTextBox.getText();
                GreetingService.loginuser(j, k, new AsyncCallback<String>() {
                    public void onFailure(Throwable caught) {
                        Window.alert("welcome");
                        }
                    public void onSuccess(String result) {
                        Window.alert("try again");
                    }
                 });
            }
    });
        rootPanel.add(btnClickToEnter, 10, 229);

        final ListBox comboBox = new ListBox();
        comboBox.addChangeHandler(new ChangeHandler() {
            public void onChange(ChangeEvent event) {
                Object ob=comboBox.getElement(); 
                if(ob=="Guest") {
                    Window.alert("Username and Passowrd is: Guest007");
                }
            }               
        });
        comboBox.addItem("User");
        comboBox.addItem("Admin");
        comboBox.addItem("Guest");
        rootPanel.add(comboBox, 10, 51);
        comboBox.setSize("85px", "22px");

        Image image = new Image("home.gif");
        rootPanel.add(image, 310, 98);
        image.setSize("182px", "155px");
    }
    protected String buildStackTrace(Throwable t, String log) {
            if (t != null) {
                log += t.getClass().toString();
                log += t.getMessage(); 
                StackTraceElement[] stackTrace = t.getStackTrace();
                if (stackTrace != null) {
                  StringBuffer trace = new StringBuffer();

                  for (int i = 0; i < stackTrace.length; i++) {
                    trace.append(stackTrace[i].getClassName() + "." + stackTrace[i].getMethodName() + "("
                        + stackTrace[i].getFileName() + ":" + stackTrace[i].getLineNumber());
                  }
                  log += trace.toString();
                }
                Throwable cause = t.getCause();
                if (cause != null && cause != t) {
                  log += buildStackTrace(cause, "CausedBy:\n");
                }
              }
            return log;
    }
}

2.GreetingService.java

package com.login.vinayak.client;

import com.google.gwt.user.client.rpc.RemoteService;
import com.google.gwt.user.client.rpc.RemoteServiceRelativePath;

@SuppressWarnings("unused")
public interface GreetingService extends RemoteService {
    public String loginuser(String username, String password);
}

3.GreetinServiceAsync.java

package com.login.vinayak.client;

import com.google.gwt.user.client.rpc.AsyncCallback;

public interface GreetingServiceAsync {
    public void loginuser(String username, String password, AsyncCallback<String> callback);
}

---

SERVER SIDE ==> GreetingServiceImpl.java

package com.login.vinayak.server;

import com.login.vinayak.client.GreetingService;
import com.google.gwt.user.server.rpc.RemoteServiceServlet;
import java.sql.DriverManager;
import java.sql.ResultSet;
import com.google.gwt.dev.generator.ast.Statement;

public class GreetingServiceImpl extends RemoteServiceServlet implements GreetingService{
    private static final long serialVersionUID = 1L;

    public String loginuser(String username,String password) {
        try {
            java.sql.Connection con = null;
            Class.forName("org.hsqldb.jdbcDriver");
            con = DriverManager.getConnection("jdbc:hsqldb:hsql://localhost/", "SA", "");
            Statement st=(Statement) con.createStatement();
            ResultSet rs=((java.sql.Statement) st).executeQuery("select username,password from lgfrm");
            String user=rs.getString(1);
            String pass=rs.getString(2);
            boolean b1=username.equals(user);
            boolean b2= password.equals(pass);
            if(b1==b2==true) {
            return "success";
            }
            }
    catch (Exception ae) {}
        return "Success";
    }
}

---

web.xml

> <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE web-app  PUBLIC
> "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
>   "http://java.sun.com/dtd/web-app_2_3.dtd">
> 
> <web-app> <servlet>
>       <servlet-name>GreetingServiceImpl</servlet-name>
>       <servlet-class>com.login.vinayak.server.GreetingServiceImpl</servlet-class>
> </servlet>    <servlet-mapping>
>       <servlet-name>GreetingServiceImpl</servlet-name>
>       <url-pattern>/Login</url-pattern>    </servlet-mapping>     <!-- Default page to serve -->  <welcome-file-list>
>       <welcome-file>VinLog.html</welcome-file>    </welcome-file-list>
> 
> </web-app>

---

ERROR LIST

com.google.gwt.event.shared.UmbrellaException: One or more exceptions
caught, see full set in UmbrellaException#getCauses at
com.google.gwt.event.shared.HandlerManager.fireEvent(HandlerManager.java:129)
at com.google.gwt.user.client.ui.Widget.fireEvent(Widget.java:129)
at
com.google.gwt.event.dom.client.DomEvent.fireNativeEvent(DomEvent.java:116)
at
com.google.gwt.user.client.ui.Widget.onBrowserEvent(Widget.java:177)
at com.google.gwt.user.client.DOM.dispatchEventImpl(DOM.java:1351)
at com.google.gwt.user.client.DOM.dispatchEvent(DOM.java:1307) at
sun.reflect.GeneratedMethodAccessor33.invoke(Unknown Source) at
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at
java.lang.reflect.Method.invoke(Unknown Source) at
com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
at
com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
at
com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
at
com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:337)
at
com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:218)
at
com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136)
at
com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561)
at
com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:269)
at
com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91)
at com.google.gwt.core.client.impl.Impl.apply(Impl.java) at
com.google.gwt.core.client.impl.Impl.entry0(Impl.java:213) at
sun.reflect.GeneratedMethodAccessor31.invoke(Unknown Source) at
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at
java.lang.reflect.Method.invoke(Unknown Source) at
com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
at
com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
at
com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)

**********ADDITIONAL ERROR-CAUSE LIST**********

Caused by:
com.google.gwt.user.client.rpc.ServiceDefTarget$NoServiceEntryPointSpecifiedException:
Service implementation URL not specified at
com.google.gwt.user.client.rpc.impl.RemoteServiceProxy.doPrepareRequestBuilderImpl(RemoteServiceProxy.java:430)
at
com.google.gwt.user.client.rpc.impl.RemoteServiceProxy.doInvoke(RemoteServiceProxy.java:368)
at
com.google.gwt.user.client.rpc.impl.RemoteServiceProxy$ServiceHelper.finish(RemoteServiceProxy.java:74)
at
com.login.vinayak.client.GreetingService_Proxy.loginuser(GreetingService_Proxy.java:34)
at com.login.vinayak.client.VinLog$2.onClick(VinLog.java:82) at
com.google.gwt.event.dom.client.ClickEvent.dispatch(ClickEvent.java:54)
at
com.google.gwt.event.dom.client.ClickEvent.dispatch(ClickEvent.java:1)
at com.google.gwt.event.shared.GwtEvent.dispatch(GwtEvent.java:1) at
com.google.web.bindery.event.shared.EventBus.dispatchEvent(EventBus.java:40)
at
com.google.web.bindery.event.shared.SimpleEventBus.doFire(SimpleEventBus.java:193)
at
com.google.web.bindery.event.shared.SimpleEventBus.fireEvent(SimpleEventBus.java:88)
at
com.google.gwt.event.shared.HandlerManager.fireEvent(HandlerManager.java:127)

---

KINDLY PROVIDE ME WITH THE FIX…TY

Answer 1

…And there you have it: Service implementation URL not specified...

You need to somehow tell GWT where on the backend the RPC call should go. You may do that with the annotation @RemoteServiceRelativePath on the service interface or programmatically on the ServiceDefTarget instance (which is effectively your async service instance).

Cheers,