Download - Gwt cdi jaxrs_hbraun
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 options
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
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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
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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
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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
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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
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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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