Java 8 JavaScript - Nashorn

@MiroslavResetar, Javantura, 22.2.2014.

JavaScript na Javanturi?

• Alfresco • CMIS API implementiran u JavaScriptu

• Neo4J • „people love to use Neo4j from Node.js and the browser”

• Sencha Touch, Ext.Js, D3.js,

• JavaFX • „writing JavaFX scripts in Nashorn is very easy”

• Dart • transkompajlira se u JavaScript!

• Vert.x • JavaScript API

Popularnost JavaScripta?

• Redmonk, siječanj 2014. • Github repozitoriji vs Stack Overflow

1. JavaScript (+1)

2. Java (-1)

3. PHP

4. C# (+2)

5. Python (-1)

JVM polyglot programming

• Clojure, Scala, JRuby, Jython, Rhino (JavaScript)

• Zašto JVM? • Jer je zakon • GC, Threads, Java API, ogromna količina biblioteka, puno

platformi

• JVM – najbolji dio Jave

Rhino

• Rhino – Java implementacija JavaScripta

• 1997 – Netscape započeo rad na Rhino-u

• 1998 – Rhino je predan Mozilli i open source-an

• 2006 – Java 6 pakira Rhino kao standardnu implementaciju skriptnog jezika

Problemi sa Rhino-om

• Rhino je veoma spor u usporedbi sa ostalim JavaScript engine-ima (browserima)

• Velika potrošnja memorije

• Veoma stari codebase (iz Java 1.1 vremena)

• Kako bi se „popravio” bio je potreban veliki rewrite, odluka je bila krenuti iz početka

Nashorn

• Potpuno nova implementacija JavaScripta • Kompajlirani kod a ne interpreter

• Dolazi standardno sa JDK-om 8

• 5 x manji footprint

• 20 x bolje performanse (otprilike )

Rhino vs Nashorn

Nashorn vs Groovy

InvokeDynamic

• A First Taste of InvokeDynamic • „... static nature of Java is in the language itself (and not the

JVM)” • „Every invocation has to be called against a known type.” • „we must generate hundreds of tiny methods into tiny

classes with everything neatly tied up in a bow so the JVM will pretty please perform that invocation for us as quickly as possible” • „java.lang.OutOfMemoryError: PermGen space”

• „InvokeDynamic ... the ability to make a dynamic call that the JVM not only recognizes, but also optimizes in the same way it optimizes plain old static-typed calls.” • MethodHandle happyTimeHandle = MethodHandles.findVirtual(Happy.class,

"happyTime", void.class, String.class);

Kako do Nashorn-a?

• JSR 223 – javax.script (Java 6, 12/2006)

Nashorn smoke test

QUnit

• „QUnit is a powerful, easy-to-use JavaScript unit testing framework.”

• Dohvati engine, učitaj QUnit, setupiraj ga, pokreni test

{{Mustache}}

• „Mustache is a logic-less template syntax. It can be used for HTML, config files, source code - anything. It works by expanding tags in a template using values provided in a hash or object.”

Shell scripting: JJS

• Curl -> Regex -> Curl -> Play Audio

Što Nashor nije

• Nije DOM/CSS okruženje • Ne podržava korištenje biblioteka kao što su JQuery, Dojo,

Ext. (out-of-the-box)

• Nema browser plugin API • Nije embeddable u browser

• Ne podržava ne standardizirane feature JavaScripta

• Nije multithreaded safe • generalno nije problem ukoliko se izbjegava globalni scope • loadWithNewGlobal creates a fresh global before loading

the script

„Meet the team”

Jim Laskey odgovara

• Postoji li debugger za Nashorn? • Debuger je integriran u Netbeans 8 (beta). • Eclipse još nema debugger za Nashorn.

• Da li radite još na poboljšanju performansi? • Da. Veliki trud se ulaže kako bi performanse bile još bolje sa

verzijom 8u20. Verzija se očekuje na jesen. Za sada su brojke obećavajuće.

• Što se događa sa Node.jar projektom? • Preimenovan u Avatar.js. StrongLoop ulažu ogroman trud ne

bi li podržali projekt. Trenutne performanse su bolje od Node.js. Bit će još bolje sa verzijom 8u20.

Project Avatar i Avatar.js

• „Avatar.js is a project to bring the node programming model, APIs and module ecosystem to the Java platform.”

• „Avatar.js applications are both asynchronous and single-threaded (exactly as in Node.js).”

• „Avatar - JavaScript services layer...rich client side framework that assumes very minor JavaScript knowledge.”

Želite znati više?

• Jim Laskey - Nashorn, JavaScript for the JVM • http://www.youtube.com/watch?v=I6eo2KPsk7U

• Attila Szegedi - The Curious Case of JavaScript on the JVM (http://vimeo.com/78890890)

• Oracle Java Magazine Jan/Feb 2014 – Oracle Nashorn • http://julien.ponge.org/blog/nashorn-article-in-oracle-

javamagazine-jan-feb-2014/

Pitanja?

Reference

• Kod - https://github.com/mresetar/javantura-nashorn

• JUnit benchmarks - http://labs.carrotsearch.com/junit-benchmarks-tutorial.html

• Nashorn JavaFx debugger - https://github.com/wickund/nashornexamples/

• Spring boot sample project

• Rhino QUnit setup

• VoiceRSS service