java modules using project jigsaw@jdk 9
TRANSCRIPT
Project Jigsaw@JDK 9Mauricio “Maltron” [email protected]/2016
Ever-growing and Indivisible Java Runtime
• Java runtime has always been growing in size.• Java 8 there was no way to install a subset of the JRE.• All Java installations were distributed with libraries for such
API’s as XML, SQL and Swing (whether you needed them or not).
• Significant for medium sized computing devices: Routers, TV-boxes, cars and other tiny nooks and crannies.
• Containers also gains new relevance on servers: Reducing an image’s footprint will reduce costs.
• Java 8: Compact Profiles
Roadmap for JDK 9
26/May/2016 Feature Complete11/August/2016 All Tests Run01/September/2016 Rampdown Start20/October/2016 Zero Bug Bounce01/December/2016 Rampdown Phase 226/January/2017 Final Release Candidate
http://openjdk.java.net/projects/jdk9/
23/Março/2017 General Availability
Class CountryClass State
Class City
firstfile.jar
depends
Class World
Java Today: No Encapsulation
Country c = new Country();State s = new State();City a = new City();
Class World
Java Today: Unexpressed Dependencies
?Problem will rise during runtime: NoClassDefFoundError
Country c = new Country();
Class CountryClass State
Class City
firstfile.jar
depends
Class World
Java Today: Shadowing
?Country c = new Country();
secondfile.jar
Class Country
depends
Class Territory
Class County
Class CountryClass State
Class City
firstfile.jar
secondfile.jar
Class CountryClass Territory
Class County
depends
depends
Country c = new Country();Class World
Java Today: Unexpressed Dependencies
?
Class Country1.0
firstfile.jar
secondfile.jar
Class Country2.0
depends
depends
Country c = new Country();Class World
Java Today: Version Collisions
?
Class World
Java Today: Startup Performance
Java runtime has loaded and JIT compiled all required classes.
Executes a linear scan of all JARs on the classpath
Identifying all occurrences of a specific annotation requires the inspection of all classes on the classpath
Project JigsawJSR 376: Java Platform Module System
Project Jigsaw
1Make the Java
SE Platform and the JDK, more easily scalable down to small
computing devices
2Improve security
and maintainability of Java SE Platform Implementations in
general, and the JDK in particular
3Enable improved
application performance
4Make it easier for
developers to construct and
maintain libraries and large
applications, for both Java SE and
EE Platforms.
[Modules] are named, self-describing program components consisting of code and data. A module must be able to contain Java classes and interfaces, as organized into packages, and also native code, in the form of dynamically-loaded libraries. A module’s data must be able to contain static resources files and user-editable configuration files.
Class CountryClass State
Class City
firstfile.jar
depends
Class World
Java 9: Strong Encapsulation
module com.example { exports com.example;} module-info
Country c = new Country();
City a = new City();State s = new State();
Class CountryClass State
Class City
firstfile.jar
depends
Country c = new Country();State s = new State();City a = new City();
Class World
Java 9: Improved Security and Maintainability
module com.example { exports com.example;} module-info
Critical code is now effectively hidden from code that does not need to use it. It also makes maintenance easier as a
module’s public API can more easily be kept small.
Java 9: Improved Performance
Java 9: Improved Performance
Existing optimization techniques can be used more effectively.
Java 9: Improved Performance
No distinction between JDK and JRE
Java 9: Scalable Platform
This will help maintain Java’s position as a key player for small devices as well as for containers
Java 9: Reliable Configuration
Ability to analyze these dependencies at compile-time, build-time and launch-time.
DEMO
