designing a javafx mobile application
DESCRIPTION
TRANSCRIPT
Designing a JavaFX Mobile application
Fabrizio Giudici
Tidalwave s.a.s.
214
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AGENDA
> Putting JavaFX (Mobile) in context
> My case study
> Main features of JavaFX (Mobile)
> JavaFX Mobile through a few examples
> Current status of JavaFX Mobile
> Conclusion
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About the speaker
> Senior Architect, Mentor, Technical Writer
> Working with Java (all the editions, plus exotic stuff) since 1996
> Working with Java ME since 1999
– First J2ME edition at JavaOne™ (Palm)
– Developed a couple of research projects with the University of Genoa
– Developed a couple of customer projects with my former company
– Consulting for customer projects
– Author of mobile FLOSS: windRose and blueBill Mobile
> Co-leader of JUG Milano
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What's wrong with JME
> Everything was so good at the old, Palm times
– Small devices → no big expectations
– One reference platform
– One pervasive runtime
> With more devices, JME got fragmented
– JSR as extension points (e.g. bluetooth, location)
– Multiple combinations
– Harder and harder to test
– windRose pain
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Hoping in Java FX Mobile
> JavaFX announced by Sun Microsystems in 2007
– A specific scripting language + a runtime
– Fight the “Ugly Java UI stereotype”
– Re-designed UI controls
– Integration with graphics designers workflow (e.g. NetBeans + Photoshop)
– Profiles for multiple targets (desktop / web, mobile)
> JavaFX Mobile profile
– Can sit on top of JME (MSA: Mobile Service Architecture, a.k.a. JSR-248)
– Maybe no more (or reduced) fragmentation?
> Oracle commitment after the Sun buy
> A fulfilled promise?
– Answers at the end :-)
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My case study: blueBill Mobile
> “The field tool for birdwatchers”
– Records geotagged observations
– Reference guides with multimedia
– Social capabilities (à la Google Friends)
> Started in 2009 with JavaFX
> Currently the most advanced version is the Android one
– JavaFX version being redesigned (more later)
> Demo
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Main features of JavaFX
> The languages is both imperative and declarative
– Imperative: for normal processing
– Declarative: mostly for the UI (no XML, no separate layout descriptor) Binding
– Has got closures, mixins
> Compiles to the same VM bytecode
– Can mix with Java code (e.g. reference a Java library)
– On the desktop, can be mixed with Swing (in addition to its own UI widgets)
– On the mobile, runs its own UI widgets
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Some code examples
> Example 1: Calling JME code
> Example 2: Posting contents (REST)
> Example 3: Getting resources (REST)
> Example 4: Binding (if time allows)
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Example: calling JME code
> Not much to say: it just workspackage it.tidalwave.bluebillmfx;
import javax.microedition.location.Criteria;import javax.microedition.location.LocationProvider;import javafx.animation.Timeline;import javafx.animation.KeyFrame;import it.tidalwave.geo.mapfx.model.Coordinates;
public class PositionTracker { public-read var currentPosition : Coordinates; def criteria = new Criteria(); var locationProvider : LocationProvider;
postinit { locationProvider = LocationProvider.getInstance(criteria); pollingTimeline.play(); }
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Example: calling JME code
> Need to copy data in JavaFX classes if you want binding support function getPosition(): Void { def location = locationProvider.getLocation(5); // JME stuff def coordinates = location.getQualifiedCoordinates();
if (coordinates != null ) { def lat = coordinates.getLatitude(); def lon = coordinates.getLongitude(); currentPosition = Coordinates { latitude: lat; longitude: lon }; } }
def pollingTimeline = Timeline { repeatCount: Timeline.INDEFINITE keyFrames: KeyFrame { time: 10s; action: periodicTask } };
function periodicTask(): Void { getPosition(); // update the map position, etc... } }
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Example: posting contents
> HttpRequest provides a skeletonpublic class ObservationRDFUpload extends HttpRequest { public-init var serviceURL = "http://myHost:8084/blueBillGeoService";
override public var method = HttpRequest.POST;
public var content : String; override var output on replace { if (output != null) { output.write(content.getBytes()); output.close(); } } override function start(): Void { location = "{serviceURL}/postObservation"; // REST call setHeader("Content-Type", "application/rdf"); super.start(); } }
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Example: posting contents
> HttpRequest provides a skeleton
def upload = ObservationRDFUpload { content: // ... assemble the string with the contents };
upload.start();
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Example: reading resources
> The relevant model classpublic class Taxon { public-read protected var id : String; public-read var urlsLoaded = false; var urlsLoading = false; var imageURLs : String[]; // [] is a list (“sequence”), not an array var images : DeferredImage[];
public bound function getImage (index : Integer): DeferredImage { def dummy = loadImageURLs(); // assignment is a requirement for the bound function return images[index]; }
public bound function imageCount(): Integer { return sizeof images; }
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Example: reading resources
> Getting a JSON resource catalog function loadImageURLs(): Boolean { if (not urlsLoading and not urlsLoaded) { urlsLoading = true; def fixedId = clean(id); // get rid of/escape “bad” chars such as :, #, etc... def url = "http://kenai.com/svn/bluebill-mobile~media/catalog/{fixedId}.json"; def request : HttpRequest = HttpRequest { // mere instantiation, not subclassing! location: url; method: HttpRequest.GET;
onInput: function (is: InputStream) { // hey, this is not a switch() label! if (request.responseCode != 200) { imageURLs = "media/black_glossy_web20_icon_012.png"; } else { try { def parser = PullParser { documentType: PullParser.JSON; input: is; onEvent: parseEventCallback }; parser.parse(); } catch (e: Exception) { println("Exception {e} while parsing {url}"); } finally { is.close(); } } }
