The Future is NighNews In the Upcoming Java 7

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Remember Java EE 5?

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Ease of Development FocusMajor Revamp of Programming Model

EJB™ 3.0 support for POJOs means less learn, less to code and less to maintain

New Java™ Persistence API makes object/relational mapping cleaner and easier

New and updated Web Services (JAX-WS 2.0 and JAXB 2.0) simplifies SOA implementation

JavaServer™ Faces 1.2 facilitates building Web 2.0 Applications with AJAX

Annotations often eliminates the need for deployment descriptors

Supported by NetBeans™ 5.5 Enterprise PackGet the SDK:

http://java.sun.com/javaee/downloads

History of Enterprise Java

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JPE Project

J2EE 1.2Servlet, JSP, EJB, JMS, RMI/IIOP

J2EE 1.3CMP,

Connector Architecture

J2EE 1.4Web

Services, Management, Deployment,

Async. Connector

Java EE 5Ease of

Development, Annotations,

EJB 3.0 Persistence

API, New and Updated Web

ServicesEnterpriseJava

Platform

Robustness

Web Services

Ease ofDevelopment

Theme for Java EE 6

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Rightsizingthe Platform<>

Rightsizing• “Ease of development is good, but…

… the platform still feels too big.”>Feedback: we want less bloat

• Reduce size, without losing focus• Make the platform fit a particular class of applications

well• Increase flexibility of deployment

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New in Java EE 6• Profiles• Pruning• Extensibility• More ease of development

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Pruning• Make some components optional• Send a strong message to application developers• Same rules as Java SE apply:

> “pruned now, optional in next release”• Likely candidates for pruning:

>EJB Entity Beans—Replaced by JPA>JAX-RPC—Replaced by JAX-WS>JAXR—Used Infrequently>JSR-88— Used Infrequently, not used by applications

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!“Java is boring”

Things We Like Withthe Java Language• Automatic Memory Management (GC)• Strong Typing• Object-Oriented• No Pointers• WORA• Run-Time Optimization• Rich Class Library• Static Typing (well, sometimes…)• Simple, Clean and Expressive

Things We Like Withthe JVM• Automatic Memory Management (GC)• Strong Typing• Object-Oriented• No Pointers• WORA• Run-Time Optimization• Rich Class Library• Static Typing (well, sometimes…)• Simple, Clean and Expressive

Languages For the JVM?

http://www.robert-tolksdorf.de/vmlanguages.html

Infiqs, Java+, BDC Scheme, Armed Bear Common Lisp (ABCL), Lili, Jatha, Bigloo, SISC, Lisp, PS3I, Scheme package, HotScheme, webLISP, Jaja, JScheme, Skij, Kawa, Jscheme, LispkitLISP Compiler, Lambda Calculus Interpreter, The UncommonLisp

Interpreter, uts, Grasshopper, Testalgo2, Mapyrus, MaVerickBASIC, CONVERT, JBasic, HotTEA, JavaBasic, COCOA, TSR-80 Model 1 BASIC, StarLogo, AJLogo, Turtle Tracks, rLogo, Yoyo, K.U.Leuven JCHR, TermWare, Drools, XProlog, tuProlog, PROLOG+CG, DGKS Prolog, JLog, Java Internet Prolog, NetProlog, CKI Prolog, JavaLog, Jinni, LLPj, LL, W-Prolog, jProlog, JESS-Java Expers System Shell, javalog, MINERVA, Kiev, Bruce, SmallWorld, SmalltalkJVM, Talks2, Bistro, G, Groovy, Nice, Scala, Anvil,

SmallWorld, SmalltalkJVM, Talks2, Bistro, G, Groovy, Nice, Scala, Anvil, Ephedra, dSelf, Hojo, foo, Correlate, MetaJ, Demeter/Java, Bolero, Sather, PERCobol, Ada,

JGNAT, FScript, Sleep, WLShell, Bambookit, JudoScript, JRuby, ObjectScript, Jickle, Yoix, Simkin, BeanShell, Dawn, DynamicJava, W4F, Netscript, Rhino,

