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YaJUG: What's new in GWT2


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What's new in GWT2

What's new in GWT2

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  • 1. GWT 2 = Easier AJAX
  • 2. Who am I?
    Olivier Gérardin
    Technical Director, Sfeir Benelux (groupe Sfeir)
    Java / Web architect
    13+ years Java
    3 years GWT
  • 3. Agenda
    GWT reminders
    New in GWT 2.0
    In-browser development mode
    Code splitting & compile report
    Client bundle
    Layout panels
    Pointers, Conclusion, Q&A
  • 4. Reminders
  • 5. GWT solves all your problems
    GWT gives you AJAX without the pain of JavaScript development
    Takes care of cross-browser issues
    Allows full debugging (breakpoints, step by step, inspecting/watching variables)
    Strong static typing early error detection
    Full refactoring options
    No browser plugin or mandatory IDE
    Short learning curve
    Simple RPC mechanism built in
    But can communicate with any server technology
  • 6. Program in Java…
    GWT allows developing client-side web apps in full Java (with only a few restrictions)
    Leverage existing Java tools and skills
    Use any IDE (Eclipse, NetBeans, IntelliJ, …)
    Program like a traditional graphical client (Swing, SWT, …)
    Widgets, containers, listeners, etc.
    Use OO patterns (MVC, MVP, observer, composite, etc.)
    Test like any Java app
    Use standard Java debuggers
    Test with JUnit
  • 7. … deploy in JavaScript
    JavaScript is only generated:
    For deployment
    To test in actual web mode
    GWT guarantees that the generated JavaScript app behaves exactly like the Java app
    And it does (most of the time)
  • 8. 4 easy pieces
    Java-to-JavaScript compiler
    Generates JS code from Java source
    Performs many optimization
    JRE emulation library
    GWT compatible version of most used Java core classes (java.lan, java.util)
    Java libraries
    Utility classes (JSON, I18N, …)
    Widget library
    Hosted Development mode
    Run/debug the app as Java bytecode
  • 9. Key benefits
  • 10. Easy development
    During development, you are writing and running a classic Java app
    Use your favorite IDE
    All IDE features available (code completion, code analysis, refactoring, links, Javadoc, …)
    Plugins help GWT-specific tasks
    launching development mode
    creating projects, modules, RPC services, …
    even design GUI (GWT Designer from Instantiations)
  • 11. More benefits
    Easy RPC implementation / consumption / deployment
    Easy JSON / XML parsing
    Easy UI building / widget reuse
    Easy history support
    Easy i18n
    Easy debugging
    Easy testing
  • 12. Any room for improvement???
    Of course…
  • 13. New in GWT 2.0
  • 14. Speed tracer
    Performance analysis tool
    Visualize where your app spends time:
    JS execution
    Browser rendering
    CSS handling (style selection/calculation)
    DOM handling / event processing
    Resource loading
  • 15. Speed Tracer: example
  • 16. In-browser development mode
    Before 2.0: hosted mode uses customized browser engine
    Heavily customized
    Only one supported browser per platform (IE on Windows, WebKit on Mac, Mozilla on Linux)
    Difficult to keep up-to-date
    Includes platform-specific code (SWT)
    Browser and hosted application share the same process
    Most plugins don’t work (including Google Gears…)
  • 17. In-browser development mode
    Hosted mode shell runs outside browser
    Communicates with browser using plugin through TCP
  • 18. In-browser development mode
    Use any (supported) browser/version on any platform
    Currently Safari, Firefox, IE, Chrome (not on OS X!)
    Behavior closer to web mode
    No interference with browser plugins
    No more platform-specific stuff in GWT (one jar for all!)
    Network protocol between shell and browser  cross-platform dev possible
    Dev mode shell on machine X, slave browser on machine Y
    E.g. dev on Linux, test in IE on Windows…
  • 19. Initiating dev mode
  • 20. Plugin installation
  • 21. Code splitting
    Before: monolithic download can become very big
    Slow startup times
    Programmer can insert “split points” in code
    Hints for the compiler to place everything not required up to split point in separate download
    Compiler divides code in several “chunks”, which are loaded on-demand
    Initial loading time reduced 50% on average with a single split point
    Allows on-demand module loading (provider pattern)
  • 22. Specifying a split point
    GWT.runAsync(newRunAsyncCallback() {
    publicvoidonFailure(Throwable reason) {
    // …
    public void onSuccess() {
    // ..
  • 23. Pattern: AsyncProvider
    publicinterfaceAsyncClient<P> {
    voidonUnavailable(Throwable reason);
    void onAvailable(P instance);
  • 24. Async provider: Implementing the provider
    publicclass Provider {
    privatestatic Provider instance = null;
    public static void getAsync(finalAsyncClient<Provider> client) {
    GWT.runAsync(newRunAsyncCallback() {
    public void onFailure(Throwable reason) {
    public void onSuccess() {
    if (instance == null) {
    instance = new Provider();
  • 25. Async provider: Loading the provider
    privatevoidloadProvider() {
    Provider.getAsync(newAsyncClient<Provider>() {
    publicvoidonAvailable(Provider provider) {
    publicvoidonUnavailable(Throwable reason) {
    Window.alert(”Failed: " + reason);
  • 26. Compile Report (formerly: SOYC)
    Better understanding of the compilation process
    Helps tuning code splitting
    Simple compiler flag
    Produces HTML report
