What is Theme module in GWT?

Module	Logical Name	Module Definition	Contents
Chrome	com.google.gwt.user.theme.chrome.Chrome	Chrome.gwt.xml	Style sheet and images for the Chrome theme.
Dark	com.google.gwt.user.theme.dark.Dark	Dark.gwt.xml	Style sheet and images for the Dark theme.
Standard	com.google.gwt.user.theme.standard.Standard	Standard.gwt.xml	Style sheet and images for the Standard theme.

GWT also provides several theme modules which contain default styles for widgets and panels. You can specify one theme in your project's module XML file to use as a starting point for styling your application, but you are not required to use any of them.

Deffered Binding in GWT

Deffered Binding :-Compile time create many version. and load on version according to version.

Deferred Binding Using Replacement
    <module>

      <!--  ... other configuration omitted ... -->

      <!-- Fall through to this rule is the browser isn't IE or Mozilla -->
      <replace-with class="com.google.gwt.user.client.ui.impl.PopupImpl">
        <when-type-is class="com.google.gwt.user.client.ui.impl.PopupImpl"/>
      </replace-with>

      <!-- Mozilla needs a different implementation due to issue #410 -->
      <replace-with class="com.google.gwt.user.client.ui.impl.PopupImplMozilla">
        <when-type-is class="com.google.gwt.user.client.ui.impl.PopupImpl" />
        <any>
          <when-property-is name="user.agent" value="gecko"/>
          <when-property-is name="user.agent" value="gecko1_8" />
        </any>
      </replace-with>

      <!-- IE has a completely different popup implementation -->
      <replace-with class="com.google.gwt.user.client.ui.impl.PopupImplIE6">
        <when-type-is class="com.google.gwt.user.client.ui.impl.PopupImpl"/>
        <when-property-is name="user.agent" value="ie6" />
      </replace-with>
    </module>
   
    Deferred binding using Genrator

What is standard module in GWT?

Standard Modules GWT 1.5

Module	Logical Name	Module  Definition	Contents
User	com.google.gwt.user.User	User.gwt.xml	Core GWT functionality
HTTP	com.google.gwt.http.HTTP	HTTP.gwt.xml	Low-level HTTP communications library
JSON	com.google.gwt.json.JSON	JSON.gwt.xml	JSON creation and parsing
JUnit	com.google.gwt.junit.JUnit	JUnit.gwt.xml	JUnit testing framework integration
XML	com.google.gwt.xml.XML	XML.gwt.xml	XML document creation and parsing

Generally, you want to inherit at least the User module. The User module contains all the core GWT functionality, including the EntryPoint class. The User module also contains reusable UI components (widgets and panels) and support for the History feature, Internationalization, DOM programming, and more.


User.gwt.xml
<module>
   <inherits name="com.google.gwt.animation.Animation"/>
   <inherits name="com.google.gwt.canvas.Canvas"/>
   <inherits name="com.google.gwt.core.Core"/>
   <inherits name="com.google.gwt.debug.DebugBase"/>
   <inherits name='com.google.gwt.dom.builder.DomBuilder'/>
   <inherits name="com.google.gwt.editor.Editor" />
   <inherits name="com.google.gwt.event.Event"/>
   <inherits name="com.google.gwt.geolocation.Geolocation" />
   <inherits name="com.google.gwt.i18n.I18N"/>
   <inherits name="com.google.gwt.layout.Layout"/>
   <inherits name="com.google.gwt.media.Media"/>
   <inherits name="com.google.gwt.resources.Resources"/>
   <inherits name="com.google.gwt.safecss.SafeCss" />
   <inherits name="com.google.gwt.safehtml.SafeHtml" />
   <inherits name="com.google.gwt.storage.Storage" />
   <inherits name="com.google.gwt.text.Text"/>
   <inherits name="com.google.gwt.touch.Touch"/>
   <inherits name="com.google.gwt.uibinder.UiBinder"/>
   <inherits name="com.google.gwt.user.AsyncProxy"/>
   <inherits name="com.google.gwt.user.CaptionPanel" />
   <inherits name="com.google.gwt.user.cellview.CellView"/>
   <inherits name="com.google.gwt.user.ClippedImage"/>
   <inherits name="com.google.gwt.user.datepicker.DatePicker"/>
   <inherits name="com.google.gwt.user.DocumentMode"/>
   <inherits name="com.google.gwt.user.DocumentRoot" />
   <inherits name="com.google.gwt.user.DOM"/>
   <inherits name="com.google.gwt.user.FileUpload"/>
   <inherits name="com.google.gwt.user.Focus"/>
   <inherits name="com.google.gwt.user.Form"/>
   <inherits name="com.google.gwt.user.History"/>
   <inherits name="com.google.gwt.user.HTTPRequest"/>
   <inherits name="com.google.gwt.user.Hyperlink"/>
   <inherits name="com.google.gwt.user.ImageBundle"/> 
   <inherits name="com.google.gwt.user.Popup"/>
   <inherits name="com.google.gwt.user.RemoteService"/>
   <inherits name="com.google.gwt.user.ResizeLayoutPanel"/>
   <inherits name="com.google.gwt.user.RichText"/>
   <inherits name="com.google.gwt.user.Scroll"/>
   <inherits name="com.google.gwt.user.SplitPanel"/>
   <inherits name="com.google.gwt.user.TextBox"/>
   <inherits name="com.google.gwt.user.Tree"/>
   <inherits name="com.google.gwt.user.Window" />
   <inherits name="com.google.gwt.widget.Widget"/>