PolyJsp, Resin, Iava, WebL, FESI, iScript, Jython, Pnuts, Yassl, Janino, JAsCo, Join Java, Kanaputs, Jam, JEX, JMatch, Javassist, Jiazzi, ArchJava, MultiJava,

Gilgul, dejay, Guarana, AspectJ, PolyJ, xkjc, Jass, Borneo, GJ, Jamie, Scriptic, OpenJava, Kiev, JavaParty, JAVAR, JAVAB, Pizza, myForth, Delta Forth, FIJI, Misty

Beach Forth, AMPC, Snobol3, Processing, Qexo, Frink, ANTLR, JavaCC, ZigZag, ComponentPascal, JOMP, Tea, Tiger, perljvm, f2j, Oberon, Luck, Occam, E, Assembler

Categories• Precompilers: 10• Tcl: 3• Functional: 6• LISP & Co.: 21• BASIC: 11• Logo: 5• Logic Programming: 19• Eiffel: 1• Smalltalk: 4• Various: 53

• COBOL: 1• Ada: 2• Scripting: 27• Extended Java: 31• Forth: 5• Assemblers: 4

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“Big” Changes from Sun• Modularization

>JSR-294>Project Jigsaw>JSR-277

• JVM Support for Dynamic Languages>JSR-292> invokedynamic

• New I/O 2>JSR-203>True asynchronous I/O>new file i/o

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More “Big” Changes from Sun• Language Changes

>Safe rethrow>Null dereference expressions>Better type inference>Multi-Catch

• Swing Application Framework>JSR-296

• Forward Port of Java 6u10 Features>Java Kernal>Quickstarter>New Applet plug-in

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“Small” Changes from Sun• SCTP (Stream Control Transmission Protocol)• SDP (Sockets Direct Protocol)• Upgrade Class Loader Architecture• Method for Closing a URLClassLoader• Unicode 5.0 Support• XRender Pipeline for Java2D• Swing Updates

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“Fast” Changes from Sun• G1 (Garbage First) Garbage Collector

>Shorter pause times>Replaces Concurrent mark and sweep (hopefully)

• Compressed pointer 64 bit VM• MVM-Lite

>Multiple Virtual Machine> Isolation> “kill -9” on a Java application

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Other Changes• Annotations on Java Types

>JSR-308>Driven by Prof. Michael Ernst and Mahmood Ali>ex. @NonNull

• Concurrency and Collections Updates>JSR-166>Fork/Join>Phasers>LinkedTransferQueue>ConcurrentReferenceHashMap>Fences

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Not in Java™7 (partial list)• Closures

>No consensus around a single proposal• Reified Generics• 1st Class Properties• Operator Overloading• BigDecimal Syntax• JSR-295 Beans Binding

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Superpackages

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superpackage example.bar.lib { // member packages member package example.bar.lib; // member superpackages member superpackage example.bar.lib.net, example.bar.lib.xml; // list of exported types export example.bar.lib.Table; export superpackage example.bar.lib.net; }

> invokedynamic <

JVM Architecture

runtime data areas

method area

class loader subsystem

heapJava

stackspc

registers

native method stacks

execution engine native method

interfacenative method

libraries

4 Bytecodes for Method Invocation• invokevirtual• invokeinterface• invokestatic• invokespecial

invokevirtual• General form:

> invokevirtual TargetObjectType.methodDescriptor> MethodDescriptor:

methodName(ArgTypes) ReturnType

• Very close to Java programming language semantics> Only overloading (and generics) left to javac> Single inheritance, single dispatch, statically typed

• Verifier ensures types are correct

invokevirtual TargetType.method(ArgType) ReturnType

Dynamically Typed Languages• Anything can be passed to a function/method

> No type information at compile time> No type information at byte code generation time (even

when doing Just-in-Time generation)> Type information only at run time

And Here the Troubles BeginConsider a trivial snippet of code in a dynamically typed language:

newSize(c)

