Dynamic and rich web application using the good ol\' JVM - Java One Brazil
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December 9th 2010JavaOne 2010
Daniel López JanárizWeb developer
Universitat de les Illes Balears (UIB)JavaTools Community @ java.net
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
Dynamic and rich web application using the
good ol' JVM
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
Introduction
Web applications turned the development world upside down.
Ever changing requirementsHeterogeneous equipment (client OS, browsers,
application servers, server OS)Heterogeneous teams (programming, designing,
SEO, accesibility, usability...)Development in “web time”“Peter Pan” technology
And then we have to choose...
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
Introduction II
What technology?How to choose?Which ones to try? What is important?
Adoption?Compatibility?Background?
Is there any “magic bullet”?That makes our team look like this...
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
Introduction III
How can we improve the situation:Learn the various choices you can make so you can
decide between themAdapt your architecture to the web development
world.So, we are here to:
Showcase some technologies that can be used in the Java plattform.
Demonstrate that an architecture can be adaptable.The end goal is that the choice looks like...
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
Learning: why the JVM?
Java is/was popular for a reason. Among other thingsVery good virtual machineTons of libraries, utilities, frameworks, API...
So, should we start from scratch?Sometimes not possible (100% one-step migration)Small steps help you move from a safe location to a
closer safe location.
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
Learning: how?
The JVM is a bytecode interpreter/dynamic compiler so...
Generate compatible bytecode from the new language. (ex. Scala)
Implement in bytecode an interpreter for the new language. (ex. BeanShell)
Combine both solutions. (ex. Groovy)The “interpreted” languages can be accessed
Through a custom APIThrough the Java Scripting API (JSR-232, Java >=6)
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
Learning: Java Scripting API
ScriptEngineManager theScriptEngineManager = new ScriptEngineManager();ScriptEngine theSE = theScriptEngineManager.getEngineByExtension(extension);Reader reader = ...;...// To interpret the script directlytheAnswer = theSE.eval(reader);
// If you call a function inside the scripttheSE.eval(reader);Invocable inv = (Invocable) theSE;theAnswer = inv.invokeFunction(functionName);
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
Architecture: How to be prepared?
In order to be able to adapt to different requierements, we will use an architecture built around the Separation of Concerns (SoC) pattern.The overall goal is to have an architecture where the different parts communicate through clearly defined interfaces, so the don't step into each other toes.Using an “opinionated” artechitecture with tight integration brings other advantages and drawbacks.
But don't go overboard with it or...
… it will look like this:
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
Architecture: Tiers
This is the web development SoC architecture we have usedWhere we have separated these main Concerns:
User interfacePresentation logicControllerApplication/business logicPersistence
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
Architecture: Showcase application
A simple CRUD application on one table(Items).Every “concern” is implemented with different technologies:
To test if they really can be used independently.To find out some of the benefits and drawbacks of each
alternative.To do some mythbusting!
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
Showcase: Implementations
PersistenceOracle, HSQLDB
Business logic JDBC, Hibernate, JPA, Ibatis, Groovy(x2), JRuby, JavaScript(x2),
Jython, Scala, Pnuts, PHP, PL/SQLController
WebLEAFPresentation logic
JSP, FreeMarker, XSLT, GroovletsUser interface
HTML, RIA: JavaScript (ExtJS, GWT), Flex, Java (Applet, JWS)Comunications
JSON, XML/HTTP, Web Services
951
Possibilities!!(495 if we exclude the DB)
Application & businessLogic
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
App. Logic: Java/JDBC
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
App. Logic: Groovy
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
App. Logic: Jython
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
App. Logic: Scala
UserInterface
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
UI: HTML
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
UI: JavaScript RIA
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
UI: Flex RIA
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
UI: Java Applet RIA
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
UI: PDF
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
Etc... (demo)
http://localhost:8080/
http://www.greeneyed.org/test/
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
Conclusions
The JVM is not only Java and you don't have to abandon completely the Java platform.There are many different languages with different styles that are more or less useful depending on your needs.Learning different approaches to face all the different challenges is the way to be prepared.SoC architectures are an option to facilitate having different approaches at hand, even though it's not the only one and it is not necessarily the best.Implementing such an experiment is quite an experience and acts as a vaccine against language bigotry.Next question is... is any of this really useful in real life?
We have alredy used it to migrate the business logic from one option to another and reduce memory consumption and CPU load on the DB to move it to the application server so clustering of those elements is more effective.
We have also used it to modify and “spice up” some UIs with some AJAX/JavaScript widgets.
JavaOneSM Brazil 2010 | Dec. 9th | Sala 3 | 2:00 PM | http://www.oracle.com/br/javaonedevelop/en/
Thank you for your attention
Questions?