Java SE Keynote
Java platform is now targeting:
- productivity
- performance
- universality
- modularity
- integration
Java language evolution will be:
- for generics: declarations like:
HashMap<String, List<String>> map = new HashMap<String, List<String>>();will become:HashMap<String, List<String>> map = new HashMap<>(); - lambada expressions will be added (JDK 8)
- type reification: primitive type will be used as generics
- module will be added: based on descriptor (module-info.java) and manage by JMOD (integration with maven and its repositories)
- module will be able to be package as RPM, JAR or DEB or directly managed by JMOD
Java evolution has been planned until 2030.
For the roadmap:
- Java 7: end of july 2011 (project coin, fork/join framework)
- Java 8: end of 2012
Java Persistence 2.0
JPA 2.0 brings some news:
- Criteria API
- pessimistic lock
- metamodel API
- standardize configuration
- collections of basic types
Basic types collections:
- @ElementCollection: this collection must be stored as an elmeent collection
- @CollectionTable(...): specify the table name
- @Colcumn(...): specify the collection column name
Embadable objects:
- multi level (@AttributeOverride)
- relationship (@AssociationOverride, @JoinTable)
Persistence order:
- implemented by provider as an additional column (@OrderColumn)
- in case of legacy use @OrderBy to use existing schema
Maps usage:
- key: basic type, embeddable, entity
- value: basic type, embeddable, entity
JPQL:
- conditional expression: CASE ... THEN .. (usefull with map)
- restriction on type TYPE(e) IN (...) (usefull for inheritance)
Criteria API: support object and strinf literals
- CriteriaQuery: query description
- CriteriaBuilder: criteria query objects factory
- How to express: select c from Customer
CriteriaQuery cq = criteriaBuilder.createQuery(Customer.Class);
Root root = cq.from(Customer.class);
cq.select(root);
Metamodel: abstract schema model.
Pessemistic lock: specify mode as properties.
Second level cache API: use of @Cacheable on properties
Standardized configuration by providing a set of default properties.
Validation: automatic validation for PrePersist, PreUpdate and PreRemove.
The Next Big JVM Language
Actually, languages challenge Java by providing more features and different expression ways (have a look to Stephen Colebourn).
What Java has done right:
- simplify C++ migration
- take old ideas but JVM make them popular (garbage collector for example)
What Java has done wrong:
- Checked exception: how to ignored them?
- primitives: split type system
- arrays: split type system and expose JVM future
- monitors: unsafe effects, difficult to optimize
- static: cannot be override, hurt concurrency
- method overloading: complexity for compiler and for programmer
- generics: too complex, background compatibility result in erasure
The New Big JVM Language should be:
- like C syntax
- multi paradigm: object oriented and functional
- type system: static typing
- easy reflection
- have properties
- have closure in language core
- a better null handling (avoiding NullPointerException and long and borring debugging)
- thread not exposed
- have modules
- good tooling (make tooling esay to build)
- extensible (combination of language feature)
- not verbose
No JVM languages fullfil these criteria, so, perhaps it is time for a none backward compatible version of Java: Java 9?
Project Lambda: To Multicore and Beyond
The based of Lambda project is SAM types: interfaces or abstract classes with a single abstract method.
Closure take the following syntax:
#{Person.getLastName()}
Collection framework will be adapted to provides facilities based on closure, such as filtering, sorting, etc...
New key words will be added to define immutable classes and their properties:
value class ImmutableClass {
properties String lastname;
}
Actually, modifying an interface results to breaking API compatibility. With Lambda, it will be possible to add method with default behavior.
Spring 3.1 - Themes and Trends
Spring 3.0 brings:
- annotated component model
- expression language
- REST support
- Portlet 2.0
- support Java EE 6 (JPA 2)
- custom annotation
- include JavaConfig (configuration classes)
- @Value (use of value express with EL)
- model validation @Valid on parameters
- type conversion @DateTimeFormat(iso=ISO.DATE)
- annotation scheduling: @Scheduled
Spring 3.1 will provide:
- environment profiles
- activated in command line by: -DspringProfile=env
- provides environment abstraction as an API
- custom placeholder resolution
- java based configuration: @Configuration on class
- cache abstraction
- EhCache support (important for cloud)
- support for Gemfire, Coherence
- annotation @Cacheable
- cache could be conditional
- @CacheEvict to avoid caching
- new namespace declaration
- conversation management:
- HttpSession ++
- association with browser and tabs
- foundation for WebFlow 3
- Groovy will be used as template engine
- c: namespace for constructor arguments
- Roadmap:
- M1 in december
- 3.1 GA march/april 2011
HTML 5 Websockets: A New World of Limitless, Live, and Wickedly Cool Web Applications
Actually, HTTP is not full duplex, so, Websockets brings full duplex to web.
It is implemented as a Javascript API that uses IETF protocol, but is still compatible with HTTP. The idea is not to replace HTTP.
Websocket allowed cross origin, secured and unsecured communication in standard.
It is supported by browsers:
- Chrome 4.0+
- Safari 5.0, iOS 4
- Firefox 4 beta
- to check compatibility, go to Websocket web site
Beyond the scene, Websocket allows:
- connection reuse
- extends client server protocol (available in JS API)
Visage Android Workshop
Visage is a dynamic UI language inspired by Flex and JavaFX for different target, and especially, for Android.It is declarative, brings data binding, provides closure to implements triggers and brings null safety.
Compilation is divided in two phases:
- Visage to Java bytecode
- Bytecode to Dalvik
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