Accessing RESTful Web Services from the JavaFX™ Script ......XML & JSON Parser RSS & Atom...

Accessing RESTful Web Services from the JavaFX™ Script Platform

Akhil Arora & Kinsley WongSun Microsystems, Inc.

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Agenda

Asynchronous HTTPXML & JSON ParserRSS & Atom API

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Introduction

All APIs are in the Common profile● identical API for desktop, mobile, TV

This presentation is based on APIs in JavaFX SDK version 1.2

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Agenda

Asynchronous HTTPjavafx.io.http

XML & JSON ParserRSS & Atom API

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HttpRequest

Asynchronous HTTP client API with progress indicators and callbacksdef http = HttpRequest { location:“http://javafx.com” method:HttpRequest.GET}http.start()

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HttpRequest: Progress Indicators

State Transitions (false → true)► started► connecting // status = “connecting...”► doneConnect► writing // status = “writing data...” (if POST or PUT)► doneWrite► readingHeaders► doneHeaders // if (responseCode != HttpStatus.OK) ...► reading // status = “reading data...”► doneRead► done

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HttpRequest: Progress Callbacks

State Transitions via callbacksonConnecting:function() { status = “connecting...” }onWriting:function() { status = “writing data...” }onReading:function() { status = “reading data...” }onResponseCode:function(code:Integer) { if (code != HttpStatus.OK) { status = “failed:{request.responseMessage}” }}

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HttpRequest: Read Progress

Using bind► toread:Long // -1 if content-length header is not set► read:Long // updated as bytes are readif (toread > 0) percent = (read * 100) / toread

Using callbacksvar max;onToRead:function(bytes:Long) { max = bytes }onRead:function(bytes:Long) { if (max > 0) percent = (bytes * 100) / max}

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HttpRequest: Write Progress

Using bind► towrite:Long // -1 if not available► written:Long // updated as bytes are writtenif (towrite > 0) percent = (written * 100) / towrite

Using callbacksvar max;onToWrite:function(bytes:Long) { max = bytes }onWritten:function(bytes:Long) { if (max > 0) percent = (bytes * 100) / max}

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HttpRequest: Reading Data

Using bind► input:java.io.InputStream

Using callbackonInput:function(is:java.io.InputStream):Void { try { println(“{is.available()} bytes available”) } finally { is.close() }}

> data is cached, so reader will not block> must close stream after use

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HttpRequest: Writing Data

Using bind► output:java.io.OutputStream

Using callbackonOutput:function(os:java.io.OutputStream):Void { try { os.write(“my data”.getBytes()) } finally { os.close() } }

> writes are cached, so writer does not block> must close stream after use, which also initiates

the actual sending of data over the network

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HttpRequest: Bulk Data Read

For downloading large data, typically mediaSpecify a destination for data and start as usual

► sink:java.io.OutputStreamdef bos = new java.io.ByteArrayOutputStream()def http = HttpRequest { location:“http://javafx.com” sink: bos}http.start()

when done, bos should contain the contents of javafx.com

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HttpRequest: Bulk Data Write

For uploading large data, typically mediaSpecify a source of data and start as usual

► source:java.io.InputStreamdef is = ... // image or video streamdef http = HttpRequest { location:“http://cloud.sun.com/uploads” method:HttpRequest.POST headers:[HttpHeader.basicAuth(user,password)] source:is}http.start()

when done, the contents of is should be available at the upload location specified

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HttpRequest: Setting Request Headers

Set the headers var to set HTTP request headers► headers:HttpHeader[]headers: [ HttpHeader { name:HttpHeader.CONTENT_TYPE value:”image/jpeg” }, // convenience function for creating an HTTP Basic Auth header HttpHeader.basicAuth(username, password)]

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HttpRequest: Get Response Headers

Get all header names and values► responseHeaders:HttpHeader[]

Using callback► onResponseHeaders:function(headerNames: String[])

Get specific header by name► getResponseHeaderNames():String[]► getResponseHeaderValue(name:String):String

Exampledef etag = getResponseHeaderValue(HttpHeader.ETAG)

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URL Encoding and Decoding

Encoding and Decoding of URL ParametersCan customize delimiters and specify options

► encodeAsterisk► encodeSpaceAsPercent

def params = [ Pair{name:”symbol” value:”JAVA”}, Pair{name:”from” value:”oct, 1 2008”}, Pair{name:”to” value:”nov, 1 2008”} ]def converter = URLConverter {}def url = “http://quoteservice.com?” converter.encodeParameters(params);// assert url == “http://quoteservice.com?symbol=JAVA&from=oct%2C+1+2008&to=nov%2C+1+2008

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Agenda

Asynchronous HTTPXML & JSON Parser

javafx.data.pulljavafx.data.xml

RSS & Atom API

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PullParser

Mobile-friendly - does not build a Document Object Model in memory

Generates a sequence of Events as it processes the document

Works in pull mode, but can also emulate pushCan jump forward to elements of interestIdentical API for XML and JSON

