Javantura 2014 - Java 8 JavaScript Nashorn
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This document discusses Java 8's Nashorn JavaScript engine. It provides an overview of Nashorn, comparing it to previous JavaScript engines like Rhino. Nashorn is a new implementation of JavaScript for the JVM that is compiled rather than interpreted, resulting in much better performance and smaller memory footprint compared to Rhino. The document also discusses how Nashorn enables JavaScript to be used with Java technologies and provides some examples of Nashorn usage.
Javantura 2014 - Java 8 JavaScript Nashorn
- 1. Java 8 JavaScript Nashorn @MiroslavResetar, Javantura, 22.2.2014.
- 2. 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 • • Dart • • „writing JavaFX scripts in Nashorn is very easy” transkompajlira se u JavaScript! Vert.x • JavaScript API
- 3. Popularnost JavaScripta? • Redmonk, siječanj 2014. • Github repozitoriji vs Stack Overflow 1. JavaScript (+1) 2. Java (-1) 3. PHP 4. C# (+2) 5. Python (-1)
- 4. 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
- 5. 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
- 6. 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
- 7. 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 )
- 10. 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);
- 11. Kako do Nashorn-a? • JSR 223 – javax.script (Java 6, 12/2006)
- 13. QUnit • „QUnit is a powerful, easy-to-use JavaScript unit testing framework.” • Dohvati engine, učitaj QUnit, setupiraj ga, pokreni test
- 14. {{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.”
- 15. Shell scripting: JJS • Curl -> Regex -> Curl -> Play Audio
- 16. 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
- 17. „Meet the team”
- 18. 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.
- 19. 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 singlethreaded (exactly as in Node.js).” • „Avatar - JavaScript services layer...rich client side framework that assumes very minor JavaScript knowledge.”
- 20. 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-oraclejavamagazine-jan-feb-2014/
- 21. Pitanja?
- 22. Reference • Kod - https://github.com/mresetar/javantura-nashorn • JUnit benchmarks - http://labs.carrotsearch.com/junitbenchmarks-tutorial.html • Nashorn JavaFx debugger https://github.com/wickund/nashornexamples/ • Spring boot sample project • Rhino QUnit setup • VoiceRSS service