EJB and CDI - Alignment and Strategy

EJB and CDI
Alignment and Strategy
Linda DeMichiel
Java EE Specification Lead
Oracle
Java Day Tokyo 2015
April 8, 2015
Copyright © 2015, Oracle and/or its affiliates. All rights reserved. |

Safe Harbor Statement
The following is intended to outline our general product direction. It is intended for
information purposes only, and may not be incorporated into any contract. It is not a
commitment to deliver any material, code, or functionality, and should not be relied upon
in making purchasing decisions. The development, release, and timing of any features or
functionality described for Oracle’s products remains at the sole discretion of Oracle.
4

Program Agenda
EJB – History, Goals, Evolution
CDI– History, Goals, Evolution
Advantages/disadvantages – when to use EJB/CDI
Java EE – Managed Bean Alignment
What is our strategy for the future
1
2
3
4
5
5

EJB
• EJB 1.0 (begun 1996)
– Origins in TP monitors and component-based systems (e.g. Microsoft MTS)
– Designed for remote access and coarse-grained components
• EJB 1.1 (J2EE 1.2)
– First "real" EJB
• EJB 2.0 (J2EE 1.3)
– Updated Entity Beans; EJB QL; Message-driven Beans; IIOP Interoperability
• EJB 2.1 (J2EE 1.4)
– Web services support; Timer service
Some Background and History
6

EJB
• EJB 3.0 (Java EE 5)
– First "modern" EJB – Theme is "Ease of Development"
– Annotations; resource injection; simple interfaces; Java Persistence API; interceptors
– No-interface view; asynchronous methods; singletons; EJB Lite; Embedded EJB
– Interceptors separated into own spec; JPA separated into own JSR
– EJB Entity Beans and JAX-RPC now optional
7

EJB Today
• EJBs are POJOs
• Container provides services for ease-of-development
– Injection
– Transactions (declarative with defaults or programmatic)
– Security (declarative with defaults or programmatic)
– Thread management; synchronization; async support
– Timed notifications (declarative or programmatic)
– Integration with JMS, Web Services, IIOP-based clients and services
8

Program Agenda
1
2
3
4
5
9

CDI
• CDI 1.0 (Java EE 6)
– Original goal: direct JSF and EJB integration
– Dependency injection with typed injection points; typesafe resolution
– Annotations, qualifiers, stereotypes for strong typing
– Scopes, contexts for automatic bean lifecycle management
– Producers
– Interceptor bindings; decorators
– Events and observers
– Rich SPI for portable extensions
10

CDI
• CDI 1.1 (Java EE 7)
– Implicit bean archives
– Globally enabled interceptors, decorators, alternatives (with @Priority)
– JTA transactional interceptors; @AroundConstruct interceptors
– Enhancements to SPI and portable extensions
11

CDI Today
• Managed Bean POJOs are central
– @Named qualifier allows direct use in JSF, EL, …
• Container provides services
– Type-safe injection
– Lifecycle management; contexts; scopes; lifecycle callbacks
– Event firing and delivery
– Producers, Alternatives to configure available beans
– Extensible model and rich SPI
12

Program Agenda
1
2
3
4
5
13

CDI Advantages
• Annotation-based programming model; stereotypes
• Type-safe injection, interceptors, decorators
• Context management, scopes, conversations
• Events and observers
• Producers and disposers
• Extensibility
– Custom scopes; programmatically defined beans; etc.
Higher level of abstraction
What does CDI give you that EJB alone does not?
14

CDI Advantages
• Automatic context and lifecycle management remove/pooling
• Events+observers callbacks
• Conversations
• Metalevel programming / extensibility
Higher level of abstraction vs EJB
15

EJB Advantages
• Remote access
– RMI / CORBA
– Web Services
• MDBs / JMS
• Timers; scheduled events
• Asynchronous methods
• Security intergration
• JPA integration; container-managed extended persistence context
• Locking for concurrent access
What does EJB give you that CDI does not?
16

EJB Advantages
• EJBs (session beans) are CDI managed beans
– They have all the benefits of CDI
– Stateless session beans – @Dependent scope
– Stateful session beans – any scope
– Singleton session beans – @ApplicationScoped
– However, need to use @Inject, not @EJB to acquire
• Converse is not true
– CDI beans are not EJBs
– However: We are moving EJB benefits into CDI
What else does EJB give you?
17

Program Agenda
1
2
3
4
5
18

CDI and EJB: Bridging the Gap in Java EE
• @ManagedBean
• Managed Bean spec, introduced in Java EE 6
– Identified commonalities among different components as "managed beans"
– Identified points for extension
• "Managed Bean Alignment" was an important theme of Java EE 7
– Generalize use of injection, interceptors, new scopes
19