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Levels (or Depth)<Result> <Rating> <AverageRating>4.5</AverageRating> </Rating> <Distance>2.67</Distance></Result>"Result":[ {"Rating": {"AverageRating":"4.5"}, "Distance":"2.67" }}

Result is at level 0Rating, Distance are at level 1

AverageRating is at level 2

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Parser Events and LevelsSTART_DOCUMENTSTART_ELEMENT 0 “Result” START_ELEMENT 1 “City” TEXT 1 “Palo Alto” END_ELEMENT 1 “City” START_ELEMENT 1 “State” TEXT 1 “CA” END_ELEMENT 1 “State”END_ELEMENT 0 “Result”END_DOCUMENT

<Result> <City>Palo Alto</City> <State>CA</State></Result>

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PullParser

The PullParser class► documentType: PullParser.XML► input: ... // a java.io.InputStream that contains XML► encoding: “utf-16” ► ignoreWhiteSpace: true► event:Event► onEvent:function(event:Event):Void

documentType can be JSON or XML (default)encoding defaults to utf-8ignoreWhiteSpace defaults to false

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Parser Events

The Event class► type:Integer► typeName:String► level:Integer► qname:QName // XML► name:String // JSON► getNamespacePrefixes():String[]► getNamespace(prefix:String)► getAttributeNames():QName[]► getAttributeValue(name):String

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Seeking Happiness

Problem: what is the value of happiness?<world> <self> <happiness>... is a state of mind.</happiness> </self></world>

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Looking for Happiness

Problem: what is the value of happiness?<world> <self> <happiness>... is a state of mind.</happiness> </self></world>

Strategy 1: look for happinesswhile (parser.event.type != PullParser.TEXT and parser.event.qname.name != “happiness” and parser.event.level != 2) { parser.forward() }def happiness = parser.event.text// assert happiness == “... is a state of mind.”

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Emulating Push

Strategy 2: wait for happiness to be sent your wayvar happiness:String;PullParser { input: ... onEvent: function(event:Event) { if (event.type == PullParser.TEXT and event.qname.name == “happiness” and event.level == 2) { happiness = event.text } }}.parse();// assert happiness == “... is a state of mind.”

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Seeking Happiness

Strategy 3: seek happinessparser.seek(“happiness”, 2); // now at START_ELEMENTparser.forward(); // now at TEXTdef happiness = parser.event.text// assert happiness == “... is a state of mind.”

Or simplydef happiness = parser.seek(“happiness”, 2).forward().event.text// assert happiness == “... is a state of mind.”

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JSON EventsSTART_DOCUMENTSTART_ELEMENT 0 START_VALUE “number” INTEGEREND_VALUE “number”START_VALUE “array” START_ARRAY START_ARRAY_ELEMENT TRUE END_ARRAY_ELEMENT END_ARRAYEND_VALUE “array”END_ELEMENT 0END_DOCUMENT

{ “number”:123, “array”:[true]}

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Agenda

Asynchronous HTTPXML & JSON ParserRSS & Atom API

javafx.data.feedjavafx.data.feed.atomjavafx.data.feed.rss

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Feed API

Mobile-friendly, streaming APIEach Entry or Item is delivered incrementally as

it is parsed● Atom: Feed followed by zero or more Entries● RSS: Channel followed by zero or more Items

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FeedTask

The FeedTask abstract classBase class for Atom and RSS Tasks

► location:String // feed URL► interval:Duration // poll interval► onException:function(ex:java.lang.Exception)► onForeignEvent:function(event:Event)

the onForeignEvent callback reports events that are not in the native namespace

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AtomTask

class AtomTask extends FeedTask► onFeed:function(feed:Feed)► onEntry:function(entry:Entry)

ExampleAtomTask { location:”http://blogs.sun.com/.../atom” interval:2h onFeed:function(feed:Feed) { title = feed.title.text } onEntry:function(entry:Entry) { show(entry) }}.start()

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RssTask

class RssTask extends FeedTask► onChannel:function(channel:Channel)► onItem:function(item:Item)

ExampleRssTask { location:”http://developers.sun.com/rss/javafx.xml” interval:1h onChannel:function(channel:Channel) { title = channel.title } onItem:function(item:Item) { show(item) }}.start()

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Summary

This presentation covered how to use the webservices APIs in JavaFX version 1.2 to

> fetch resources from the network over HTTP using the asynchronous HTTP client library

> extract information of interest from XML and JSON

> subscribe to RSS and Atom feeds and extract information from them to use in your own applications

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Resources

Learnhttp://javafx.com/learn

Samples that use JavaFX WebServices APIshttp://javafx.com/samples/InterestingPhotos/index.htmlhttp://javafx.com/samples/LocalSearch/index.htmlhttp://javafx.com/samples/ShoppingService/index.htmlhttp://javafx.com/samples/RSSViewer/index.html

Akhil Arora & Kinsley Wongakhil@sun.com kinsley.wong@sun.com