   <super-source path="translatable"/>
   <source path="client"/>
</module>

What is logical name of a module?

For com.ashish.GWTExample.gwt.xml, logical name will bw com.ashish.GWTExample

What configuration we write in modulename.gwt.xml?

1. inherited modules 
2. entry point class
3. source path entry, public path entry
4. deferred binding rules, including property providers and class generators

<?xml version="1.0" encoding="UTF-8"?>
<module rename-to='gxtexample'>
  <!-- Inherit the core Web Toolkit stuff.                        -->
  <inherits name='com.google.gwt.user.User'/>

  <!-- Inherit the default GWT style sheet.  You can change       -->
  <!-- the theme of your GWT application by uncommenting          -->
  <!-- any one of the following lines.                            -->
  <inherits name='com.google.gwt.user.theme.clean.Clean'/>
  <!-- <inherits name='com.google.gwt.user.theme.standard.Standard'/> -->
  <!-- <inherits name='com.google.gwt.user.theme.chrome.Chrome'/> -->
  <!-- <inherits name='com.google.gwt.user.theme.dark.Dark'/>     -->

  <!-- Other module inherits                                      -->

  <!-- Specify the app entry point class.                         -->
  <entry-point class='com.gxt.client.GXTExample'/>
  <!-- Specify the paths for translatable code                    -->
  <source path='client'/>
  <source path='shared'/>

</module>

why we use module rename-to in modulename.gwt.xml?

in GWT application, logical name of module is large like com.ashish.gwtExample. If i have to use this name anywhere like in web.xml then it is complicated name. So we can short this name using rename-to like gwtExample.

<module rename-to='gxtexample'>
</module>

What source path we provide in modulename.gwt.xml? and why?

It is path for client and shared.
<source path='client'/>
  <source path='shared'/>


source path is used to tell GWT compiler that which package code, we need to convert into  javascript. We do not entry of server package becoz we do not convert it into javascript.

How many entry point can we define in modulename.gwt.xml?

Basically there is 1 entry point in modulename.gwt.xml but it can not be or can be more than 1.

If entry point is zero than blank page or html page will load.

If entry point is more than 1 then all entry point data will upload.

Advantages of GWT

1. Making a webpage is very easy.
2. Support for all browser.
3. We can use UI binding(XML=HTML+GWT)
4. External libraries like smartgwt, gxt etc.
5. Resources make application very effective.
6. Many images combined into single image so remove client server call.
7. Deffered binding make different version of an application and at page loading time we can load file according to browser so remove js code which we use for different browser.
8. Use of MVP.
9. Event are handled on one place.

GWT 2.3 vs 2.4

1. Scrolling in Datagrid with fixed header and footer.
2. UI Binder support, IsWidget support.
3. Fast speed in compile.