GWT - Basic

Concepts Understand the architecture and principles that drive GWT.

• Describe the mechanism of the GWT compiler process
• Explain what benefits can be expected from using Java as a programming language (as opposed to Javascript programming)
• Describe how cross-browser compatibility is handled
• Understand the role of each component of GWT:
  • GWT Java-to-JavaScript Compiler
  • GWT Hosted Web Browser
  • JRE emulation library
  • GWT Web UI class library

Java language support Understand the subset of Java that is supported by GWT

• Identify what level of Java language is supported
• Describe the caveats that are due to the target language (Javascript), in particular:
  • primitive types (range, wrapping, float vs double)
  • long emulation
  • absence of multithreading
  • limited reflection possibilities
• List what packages/classes of the standard Java library are emulated

Hosted mode vs web mode

• Describe the purpose of hosted mode
• Compare and contrast running native Java bytecode with hosted mode vs translated JavaScript in web mode
• Discuss the differences between the hosted mode browser and a standard browser
• Explain how hosted mode is used to debug an application
• Explain how to switch to web mode from the hosted mode browser
• Discuss why and when to use web mode

Package and file structure

• Discuss the differences between translatable (client-side) code, non-translatable (server-side) code, and static files
• Describe the standard directory and package layout

HTML host page and entry point

• Describe hat a GWT entry point is
• Wirte a Java class that implements a GWT entry point
• Explain the relationship between GWT code and the HTML host page
• Write a GWT-enabled HTML host page

Module configuration file

• Describe the purpose of the GWT module file
• Explain how it is named and where to look for it
• Write a minimal module file with the following settings:
  • inherited modules
  • starting point
  • stylesheet

Basic UI building

• Compare and contrast GWT UI programming with other GUI technologies such as Swing
• Discuss the differences between a simple widget and a panel
• Describe the most basic widgets (Button, TextBox)
• Write code that creates a Button and attaches a ClicHandler to it
• Describe the most common panels (HorizontalPanel, VerticalPanel, TabPanel)
• Write code that creates a simple widget and adds it to a panel
• Explain what a RootPanel is
• Write code that obtains the default RootPanel / the RootPanel associated to a HTML element designated by it ID

GWT RPC

• Describe the principles of GWT RPC
• Explain how the asynchronous nature of RPC affects remote calls
• Write minimal classes/interfaces to implement a GWT RPC service with a single method:
  • the service interface
  • the service async interface
  • the service implementation
• Write code that performs the steps required to make an actual RPC call:
  • obtain the local proxy
  • define a callback
  • call the proxy
• Discuss the concept of serializability and its GWT variant
• Make a class serializable
• Modify a GWT module configuration file to activate the embedded application server for testing a GWT RPC service