Managed Beans – Java EE 6
20
MATRIX1
Java EE 6
Contextual Support
CDI
injection
into
them
Support
Java EE
Resource
injection
into
them
Injectable
with
@Inject
Injectable
with
@Resource,
@EJB, …
(EE-
defined)
Support
CDI
interceptors
Support EE
interceptors
Support
Decorators
Support
Observer
methods
Can
fire
events
Support
Producer
methods
Can have
Qualifiers
Can
have
Scope
Support
CDI
Constructor
injection
Support
Timers
CDI managed
beans (non-EJBs)
Y Y Y Y Y Y Y(1) Y Y Y Y Y Y Y
Session beans
(CDI-enabled
behavior via
@Inject)
Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y
Java EE
@ManagedBean
beans (CDI-
enabled behavior
via @Inject)
Y Y Y Y Y Y Y Y Y Y Y Y Y Y
Session beans
obtained via
@EJB or JNDI
lookup (with CDI
enabled)
Y Y Y Y Y Y
Java EE
@ManagedBeans
beans obtained
via @Resource or
JNDI lookup
(with CDI
enabled)
Y Y Y Y Y
MDBs Y Y Y Y Y
JAX-RS Resource
classes
Y Y Y
Servlets Y Y Y
Servlet filters,
listeners
Y Y Y
Other Java EE
component
classes (Table EE.
5-1)
Y Y Y
JPA entities
JPA entity
listeners
Y(4) Y
Interceptors Y Y Y
Decorators Y Y Y
Producer
methods
Y(3) Y(5) Y(5) Y Y (2)(3) Y(2)
Producer fields Y(2) Y(2)
Disposer
methods
Y(3) Y(5) Y(5) Y Y(3)
Observer
methods
Y(3) Y(5) Y(5) Y Y(3)

CDI and EJB: Bridging the Gap in Java EE 7
• CDI is enabled by default in "implicit bean archives"
• Use of CDI bean-defining annotations results in implicit bean archives
– @SessionScoped, @Dependent, …
– Bean archives include library jars, EJB jars, WEB-INF classes, …
– No beans.xml required
Enabling CDI by Default
21

• CDI injection applies to all Java EE components when CDI is enabled
• Java EE components support resource injection + CDI injection
– Support for constructor injection added as well
• CDI beans support CDI injection + resource injection
• CDI producers can "transform" resource injection into CDI injection, making
it strongly typed
@Produces @Resource(lookup="java:global/env/jdbc/CustomerDatasource")
@CustomerDatabase DataSource customerDatabase;
Injection
22

• CDI interceptor-binding interceptors apply to all Java EE components when
CDI is enabled
• EJBs support "EJB interceptors" + CDI interceptor-binding interceptors
• CDI beans support CDI interceptor-binding interceptors + "EJB
interceptors"
• Java EE components also support both
Interceptors
23

JTA Transactional Interceptors
@Inherited
@InterceptorBinding
@Target({TYPE, METHOD}) @Retention(RUNTIME)
public @interface Transactional {
TxType value() default TxType.REQUIRED;
Class[] rollbackOn() default{};
Class[] dontRollbackOn() default{};
}
@Transactional(rollbackOn={SQLException.class},
dontRollbackOn={SQLWarning.class})
public class ShoppingCart {...}
Generalization of Container-managed Transactions (Java EE 7)
24

Bean Validation Interceptors
@Stateless
public class OrderService {
...
@ValidOrder
public Order placeOrder(
@NotNull String productName,
@Max(10) int quantity,
@NotNull String customerName,
@Address String customerAddress) {
...
}
}
Method-level Validation (Bean Validation 1.1, Java EE 7)
25

• CDI Scopes are extensible
– @TransactionScope
• Defined in JTA 1.2
• Used by JMS 2.0
– @FlowScoped (JSF 2.2)
– WebSocket expected to define scope for WebSocket endpoints in Java EE 8
Scopes
26

Managed Beans – Java EE 7
27
MATRIX
Java EE 7
Contextual Support
CDI
injection
into
them
Support
Java EE
Resource
injection
into
them
Injectable
with
@Inject
Injectable
with
@Resource,
@EJB, …
(EE-
defined)
Support
CDI
interceptors
Support EE
interceptors
(1)
Support
Decorators
Support
Observer
methods
Can
fire
events
Support
Producer
methods
Can have
Qualifiers
Can
have
Scope
Support
CDI
Constructor
injection
Support
Timers
CDI managed
beans (non-EJBs)
Session beans
(CDI-enabled
behavior via
@Inject)
Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y
Java EE
@ManagedBean
beans (CDI-
enabled behavior
via @Inject)
Session beans
obtained via
@EJB or JNDI
lookup (with CDI
enabled)
Y Y Y Y Y Y Y Y Y
Java EE
@ManagedBeans
beans obtained
via @Resource or
JNDI lookup
(with CDI
enabled)
Y Y Y Y Y Y Y Y
MDBs Y Y Y(6) Y Y Y Y Y
JAX-RS Resource
classes
Y Y Y(6) Y Y Y Y Y
Servlets Y Y Y(6) Y Y Y Y Y
Servlet filters,
listeners
Y Y Y(6) Y Y Y Y Y
Other Java EE
component
classes (Table EE.
5-1)
Y Y Y(6) Y Y Y Y Y
JPA entities Y(6)
JPA entity
listeners (4)
Y Y(6) Y Y Y Y Y
Interceptors Y Y Y(6) Y Y
Decorators Y Y Y Y
Producer
methods
Y(3) Y(5) Y(5) Y Y (2)(3) Y(2)
Producer fields Y(2) Y(2)
Disposer
methods
Y(3) Y(5) Y(5) Y Y(3)
Observer
methods
Y(3) Y(5) Y(5) Y Y(3)