// Collection has grown; figure out the next increment

// in size

{

return c.size() * c.growthFactor();

}

And Here the Troubles BeginConsider a trivial snippet of code in a dynamically typed language:

newSize(c)

// Collection has grown; figure out the next increment

// in size

{

return c.size() * c.growthFactor();

}

c.growthFactor()

And Here the Troubles BeginConsider a trivial snippet of code in a dynamically typed language:

newSize(c)

// Collection has grown; figure out the next increment

// in size

{

return c.size() * c.growthFactor();

}

c.growthFactor()

invokevirtual UknownType.growthFactor() UnknownReturnType

And Here the Troubles BeginSolution: synthetic interfaces

newSize(c)

// Collection has grown; figure out the next increment

// in size

{

return

((Interface91)((Interface256) c).size()) *

(Interface91) ((Interface42) c).growthFactor();

}

And Here the Troubles BeginSolution: synthetic interfaces

newSize(c)

// Collection has grown; figure out the next increment

// in size

{

return

((Interface91)((Interface256) c).size()) *

(Interface91) ((Interface42) c).growthFactor();

}

invokeinterface Interface42.growthFactor() Object

Solution: invokedynamic

• Target need not be statically known to implement method descriptor given in instruction> No need for a host of synthetic interfaces

• Actual arguments need not be statically known to match method descriptor> Instead, cast at invocation time to ensure integrity

• Will be added to the Java Virtual Machine as of Java7 (Dolphin)

A loosely typed invokevirtual

invokedynamic Anyclass.growthFactor() Object

invokedynamic, Cont.• The JVM won’t traverse the type hierarchy

> delegated to a plug-in written by the language designer> every language has it’s own rules for inheritance and

delegation> enables multiple inheritance> enables prototype based languages

Only a Partial Solution• No direct support for multiple inheritance or multiple

dispatch> General support is hard—each language has its own rules

• Calling Java platform libraries from scripting languages brings additional problems> How do you resolve overloading?

• However, invokedynamic is a useful primitive in most of these complex scenarios as well

invokedynamic/** * Syntactic marker interface for class- * based dynamic method selection. */package java.dyn;public interface Dynamic { // empty}

// Running example Java code which exercises Draft invokedynamicclass MyCaller { Object myMethod(Object x, Object y, int z) { // x . invokedynamic["alpha",(Object,int)Object] (y, z) return ((Dynamic)x).alpha(y, z); }}

void someMethod() throws X1,X2 { try { /* Something that can throw X1,X2 */ } catch (Throwable e) { logger.log(e); throw e; // Error: Unreported exception Throwable } }

Safe Re-Throw

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void someMethod() throws X1,X2 { try { /* Something that can throw X1,X2 */ } catch (Throwable e) { logger.log(e); throw e; // Error: Unreported exception Throwable } }

void m() throws X1,X2 { try { /* Something that can throw X1,X2 */ } catch (final Throwable e) { logger.log(e); throw e; // Compiles OK; can throw X1,X2 } }

Safe Re-Throw

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T x = null;if( a != null ) { B b = a.b(); if( b != null ) { C c = b.c(); if( c != null ) { x = c.x(); } }}

Null-Dereference Expression

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T x = null;if( a != null ) { B b = a.b(); if( b != null ) { C c = b.c(); if( c != null ) { x = c.x(); } }}

T x = a?.b()?.c()?.x();

Null-Dereference Expression

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Map<String,Integer> m = new HashMap<String,Integer>();

Better Type Inference

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Map<String,Integer> m = new HashMap<String,Integer>();

Better Type Inference

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Map<String,Integer> m = new HashMap<>();

try { ... }catch( X1 e ) { foo(); }catch( X2 e ) { foo(); }catch( X3 e ) { bar(); }

Multi-Catch

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try { ... }catch( X1 e ) { foo(); }catch( X2 e ) { foo(); }catch( X3 e ) { bar(); }

