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Java EE:Extendable and Functional

David BlevinsTomitribe

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Talk Overview

• Part 1: Extensibility• CDI Scopes• Connectors• Java EE 6-7

• Part 2: Functions• New API Opportunities with Java 8• Killing annotations• Shift from Declarative to Programmatic• Java EE 8?

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Part 1: ExtendableCDI Scopes

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Background

• EJB and CDI Alignment• EJB slowly being deprecated• Functionality moving to CDI• CDI significantly more extendable

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CDI and EJB Under the Covers

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PProxy (Fake)

Proxy (Fake)

Interceptors

Decorators

Instance (Real)

Security

Transaction

Interceptors

Decorators

Instance (Real)

1. Resolution

2. Services

3. Invocation

(Pool)1. Resolution

2. Services

3. Invocation

(Context/Scope)

CDI 1.0 EJB 3.1

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PProxy (Fake)

Proxy (Fake)

Security

Transaction

Interceptors

Decorators

Instance (Real)

1. Resolution

2. Services

3. Invocation

(Pool)1. Resolution

2. Services

3. Invocation

(Context/Scope)

CDI 1.1 EJB 3.2

Transaction

Interceptors

Decorators

Instance (Real)

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EJB/CDI Lifecycle Lineup

• @Singleton

• same as CDI @ApplicationScoped

• @Stateful

• applies to any CDI Scope, not just @SessionScoped

• @Stateless

• no CDI equivalent

• @RequestScoped sort of close(ish)

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Implementing a Scope

• Create a new Scope Annotation

• Create an implementation of Context

• Register the Scope and Context via an Extension

• Mark the boundaries

• Logical concept

• Always different

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Custom Scope Examples

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http://tomitribe.io/projects/microscoped

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Common Mistakes you will make

• Not putting a beans.xml in your app (Java EE 6)• No CDI for you!

• Not understanding @Typed• Psst, think @Local from EJB• Bites you when using @Produces

• Not understanding what Dependent and NormalScope• Dependent == plain object• NormalScoped == proxied object• Bites you when creating custom scopes

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Part 1: ExtendableConnectors

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Inbound Connectors(aka MDBs)

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The following are all false

• MDBs are for JMS

• MDBs must be asynchronous

• A MessageListener interface has one method which returns ‘void’

• MDBs are always pooled

• MDBs are stateless

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JMS MDB in Java EE 7

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Title Text

• Body Level One• Body Level Two• Body Level Three• Body Level Four• Body Level Five

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Title Text

• Body Level One• Body Level Two• Body Level Three• Body Level Four• Body Level Five

Bad Configuration

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Title Text

• Body Level One• Body Level Two• Body Level Three• Body Level Four• Body Level Five

Boiler Plate

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Title Text

• Body Level One• Body Level Two• Body Level Three• Body Level Four• Body Level Five

Only Useful Line of Code

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JMS MDB in Java EE 8

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Oh yeah.

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Custom Connector Examples

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https://tomitribe.io/projects/chatterbox

https://tomitribe.io/projects/sheldon

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Part 2: Functional(Ideas for the Future)

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Eras of Java EE

• 1998 (start)• 2001 (strong) • 2006 (start)

• 2009 (strong)• 2014* (start)

• ???? (strong)

XML Annotation Lambda

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Opportunity for Impact

• From Declarative to Programmatic• From Component-side to Caller-side• Large decrease in annotation and class overhead• Logic is mobileImpact of Opportunity• Potential Growth in mixed container and “API” code• Lifecycle compromises might need to be made• Will take time and effort (join in!)

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Thank You!