GWT, CDI & JAX-RS A match made in heaven Heiko Braun - - PowerPoint PPT Presentation

GWT, CDI & JAX-RS

“A match made in heaven”

Heiko Braun <hbraun@redhat.com>

About me

• Heiko Braun
• Senior Software Engineer JBoss / Red Hat
• 4 years JBoss, 12 years industry
• Focus on SOA, BPM, GWT
• Contributor:

JBossWS, jBPM, Riftsaw, Errai, SAM, Savarra > http://jboss.org

Topics

• GWT ecosystem
• Integrating with CDI
• When to use JAX-RPC

GWT ecosystem

GWT: Strong client side

• GWT SDK: Tools & API to build Ajax clients &

frameworks

• Integration capabilities:
• GWT RPC
• XHR (Request Builder)
• Data formats: JSON, XML
• Rich set of widget libraries:
• Mosaic, Smart GWT, etc

GWT: Weak server side

• Service implementation choice:
• rely on GWT RPC
• or handle the low level protocol manually
• Existing domain & component model?
• Adapters, DTO’s, parallel hierarchy, etc
• TX, Security, etc
• A lot of boilerplate needs to be written

Backend implementation

• ptions

Java EE choices

• CDI: Context and dependency injection for

the EE platform (http://jcp.org/en/jsr/summary?id=299)

• Java API for RESTful web services

(http://jcp.org/en/jsr/detail?id=311)

• Both part of EE 6

Relation to Errai

• CDI integration build on Errai

(http://jboss.org/errai)

• Integration is actually an extension to Errai

and vice versa

• Knowledge about Errai Message Bus helpful,

but not mandatory

GWT & CDI

GWT & CDI goals

• Similar to GWT
• RPC:
• re-use domain model
• transparent wire protocol (serialization)
• In addition to GWT
• RPC:
• Bypass the servlet tier (merely transport)
• Deep integration with EE component model
• Richer programming model & reduction of boiler

plate

CDI Concepts

• Portable Extensions
• Integration point when container bootstraps
• Create beans, annotation processing, meta data

modifications

• Scope & Lifecycle
• ApplicationScoped, RequestScoped, ConversationScoped
• Bean context & reference
• Lookup and instance (reference) creation

12

GWT & CDI Samples

Using Pub/Sub

• Most low level use cases

(Errai Bus, Pub/Sub)

• Similar to MessageDriven

Bean (actual maps to it)

• Service implementation

fully managed by CDI container

• Message Bus instance

injected

CDI Component GWT Client

14

Exposing RPC endpoints

• Exposes a typed

interface

• Similar to EJB Session

beans (maps to it)

• RPC style, type safe

client API

CDI Component Remote interface GWT Client

15

Working with CDI events

• Bi-directional event

exchange

• Discriminate on:
• Event Type
• Qualifier Annotations
• Exposes high level CDI

client API

• Integrate with default and

custom CDI events

CDI Component GWT Client

16

When to integrate with CDI

• Benefits of Java EE 6 and GWT as an

alternative view layer technology

• Concise Java component model
• Tool chain: GWT, EJB, CDI, JPA, JCA, JMS

17

GWT & JAX-RPC

GWT & JAX-RPC goals

• RESTful web services:
• RESTful API: open to non-java clients
• Intermediaries: proxies, gateways, firewalls
• [...] (See other Jazoon talks on this topic)
• Expose low level protocol with a decent API
• Directly expose XML, HTML from other resources
• BIRT reporting (mashup, iframe)
• Use of XML documents
• Integrate with XHR (RequestBuilder)
• Reuse domain model (serialization)

JAX-RPC Concepts

@Path("/customerservice/")

@Produces("application/xml") public class CustomerService { @GET @Path("/customers/{id}") @Produces("application/json") public Customer getCustomer(@PathParam("id") String id) { ...... } @PUT @Path("/customers/{id}") @Consumes("application/xml") public Response updateCustomer(@PathParam("id") Long id, Customer customer) { ...... } @POST @Path("/customers") public Response addCustomer(Customer customer) { ...... } @DELETE @Path("/customers/{id}/") public Response deleteCustomer(@PathParam("id") String id) { ...... } }

GWT & JAX-RPC samples

Request a JAX-RPC resource

GWT Client Server Resource

Conclusion

• CDI integration probably most reasonable choice for

within EE 6 environments

• Integration & boilerplate missing: Errai [1] to the rescue
• JAX-RPC is more open, but very low level.

Still better then writing your own servlet code

• Remember:

You can mix and match JAX-RPC and CDI within the same components (at least on JBoss 6)

[1] http://anonsvn.jboss.org/repos/errai/projects/weld-integration/trunk/

Q&A

> http://jboss.org/errai > http://errai-blog.blogspot.com/

Appendix A: Errai Message Bus

Errai Basics

• Backbone to application

design

• Federated architecture
• Asynchronous & bi-

directional

• Supports POJO

serialization

• Common shared API
• Supports OpenHUB spec
• HTTP + NIO

Errai API

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