JavaCro'14 - Consuming Java EE Backends in Desktop, Web, and Mobile Frontends – Geertjan Wielenga

Copyright © 2012, Oracle and/or its affiliates. All rights reserved. Public1
Consuming Java EE
in Desktop, Web, and Mobile Frontends
Geertjan Wielenga
Oracle Developer Tools
geertjan.wielenga@oracle.com
@geertjanw

Copyright © 2012, Oracle and/or its affiliates. All rights reserved. Public2 Copyright © 2012, Oracle and/or its affiliates. All rights reserved. Public
Agenda  JavaScript/HTML5 Rich Client
Landscape
 Java EE 7
 Java EE + JavaScript
 Tools and Technologies
 Demos

JavaScript/HTML5 Rich Clients Landscape
 The thin client vs. rich client debate is pretty old…
» Thin Client
- All processing on server
- Round tripping to server
- Delays…
» Thin Client Rich Client
» - Complex, dynamic
» - Feature-rich UI
» - Access local resources

 Server side frameworks have ruled for a while
– Everything on the server
 Spring / Hibernate
 JSF
 Struts
 Tapestry
 AJAX is a mild shift to the client, “best of both worlds approach”
– Asynchronous partial page refresh solutions
 PrimeFaces
 Wicket
 GWT
 Vaadin

Demo: PrimeFaces, Java EE, and Maven

 Rich clients powered by JS/HTML appear to be making a comeback
– Improving JavaScript engines
 V8
 *Monkey
 Nashorn
– Better tools
 jQuery
 MV* Frameworks
 Chrome, FireFox
– Standards advancement
 CSS3
 HTML5
 WebSocket

Perhaps Not A Slam Dunk?
 Richer clients clearly better at some things
– Highly dynamic, interactive interfaces
– Complex, feature-rich UIs
– “Single page applications” (“Applets” )
 But perhaps not a panacea
– Heavily form/workflow driven applications
– Server-side rendering still a better bet for performance/reliability?
– JavaScript/HTML development is not without it’s pains…
– Server-side frameworks are a strong incumbent
 Co-existence in the short and long term?
– Islands of rich client functionality within server-centric UIs?
– Different strokes for different folks?

My Big Fat Rich-Client Architecture
 Very similar to client/server architecture of lore
– Client responsible for UI rendering, basic input validation, logic and state
– Server responsible for business logic, domain model, persistence
– Web/HTTP is glue that connects client and server
 Typical communication protocols
– REST for majority of cases
– WebSocket when full-duplex communication is needed
– JavaScript tools support REST well, but not WebSocket (yet)
 The typical (ideal?) data interchange format is JSON
 Java EE is a great server-side platform for this architecture…

Java EE + JavaScript
EJB 3
Servlet
CDI
JPA
JAX-RS
BeanValidation
Java API for
WebSocket
Java API for
JSON
JMS JTA
JavaScript/HTML5
JAXB
JCA

JAX-RS
 REST development API for Java
 Server and client
 Annotation based, declarative
– @Path, @GET, @POST, @PUT, @DELETE, @PathParam,
@QueryParam, @Produces, @Consumes
 Pluggable and extensible
– Providers, filters, interceptors

JAX-RS Example
@Path("/atm/{cardId}")
public class AtmService {
@GET
@Path("/balance")
@Produces("text/plain")
public String balance(
@PathParam("cardId") String card,
@QueryParam("pin") String pin) {
return Double.toString(getBalance(card, pin));
}
...

Java API for WebSocket
 High level declarative API for WebSocket
 Both client and server-side
 Small, powerful API
– @ServerEndpoint, @OnOpen, @OnClose, @OnMessage,
@OnError, Session, Remote
 Pluggable and extensible
– Encoders, decoders, sub-protocols

WebSocket Example
@ServerEndpoint("/chat")
public class ChatBean {
Set<Session> peers = Collections.synchronizedSet(…);
@OnOpen
public void onOpen(Session peer) {
peers.add(peer);
}
@OnClose
public void onClose(Session peer) {
peers.remove(peer);
}
...

JavaScript Movers and Shakers

Demo: Backbone.js, Java EE, and Maven

Demo: Angular.js

Useful New Tools and Technologies

Useful New Tools and Technologies
 Post Processors
– Emmet
– SASS/LESS
– CoffeeScript
 Cordova/PhoneGap
 HTML5 Ecosystem
– Grunt
– Karma
– Bower
– Yeoman

Demo: SASS, LESS, Karma, Cordova

But Browser/Phone Is Not For Everyone…

Summary
 JavaScript/HTML5 clients gaining traction as opposed to server-side
web frameworks
 Communication between the client and server happens via JSON
over REST or WebSocket
 Java EE well positioned as a JavaScript rich client backend,
especially with JAX-RS, the Java API for WebSocket and JSON-P
 Combining the two worlds is possible and positions applications for
deployment to mobile devices
 More options… more decisions… more technologies to evaluate

JavaCro'14 - Consuming Java EE Backends in Desktop, Web, and Mobile Frontends – Geertjan Wielenga

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JavaCro'14 - Consuming Java EE Backends in Desktop, Web, and Mobile Frontends – Geertjan Wielenga