Universal Java

Using Java everywhere: server, desktop, mobile, IoT…

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About the Speaker

Philippe Riand– CTO of Trilog Group and Darwino– Former application development

chief architect for IBM Collaboration Services

– Chief architect, and inventor, of IBM Domino XPages

– Author of many OpenNTF projects

About Darwino

A distributed app-development platform for the rapid creation of collaborative applications (primarily Mobile, Cloud and IOT).

– Facilitates focus on the application logic;– Encapsulates services within comprehensive and portable APIs;– Incorporates an advanced JSON document store (atop of RDBMS),

both mobile and server;– Enables synchronization (aka, replication) from Enterprise systems

and provides a seamless offline capability;• Have a built-in, high fidelity, 2 way replication connector with IBM

Domino– Java-based, and uses familiar constructs, UI.

Agenda

• Why Java?• Java Pieces• Writing Portable Code with Java• Use Cases and Demos• Conclusion

Why Java?

Agenda

Why Java?

• As a language/platform– Java is the one of the most popular and used language– Java virtually runs on every platforms, albeit some differences

• Server, desktops, mobile, IOT– Java has the biggest ecosystem, set of libraries and development

tools– The JVM and runtime libraries can run several other languages

• For the enterprise– Scales well in term of team size– Libraries are Enterprise level code (Apache, Google Core…)– Strong security model– Error handling prevents crashes– Easy to find skills on the market

Java Popularity

http://www.codingdojo.com/blog/9-most-in-demand-programming-languages-of-2016/

http://spectrum.ieee.org/computing/software/the-2015-top-ten-programming-languages

http://redmonk.com/sogrady/2016/02/19/language-rankings-1-16/

Java PiecesOr

What is and what makes Java

Agenda

Java Pieces

Languages

ExecutionEnvironment

RuntimeLibrary

Java is, basically, made of 3 pieces that are intermingled

Source code

Class library JVM, Runtime Environment

Java Languages

• At the beginning, Java is a programming language– Defined by the JLS, Java Language Specification– Originally compiles to byte code, for the JVM– Depends on a minimum runtime library (ex: String, Class…)

• Many scripting languages are running on the Java platform– JavaScript (Nashorn), Ruby, Python…– Byte code has been enhanced to better support scripting languages

• General purposes/functional languages– Groovy, Scala, Kotlin, Clojure– Even Swift (RemObject Silver), C#...

• The languages targeting the Java platform can share the libraries and interact with each other

Main Execution Platform : Java JVM

• The stock Java compiler generates byte code (“.class” files) that will be then executed by the Java Virtual Machine. Class files can eventually be aggregated into archive files (.jar)

• The byte code can be interpreted or on the fly converted to machine code by the JVM (this is called “just in time compiler”)

• There are many JVM implementations available for a wide range of operating systems (IBM J9, Oracle VM, …), as well as many other open source implementations– Oracle’s is now open source through OpenJDK– IBM’s is being open sourced

Source Code

Class HelloWorld { … public static void main() { … }}

0A F5 89 19 … 7F 3C

Byte Code

Java HelloWorld

JVM

Execution Platform : Android VM

• Google introduced a new byte code format for Android called “dex” (Dalvik Executable), optimized for mobile devices

• It generates smaller files with byte code that can be processed faster by the JIT– ART, released with Android 5.0 also now

pre-compiles the classes (AOT)• The existing compiled libraries can be

used as is• Has side effects with dynamic

languages, like Groovy, or Java libraries containing resources

Source Code

Class HelloWorld { … public static void main() { … }}

0A F5 89 19 … 7F 3C

Byte Code

Adb shell … HelloWorld

Dalvik/ART VM

07 6A 46 … 8F 33 15 AC

Dalvik JAR

Execution Platform: Transpilers and AOT

• Transpilers– Java transpilers convert java source code to another language

• Google GWT converts Java to JavaScript• J2OBJC converts Java to Objective “C”• JUniversal… but abandoned by Microsoft

– Java class transpilers converts .class file to source code• J2C, Haxe…

• Ahead of Time compilers – AOT– AOT compilers statically generate machine code from either the

source code, or even better the compiled “.class” files• Excelsior JET (Desktop: Windows, OSX & Linux)• Multi OS Engine (MOE)• Avian, RoboVM, GCJ, XMLVM…

Java Runtime Libraries

• Java comes with a set of classes ready to use, provided by a runtime library implementation.– Some are tied to the language (ex: String, Class, …). These classes

must be available in order to run a Java program.– Some are just portable services (ex: java.io.*, java.net.*...). They are

not strictly part of the language specification, and may vary between implementations.