Multi-Catch

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try { ... }catch( X1, X2 e ) { foo(); }catch( X3 e ) { bar(); }

void foo(Bar x) { x.fum(); // Potential NullPointerException}

Annotations on Java Types

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void foo(Bar x) { x.fum(); // Potential NullPointerException}

Annotations on Java Types

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void foo(@NonNull Bar x) { x.fum(); // Statically Checked}

NIO 2

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import java.nio.file.*;

Path home= Path.get("/home/gus"); Path profile= home.resolve(".bash_profile");

// Backup existing file profile.copyTo(home.resolve(".bash_profile.backup"));

// Append useful stuff to the profile WritableByteChannel ch= profile.newSeekableByteChannel(APPEND); try { appendStuff(ch); } finally { ch.close();}

Concurrency and Collections• Doug Lea, Josh Bloch, et. al• Fork/Join framework• Phasers — Generalized barriers• LinkedTransferQueue — Generalized Queue• ConcurrentReferenceHashMap• Fences — Fine-grained read/write ordering

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Java 7 Release

Early 2010

Primary:ClosureLiteral

ClosureLiteral:{ FormalParametersopt => BlockStatementsopt Expressionopt }

Closures

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{int x, int y => x+y}

{int,int=>int} plus = {int x, int y => x+y};

Closures, examples

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public class DeepThought { // { => int } means a function with no arguments and return type int static { => int } answer = { => 42 };

public static void main(String[] args) { int i = answer.invoke(); System.out.println(i);

}}

Closures, further example

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SUN LABS PROJECT:

Maxine Open Source Research VM

• GNU General Public License version 2> License-compatible with OpenJDK™

• Currently builds on JDK 1.6 release• Not a fully compliant Java™ Virtual Machine (yet)

• Alpha release source code:

https://maxine.dev.java.net/

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SUN LABS PROJECT:

Maxine Platforms

• Supported:> Solaris™ Operating System / SPARC® Technology> Solaris / x64

> Mac OS X / x64

> Xen / x64

• Contemplated:> Xen / x32

> ARM

> PowerPC

> Windows

• Under development:> Solaris OS / x32

> Linux / x64

> Linux / x32

> Mac OS X / x32

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SUN LABS PROJECT:

Conventional vs. Meta-Circular

C/C++ etc.

JDK

Applications

Java Language

Native

Libraries

C/C++ etc.

ConventionalVM Native

Libraries

Java

Applications

Language

JDKMeta-Circular VM

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SUN LABS PROJECT:

Meta-Circular VM Design

• The VM is written in the same language it executes

• The VM uses JDK packages and implements their downcalls into the VM

• Built around an optimizing compiler (not an interpreter)

• The optimizing compiler in the VM translates itself

The Lisp Read-Eval-Print-Loop(defun eval (e a) (cond ((atom? e) (assoc e a)) ((atom? (car e)) (cond ((eq (car e) 'quote) (cadr e)) ((eq (car e) 'atom?) (atom? (eval (cadr e) a))) ((eq (car e) 'eq) (eq (eval (cadr e) a) (eval (caddr e) a))) ((eq (car e) 'car) (car (eval (cadr e) a))) ((eq (car e) 'cdr) (cdr (eval (cadr e) a))) ((eq (car e) 'cons) (cons (eval (cadr e) a) (eval (caddr e) a))) ((eq (car e) 'cond) (evcon (cdr e) a)) ('t (eval (cons (assoc (car e) a) (cdr e)) a)))) ((eq (caar e) 'label) (eval (cons (caddr e) (cdr e)) (cons (list (cadar e) (car e)) a))) ((eq (caar e) 'lambda) (eval (caddar e) (append (pair (cadar e) (evlis (cdr e) a)) a))) ) )

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SUN LABS PROJECT:

Multi-Language Potential

• Fortress• JRuby• Jython• JavaScript• Java FX

• All of the above already have Java implementations• Let's reuse scalable managed runtime investment• No need for Java bytecode (or extensions thereof)

Contribute!<fritzon@sun.com>

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