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Example: reading resources
> Getting a JSON resource catalog onException: function (e: Exception) { imageURLs = "media/black_glossy_web20_icon_012.png"; urlsLoaded = true; }
onDone: function() { images = for (url in imageURLs) { DeferredImage { url: url }; }
imageURLs = null; urlsLoaded = true; } }
request.start(); }
return urlsLoaded; }
def parseEventCallback = function (event: Event): Void { if ((event.type == PullParser.TEXT) and (event.name == "url")) { insert event.text into imageURLs; } } }
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Example: reading resources
> Loading an image
> JavaFX Image loads automatically when initialized
var imageCounter = 0;public class DeferredImage { public-init var url : String; public-read var progress = bind image.progress; public-read var error = bind image.error; def id = imageCounter++; public-read var image : Image;
public function load() { // start loading only when load() is called if (image == null) { image = Image { url: url backgroundLoading: true } } } }
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Example: binding
> Introducing TaxonSearchController
– Manages a list of Taxons
– Produces a filtered list of Taxons whose names match a substring
– Provides a hint for autocompletion Eg. you type “He” That matches only “Heron ***” Hints is “Heron “
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Example: binding
> Some relevant parts of Taxonpublic class Taxon { public-read protected var displayName : String; public-read protected var scientificName : String; public-read protected var id : String;
override function toString() { return "{displayName} ({scientificName}) ({id})" } }
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Example: binding
> TaxonSearchController (1/3)public class TaxonSearchController { public var taxons: Taxon[]; public var filteredTaxons: Taxon[]; public var selectedTaxonIndex : Integer = -1; // set from the UI
public var selectedTaxon = bind if (selectedTaxonIndex < 0) then null else filteredTaxons[selectedTaxonIndex];
// setting this property will trigger filtering public var filter = "" on replace { filteredTaxons = taxons[taxon | matches(taxon, filter)]; updateHint(); }
public-read var hint = ""; // the auto-completed hint
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Example: binding
> TaxonSearchController (2/3) protected function matches (taxon : Taxon, string: String) : Boolean { if (string == "") { return true; } if (taxon.displayName.toLowerCase().startsWith(string.toLowerCase())) { return true; // more complex in the real case, as it also deals with scientific name // but not relevant now } return false; }
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Example: binding
> TaxonSearchController (3/3) protected function updateHint(): Void { def hintTry = commonLeadingSubstring(filteredTaxons); // // Sometimes it can't find a better auto-completion than the current filter, // hint = if (hintTry.length() > filter.length()) then hintTry else filter; }
}
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Example: binding
> TaxonSearchScreenpublic class TaxonSearchScreen extends Container // e.g. a UI panel { // warning: there are some simplifications, but the concepts are here public-read def controller = TaxonSearchController { selectedTaxonIndex: bind list.selectedIndex; } def list = ListBox { // the list widget in the UI items: bind controller.filteredTaxons };
def hint = bind controller.hint on replace { if (hint != "") { filter = hint; } } var resetSelectionWhenFilterChanges = bind controller.selectedTaxon on replace { if (controller.selectedTaxon != null) { list.selectedIndex = 0; } } TextBox { // a text input box in the UI text: bind controller.filter with inverse } Text { // a label rendering a text in the UI content: bind "{sizeof controller.filteredTaxons} specie(s)" }
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JavaFX mobile in 2009
> Development tools available (emulator, etc...)
> First capable phones at J1: LG Incite, HTC Touch Diamond
> Announced a “JavaFX Mobile player”
– Would run JavaFX on MSA (JSR 248) JME phones
> Looked very promising
– That's why blueBill Mobile started with it
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Status updates in 2010
> Barcelona Mobile World Congress 2010
– “Feature phones” (Qualcomm and the Brew Mobile Platform OS)
– Sony-Ericsson in “upcoming phones”
> Recent phone status update (JavaFX forums, March 16, 2010)
– LG Incite, HTC Touch Diamond... still!
– “Unofficially” runs on any Windows Mobile 6.x device (e.g. HTC HD2)
> JavaFX 1.3 released on May 14, 2010
– Shares many improvements with the desktop/web profile
– Mobile emulator runs on Mac OS X
> JavaFX Mobile Player MIA (I mean, it's Windows Mobile only)
> No further manufacturer endorsements?
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My view of Java-related mobile solutions
> We're in the climax of the “next generation mobile” war
– iPhone/iPad, Android leading on the growth rates
– Adobe Flash at stake, but if it survives will be relevant
> Is there still room for JavaFX Mobile? JME?
> JavaFX Mobile
– Still excites me, technically
– The Oracle-Sun deal might have slowed down deals – but...
– … timing out this Summer
– Hoping in a specific Android port/adaptation (using the Android UI/runtime) Hearing a few people talking about that Would bring-in e.g. the integration with graphic designer workflow
> JME still relevant for the “glorious old guard” (Nokia, etc..., BlackBerry)
– “Oldies but goodies”
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My research for the Summer
> Two/threefold strategy
– Android (it delivers, short time-to-market)
– JME (catch the “old glorious guard”)
– JavaFX (if industry endorsements / Android support will show up)
> Study whether it is possible to reuse code
– Not thinking of “catch-all” frameworks
– Reusing only the models, writing ad-hoc UIs (no “GCD syndrome”)
– Maven for re-using artifacts
– Byte-code manipulation (e.g. RetroWeaver) for fitting JME Java 1.3?
– Follow my blog and my space at Dzone.com
> The “new” blueBill Mobile for JavaFX code is not yet available
– Under heavy refactoring, catching up with the Android version
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Questions?
> Thanks for your attention
– http://javafx.com
– http://bluebill.tidalwave.it/mobile
– http://windrose.tidalwave.it