– Some can be platform specific, or even JVM/target environment specific (com.ibm.*, …)

• The use of a runtime library matters a lot as it defines the available APIs and their behaviors– Oracle JVM, Android… have different classes, or different

implementations of the same classes

The Landscape of Java Runtime Libraries

Apache Harmony

OpenJDK

Android Dalvik

Android ART

ART Next

GNU Classpath

Environment specific

- GWT, J2OBJC- CodenameOne- Avian- JUniversal- …

ART Next

- GJC- Other OS projects

- Oracle Hotspot- IBM J9

Sun JDK

- Android 1-4

- Android 5-6

- Android 7+

Writing Portable Java

Agenda

Writing Portable Java

• There are two kinds of code that must be separated– The code that is platform independent (ex: business logic)

• Executed as is on all the target platforms• Should only use common language and library characteristics

– The one that depends on the platform (ex: mobile UI)• One set of code per platform• That should be well isolated into specific projects

=> A typical portable application is made of several projects– Shared code– Target platform specific projects (or shell)

Native UIs Strategies

• Strategies for portable native APIs– The minimum common denominator

• AWT– UI frameworks written in Java

• Swing, JavaFX• CodenameOne, Nuvos, …

– Advanced wrappers with extensions to supplement missing native implementations

• SWT• Directly use the native, not portable APIs

– Cocoa, Win32, Android, Qt…• Using direct API calls: JNI, JNA• Using advanced native API bridges: NAT/J, Bro

Use Case #1Client & Server Reusable Code

Agenda

Trilog’s ProjExec: the Gantt Component

• Projects are accessed through different Pages/Component/APIs– Have an existing Java Applet Gantt

• Need a new JavaScript implementation as Java Applet are deprecated– Need a REST APIs exposing the business objects to remote clients

• Actions on a project carry a lot of complex business logic– To provide the best user experience, the Gantt UI Component should

execute the business logic locally– The same business logic should run on the server as well (REST APIs

and data integrity/security)• We need a single implementation that runs everywhere

– Existing code is in the Java Applet– Don’t want to rewrite it in JavaScript (cost, server technology, team

scalability…)

Trilog’s ProjExec: the Gantt Component

• Solution:– The business logic is written in Java and well isolated in its own

project• Use the common platform characteristics• No external dependency

– Executes natively on the server and Applet, while it is transpiled to JavaScript using GWT

• The exact same code is executed on both client and server– The browser UI is native HTML/Javascript

• Actually, built using GWT and GXT, but straight HTML/JS can be used– Opens the door to a pure mobile implementation– Close to what Google does with ‘Inbox’

Trilog’s ProjExec: Gantt Component

Trilog’s ProjExec: the Gantt Component

• Lessons learned– We needed a few wrappers that abstract runtime specific APIs

• JSON, Timezone…– Integrates well with a maven based build– Share the unit tests between the implementations– Java VM & transpiled JavaScript can have slight decimal

calculation differences– GWT 2.8 features a nice new JSInterop capability to be

leveraged

Use Case #2Cross Platform Web UI

Agenda

Demo of a Multi Platform Web Hybrid Application

• Demo application targeting web browsers, Mobile and Desktop– Application business logic shared, all in Java– Core runtime libraries, including third party, all in Java– Web technologies used for the application UI– Mixed-in native UI for standard components (ex: settings dialog)

Use Case #3Multi-Platform Native UI

Agenda

Pure Native UIs in Java

• Available Solutions– CodenameOne

• Commercial and OpenSource product (GPL)• Limited runtime library, cumbersome build and debugging process, no

interface builder…– RoboVM

• Very efficient solution but no longer a supported product (killed by MS)• There is a maintained branch on Github, mostly to support LibGDX:

https://github.com/MobiDevelop/robovm– 1 Yr old code based, with missing features (debugger, interface builder…)– We contributed some code (maven integration…)

– Multi OS Engine (aka Intel INDE or Intel MOE)• Acquired by Intel in 2015 from Migeran• Now fully open source, under the Apache 2.0 license

– https://github.com/multi-os-engine, https://multi-os-engine.org/

Open Source Multi OS Engine

• Features– Targets iOS & Android, more to come!– AOT & Android ART VM interpreter– On Device Debugging Support– Android studio integration– Java to Native Binding NAT/J

• Automatic Native Binding Generation• Access Objective-C Language Features in Java

– Android & iOS Interface Builder Integration• On the work:

– Eclipse integration– Maven integration

MOE Demo

Conclusion

Agenda

Other Areas for Java

• Java is part of IoT’s future– Samsung ARTIK

• IDE powered by Eclipse Che• Extensive Java SDK

– Intel MOE makes it possible to target IoT• Easy for any POSIX compliant OS

– Google Brillo, Fluschia• Highly portable to other systems

– Java transpilers targeting IoT devices• C++ transpiler – to be released to darwino.org (OpenNTF)

• And Games…– LibGDX– jMonkeyEngine

Multi-platform Java: What Technologies to Use?

• Server– JVM

• Desktop– JVM– AOT (MOE, Jet, RoboVM)

• Android– Native Dalvik/ART VMs

• iOS– AOT (MOE, RoboVM, Avian…)– Transpiler (j2objc)

• HTML– GWT (JSweet…)

• Oracle: Mobile OpenJDK 9 with “zero interpreter” for iOS. AOT might be in progress

This is The end