    Sizes per chunk, package, etc.
    Compiler flag: -compileReport
  • 27. Compile Report: output
  • 28. Declarative UI: UiBinder
    Declarative construction of GUI using XML grammar
    Mix HTML and widgets
    Clearly separate responsibilities  better collaboration
    Static UI construction (XML)
    Dynamic UI behavior (Java)
    More efficient
    HTML vs DOM API calls
    Easy to transition from static HTML to dynamic
  • 29. UiBinder: define layout
    XML file (xx.ui.xml)
    <gwt:Labeltext="Sexe :" />
    <gwt:RadioButtonname='sexeradio' text='M’ />
    <gwt:RadioButtonname='sexeradio' text='F’ />
  • 30. UiBinder: instantiate
    publicclass SexeRadio2 extends Composite {
    extendsUiBinder<Panel, SexeRadio2> {}
    privatestaticfinalMyUiBinderbinder = GWT.create(MyUiBinder.class);
    public SexeRadio2() {
    finalPanel panel =binder.createAndBindUi(this);
  • 31. UiBinder: bind fields
    Automatically assign references to dynamically created widgets to designated Java fields (@UiField)
    XML :
    <gwt:RadioButtonname='sexeradio' text='M’ ui:field='maleRadio' />
    <gwt:RadioButtonname='sexeradio' text='F’ ui:field='femaleRadio'/>
  • 32. UiBinder: bind handlers
    Automatically attach event handlers (@UiHandler)
    Widgets only (not DOM elements)
    Handler type inferred from parameter type
    voidmaleClicked(ClickEvent event) {
    GWT.log("C'est un garçon!", null);
  • 33. More UiBinder goodness
    Mix HTML and widgets in same XML file
    Define CSS styles with <ui:style>
    Inline / external
    Apply to widgets with attributes styleNames / addStyleNames
    Programmatic access to styles (works with CssResource)
    Use external resources (images, CSS stylesheets, …) declared as client bundles with <ui:with>
    Instantiate widgets that don’t have zero-arg constructor with @UiFactory
  • 34. Resource bundles
    Download multiple heterogeneous resources from server in a single request
    Images (similar to ImageBundle in 1.x)
    Any other resource
    Fewer round trips to the server
    Less overhead
    More responsive interface
  • 35. Resource bundles: general mechanism
    Familiar mechanism
    Coding time: define interface
    Method type constrains resource type
    Method name (accessor) designates resource
    Annotation @source specifies resource content
    If unspecified, source is derived from accessor
    I18N aware (append _fr, _fr_FR)
    Runtime: access resource
    Obtain instance via GWT.create(interface.class) and call accessor directly
    Reference accessor through other mechanism (CSS injection @sprite, etc.)
  • 36. Resource bundles: DataResource
    Works with any kind of source
    Make the resource available through a URL
    Rename file to make resulting URL strongly-cacheable if appropriate
    XXX.pdf AAA12345.cache.pdf
    Webserver should be configured accordingly
  • 37. Resource bundles: TextResource
    Access to static text content
    TextResource is inlined into JavaScript
    ExternalTextResource is fetched asynchronously
    interface Resources extendsClientBundle {
    Resources INSTANCE = GWT.create(Resources.class);
    TextResource text1();
    ExternalTextResource text2();
  • 38. Accessing TextResouce
    // TextResource
    newResourceCallback<TextResource>() {
    publicvoidonError(ResourceExceptione) { ... }
    publicvoidonSuccess(TextResourcer) {
  • 39. Resource bundles: ImageResource
    Optimize runtime access to image data
    Transparently group /split images
    Uses ImageIO library
    Use in injected CSS with @sprite directive
    Supports most image formats
    Including animated GIF
    Not an image-processing library!
  • 40. Resource bundles: CssResource
    Define an extension of CSS
    Syntax validations / compile-time optimizations
    Injected at runtime
    Write CSS stylesheet
    Extend CssResource
    interfaceMyCssextendsCssResource {
    Include in ClientBundle
    interfaceMyResourcesextendsClientBundle {
    Use GWT.create(MyResources.class) to obtain instance of bundle
    Call CssResource.ensureInjected() to inject stylesheet in page
  • 41. CSS extensions
    Sprites with @sprite
    classMyResourcesextendsClientBundle {
    @sprite .mySpriteClass{
    gwt-image: "imageAccessor”
  • 42. CSS extensions
    Constants with @def
    Runtime evaluation with @eval and value()
    Conditional CSS with @if/@elif/@else
  • 43. Layout panels
    Layout panels
    Predictable, consistent layout
    Constraint based system built on top of CSS
    Plays nice with custom CSS styles
    Each child must have 0 or 2 constraints per axis
    Horizontal: none, left/width, right/width, left/right
    Vertical: none, top/height, bottom/height, top/bottom
    no constraint = fill parent
    Any unit (%, px, …)
    Must be added to an instance of ProvidesResize
    typically RootLayoutPanel
  • 44. Layout Panels
    • Easily usable with UiBinder
    <g:layer left=‘25% right=‘25%’ top=‘10px’ bottom=‘0’>
    Bunch of specialized panels implemented as LayoutPanels:
    DockLayoutPanel, SplitLayoutPanel, StackLayoutPanel, TabLayoutPanel
  • 45. And also…
    Compiler optimizations
    Most notably reduces generated JS size (expect 3-20 %)
    Draft compile mode: flag -drafCompile
    No optimizations / Faster builds
    Not for deployment!
    No more dependency on SWT
    No native code / browser required
    HtmlUnit: GUI-less browser written in Java
  • 46. Pointers, Conclusion, etc.
  • 47. Pointers
    GWT home (downloads, docs, FAQs, guides, etc.)
    Google groups “GWT” group
    onGWT: fresh news about GWT
    LinkedIn “GWT Users” group
  • 48. Shameless self-promotion
  • 49. Thank you
    twitter: @ogerardin