gwt@jazoon08 - part 4/6 - attention to detail

LOGO SPEAKER‘S COMPANY

# 4

attention to detail.

LOGO SPEAKER‘S COMPANYmake quality evident in everything ...


your Porsche may drive better but ...


create delightfull experiences ...


annoying.

ajax stuff you can’t bookmarkbroken back buttonserror type 11page that crashes during submit, what now?


history.[ for dummies ]


LISTEN TO HISTORY EVENTS

public class Example implements EntryPoint, HistoryListener {

public void onModuleLoad() {

History.addHistoryListener(this);

}

public void onHistoryChanged(String historyToken) { ... }

}

CREATE HISTORY EVENTS

History.newItem(“profile”); = http://localhost:8080/example#profile

History.newItem(“search”); = http://localhost:8080/example#search

History.newItem(“edit”); = http://localhost:8080/example#edit


history.[ demystified ]


BEHIND THE SCENES

browser history does not only effect top level pages browser history also works for iFrames History maintains a stack of applied tokens these tokens can be used to map to specific application state

background timer which check each ¼ of a second if $wnd.location has changed, if so it triggers the History listener (onHistoryChanged)


error handling.[ best practices ]


CATCH UNCAUGHT EXCEPTIONS

catch exceptions at the top-level just before they escape to the browser useful for event callbacks, timers, rpc… which are hard to try / catch

GWT.setUncaughtExceptionHandler(new GWT.UncaughtExceptionHandler() { public void onUncaughtException(Throwable e) { Window.alert(“You thought you could get away didn’t you !!!"); } });


STANDARDIZE EXCEPTION HANDLING

public abstract class ApplicationAsyncCallback<T> implements AsyncCallback<T> {

public final void onSuccess(T object) { onSuccessInternal(object);

}

public final void onFailure(Throwable throwable) { onFailureInternal(throwable);

Window.alert(“KABOEMMMM”); }

protected void onSuccessInternal(T object) {}

protected void onFailureInternal(Throwable throwable) {} }


LOG, LOG, LOG, LOG EVERYWHERE (1/4)

Log.debug(“Some log message”);

public class Log {

private static final Logger logger = GWT.isScript() ? new com.FireBugLogger() : new HostedModeLogger();

public static void debug(String message) { log(DEBUG, message); }

protected static void log(Level level, String message) { if (enabled && level.getWeight() <= getMaxLevel().getWeight()) { switch (level) { case ERROR: logger.error(message); break; case WARN: logger.warn(message); break; case INFO: logger.info(message); break; case DEBUG: logger.debug(message); break;



// request log level at runtime http://localhost:8080/x.html?log.level=error public static native String getLoglevel() /*-{

var level; var args = $wnd.location.search; var startLang = args.indexOf("log.level"); if (startLang >= 0) { var value = args.substring(startLang); var begin = value.indexOf("=") + 1; var end = value.indexOf("&"); if (end == -1) { end = value.length; } level = value.substring(begin, end); } return level; }-*/;



public class FireBugLogger implements Logger {

private boolean fireBugInstalled = false;

protected FireBugLogger() { checkIfFireBugInstalled(); }

protected native void checkIfFireBugInstalled() /*-{ [email protected]::fireBugInstalled = (typeof console != 'undefined'); }-*/;

public native void debug(String message) /*-{ if ([email protected]::fireBugInstalled) console.debug(message); }-*/;



public class HostedModeLogger implements Logger {

public void debug(String message) { log(toMessageWithLineInformation("DEBUG", message)); }

public void log(String message) { GWT.log(message, null); }

private String toMessageWithLineInformation(String logLevel, String message) { StackTraceElement line = new Throwable().getStackTrace()[4]; return (logLevel + " " + toLine(line) + ": " + message); }

private String toLine(StackTraceElement line) { return line.getClassName() + "(" + line.getLineNumber() + ")"; }


what’s wrong with the log example?


AUTOMATED USER ACCEPTANCE TESTS WITH SELENIUM

your code

Label firstnameLabel = new Label(); label.ensureDebugId(“firstnameLabel”); // if not enabled does nothing

enable debug mode – go Selenium gooooo…..

<inherits name=“com.google.gwt.user.Debug”/> // DOM.setElementProperty(…)

under the hood – UIObject

private static DebugIdImpl debugIdImpl = GWT.create(DebugIdImpl.class);

public static void ensureDebugId(Element elem, String id) { debugIdImpl.ensureDebugId(elem, id); }


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gwt@jazoon08 - part 4/6 - attention to detail

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