Program Agenda
1
2
3
4
5
28

• Java EE 8 continues the theme of Managed-Bean Alignment
• Container-managed security: authorization
• Message-driven beans
Expanded use of EJB Container Services
29

Proposed: Authorization via Security Interceptors
@IsAuthorized("hasRoles('Manager') && schedule.officeHrs")
public void transferFunds() {...}
@IsAuthorized("hasRoles('Manager') && hasAttribute('directReports', employee.id)")
public double getSalary(int employeeId) {...}
@IsAuthorized(ruleSourceName="java:app/payrollAuthRules", rule="report")
public void displayReport() {...};
Java EE Security 1.0 (Java EE 8)
30

Message-driven Beans
• Alternative to EJB message-driven beans
• Usable by any CDI managed bean
• Simpler JMS-specific annotations
• No need for MessageListener implementation
JMS 2.1: New API to receive messages asynchronously (Java EE 8)
31

Message-driven Beans
@MessageDriven(activationConfig = {
@ActivationConfigProperty(propertyName="connectionFactoryLookup",
propertyValue="jms/myCF"),
@ActivationConfigProperty(propertyName="destinationLookup",
propertyValue="jms/myQueue"),
@ActivationConfigProperty(propertyName="destinationType",
propertyValue="javax.jms/Queue")}
public class MyMDB implements MessageListener {
public void onMessage(Message message) {
// extract message body
String body = message.getBody(String.class));
// process message body
}
}
EJB MDBs Today (Java EE 7)
32

Proposed: Message-driven Beans
@RequestScoped
public class MyListenerBean {
@JMSListener(destinationLookup="jms/myQueue")
@Transactional
public void myCallback(Message message) {
...
}
}
JMS 2.1 Tomorrow: Allow any Java EE bean to be a listener (Java EE 8)
33

Bridging the Gap
• JAX-RS Injection alignment
• Parameter injection
• Scope for WebSocket endpoints
• Extension of Timer Service and Timer notifications (@Schedule)
• …
Other Areas of Alignment
34

Some Gaps Remain
• Java EE components are CDI managed beans
– They can be injected with @Inject
– But, Java EE components other than session beans lose their Java EE
"componentness"
– E.g., you can inject a servlet into a managed bean, but the injected instance won't still
service web requests
35

Summary
• Java EE 6
– Interceptors
• Java EE 7
– Container-managed transactions transactional interceptors
• Java EE 8
– Container-managed authorization security interceptors
– Message-driven beans simplified messaging with CDI-based MDBs
• Java EE 9
– Timer Service (?)
– Timed Events (?)
– … (?)
EJB Features made more broadly available through CDI
36

What is the Future of EJB?
• Part of EJB becoming Optional
– EJB Entity Beans, EJB QL
• Optional as of Java EE 7; superseded by JPA
– Support for JAX-RPC
• Optional as of Java EE 7; superseded by JAX-WS
– IIOP Interoperability ??
• Java EE 8 Experts will decide on "Proposed Optional" status
– Remote interfaces ??
• Java EE 8 Experts will decide on "Proposed Optional" status
– Optionality process is slow
• Takes 2 Java EE Platform release cycles
37

What is the Future of EJB?
• Important EJB features are being made more broadly available
– Interceptors, container-managed txs and security, MDBs, …
– Availability is through mechanisms of CDI
• Will EJB still be relevant ?
• EJB's long-term future depends on the future of remaining features
– Remote access (RMI, Web Services)
– @Schedule'd events and Timer Service
– Singletons - @Startup; @DependsOn; container-managed concurrency
– Asynchronous methods
– Integration with JPA
38

How You Can Influence the Discussion
• Adopt a JSR
– http://glassfish.org/adoptajsr
• Join an Expert Group project
– http://javaee-spec.java.net
– https://java.net/projects/javaee-spec/pages/Specifications
• The Aquarium
– http://blogs.oracle.com/theaquarium
• Java EE 8 Reference Implementation
– http://glassfish.org
39

Safe Harbor Statement
The preceding is intended to outline our general product direction. It is intended for
information purposes only, and may not be incorporated into any contract. It is not a
commitment to deliver any material, code, or functionality, and should not be relied upon
in making purchasing decisions. The development, release, and timing of any features or
functionality described for Oracle’s products remains at the sole discretion of Oracle.
40

EJB and CDI - Alignment and Strategy

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