GWT

The google web toolkit Stefaan Ternier

Classic web application model (synchronous)

Ajax web application model (asynchronous)

Asynchronous JavaScript and XML (AJAX) Server - side Client – side Javascript -> Firefox/IE <html> [...] <script type="text/javascript"> [...] xmlhttp.open("POST", url, true); xmlhttp.onreadystatechange = function(func) { if (xmlhttp.readyState == 4) { [...] } } xmlhttp.setRequestHeader('MessageType', 'CALL'); xmlhttp.setRequestHeader('Content-Type', 'text/xml'); </script> <body>[...]</body> </html> JAVA -> Tomcat package com.mycompany.server; import com.google.gwt.user.server.rpc.RemoteServiceServlet; import com.mycompany.client.MyAddService; public class MyAddServiceImpl extends RemoteServiceServlet implements MyAddService{ public int add(int a, int b) { return a + b; } }

Asynchronous JavaScript and XML (AJAX) Server - side Client – side Javascript JAVA + no page transition, no blocking No IDE Debugging is difficult weakly typed + eclipse: debugging, easy development good IDE’s Debugging is easy strongly typed

Google Web Toolkit (GWT) @ deployment time @ development time <html> [...] <script type="text/javascript"> [...] xmlhttp.open("POST", url, true); xmlhttp.onreadystatechange = function(func) { if (xmlhttp.readyState == 4) { [...] } } xmlhttp.setRequestHeader('MessageType', 'CALL'); xmlhttp.setRequestHeader('Content-Type', 'text/xml'); </script> <body>[...]</body> </html> JAVA/eclipse javascript Hosted mode JVM IDE Compile to JAVA bytecode Compile to Javascript

GWT: create project in eclipse projectCreator -eclipse MySumationProject applicationCreator -eclipse MySumationProject com.mycompany.client.MySumApplication Import project into eclipse

GWT: Build your first app GWT JAVA Code HTML Host page

GWT: Build your first app final Label resultaatLabel = new Label(); final TextBox aBox= new TextBox(); final TextBox bBox= new TextBox(); final Button button = new Button("Click me"); button.addClickListener( new ClickListener() { public void onClick(Widget sender) { resultaatLabel.setText("hier komt het resultaat"); } }); RootPanel. get ("inputboxa").add(aBox); RootPanel. get ("inputboxb").add(bBox); RootPanel. get ("resultaat").add(resultaatLabel); RootPanel. get ("bereken").add(button); GWT Widgets Bind to HTML page

GWT: project structure Client-side source files and subpackages com/mycompany/client/ The project root package contains module XML files com/mycompany/ Server-side code and subpackages com/mycompany/server/ Static resources that can be served publicly com/mycompany/public/ Purpose Package

GWT: module XML files Defines configuration of GWT modules Source entry point HTML page entry Extension: .gwt.xml Example: <module>  <inherits name='com.google.gwt.user.User'/>  <entry-point class='com.mycompany.client.MyApplication'/> </module>

GWT: module example com/mycompany/public/MyApplication.html com/mycompany/MyApplication.gwt.xml com/mycompany/client/MyApplication.java

GWT Widgets SuggestBox TabBar Panel More… http:// code.google.com / webtoolkit / documentation / com.google.gwt.doc.DeveloperGuide.UserInterface.html

Google Maps public void onModuleLoad() { GMap2Widget mapWidget = new GMap2Widget("300", "400"); final GMap2 gmaps = mapWidget.getGmap(); RootPanel.get("slot1").add(mapWidget); } <module> <inherits name='com.google.gwt.user.User'/> <inherits name='com.mapitz.gwt.googleMaps.GoogleMaps' /> <entry-point class='com.mycompany.client.MyMapsApplication'/> </module> Module XML JAVA code

Google Maps - Geocoder Convert addresses to latitude/longitude pairs

RPC plumbing diagram package com.mycompany.client; import com.google.gwt.user.client.rpc.RemoteService; public interface MyAddService extends RemoteService { public int add(int a, int b); }

RPC plumbing diagram package com.mycompany.server; import com.google.gwt.user.server.rpc.RemoteServiceServlet; import com.mycompany.client.MyAddService; public class MyAddServiceImpl extends RemoteServiceServlet implements MyAddService{ public int add(int a, int b) { int z = a + b; return z; } }

RPC plumbing diagram package com.mycompany.client; import com.google.gwt.user.client.rpc.AsyncCallback; public interface MyAddServiceAsync { public void add(int a, int b, AsyncCallback callback); }

Deploy service Tomcat -> add Servlet Hosted mode -> modify module XML <module> <inherits name='com.google.gwt.user.User'/> <entry-point class='com.mycompany.client.MyApplication'/> <servlet path="/addService" class="com.mycompany.server.MyAddServiceImpl“/> </module>

Actually making a call button.addClickListener( new ClickListener() { public void onClick(Widget sender) { MyAddServiceAsync addService = (MyAddServiceAsync) GWT.create(MyAddService.class); ServiceDefTarget endpoint = (ServiceDefTarget) addService; String moduleRelativeURL = GWT.getModuleBaseURL() + "addService“; endpoint.setServiceEntryPoint(moduleRelativeURL); AsyncCallback callback = new AsyncCallback(){ public void onSuccess(Object result){ resultaatLabel.setText(result.toString()); } public void onFailure(Throwable caught) { resultaatLabel.setText(caught.getMessage()); } }; addService.add(Integer.parseInt(aBox.getText()), Integer.parseInt(bBox.getText()), callback); } } );

References Google Web Toolkit, http://code.google.com/webtoolkit/ W3 Schools, http://www.w3schools.com/ Apache axis, http://ws.apache.org/axis/ GWT – Google Maps API http://sourceforge.net/projects/gwt/ http://www.adaptivepath.com/ideas/essays/archives/000385.php

Computerklas /localhost/packages/gwt/gwt-linux-1.4.60 projectCreator applicationCreator /localhost/packages/gwt/googlemaps Lib javadoc_2_2_1

GWT

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