Simple Pure Java

Simple
Pure
Java

Anton Keks
anton@codeborne.com

Enterprise Architecture
20 years ago a new field was born, addressing

System complexity = more and more
money for building IT systems

Poor business alignment = more difficult
to keep those increasingly expensive
systems aligned with business need

A problem of more cost, less value
Today: even more cost, even less value

Your average Java (web) app
● Framework (JSF?)
● Model
● Portal?
● Services!
● Remote services, SOA, EJB
● JNDI
● Stubs, generated code
● How many layers?

...
● Patterns!
● Factory, Singleton, Facade
● Enterprise patterns!
● DTO, DAO, etc
● Getters/setters
(what's the deal - generate 'em)
● JPA, JAXB
● JMS!

Bad words

Layer Tier Bus
Context Manager
Locator Assembler Bean
Broker Facade
Transfer Object DAO
…
It's always nice to see guys like
SessionServiceContextManager
or AbstractStrategyFactoryProxyFacadeBuilder

EAR, WAR, WAR, WAR
Configuration, descriptors!
JNDI!
ESB? ;-)

Must be a wizard to make it all run!
Improves job security index :-)

For a small thing we create
● ManagedBean
● MegaServiceWrapper
● CoreServiceLocal, Stub (JNDI lookup?)
● CoreService (&& CoreServiceImpl)
● AggregatedService
● ConcreteService
● ConcreteDAO
● JPAAdapter

● ...

The result? ☠
● It kills productivity
● Thousands lines of code, very few
functionality
● Well hidden ”business logic”
● N minute deploy time (+ N minutes app
server startup)
● Oops, sometimes redeploy doesn't work,
need to restart
● Slow UI responsivness

What to do?
● Concentrate on domain terminology
● This was the intention of OOP

● Avoid overly defensive code
● You are not writing a framework!
● Fellow developers are friends

● Follow Clean Code by Robert C. Martin

Java platform and language
● Java (EE) is a victim of JCP
● Many unreal/unusable JSRs
● Stick to proven open-source stuff
● Less standards – the better
● Java language is ok
● The biggest miss are closures
● DSLs are possible: Mockito, LambdaJ
● Don't bloat (generate) your code

Code style
● Is your code style limiting readability?
● Avoid too many line breaks and braces
● Emphasize what is important

public int size() { public int size() {
if (root == null) { if (root == null) return 0;
return 0; return root.numSiblings();
} }
else {
return root.numSiblings();
}
public int size() {
}
return root != null ?
root.numSiblings() : 0;
}

Code style
● Avoid over-indenation (or code ladder)
public void startCharging() {
if (customer.hasFunds()) {
if (!station.isCharging()) {
if (!station.currentlyBooked()) {
reallyStartCharging();
return;
}
}
}
throw new UnableToStartException();
}
public void startCharging() {
if (!customer.hasFunds()) throw new UnableToSta
if (station.isCharging()) throw new UnableToSta
if (station.currentlyBooked()) throw new Unable

reallyStartCharging();
}

Code style
● Prefer shorter code (use static imports)
List<Integer> list = Arrays.asList(1, 2, 3));
list = Collections.unmodifieableList(list);
return list;

import static java.util.Arrays.*;
import static java.util.Collections.*;
...

return unmodifiableList(asList(1, 2, 3))

Looks a bit like functional programming, isn't it?

Code style
● Prefer good naming to comments
● Avoid getters/setters, equals, hashCode,
toString unless necessary
● Break free from 'conventions'
● Work towards a DSL

when(session.currentUser()).thenReturn(fakeUser);

assertThat(person.age, is(25));

sort(people, on(Person.class).getAge());

Proper Java app
● Jetty Launcher (esp in development)
● Know the APIs well: servlets, filters, etc
● Avoid vendor-specific stuff
● Keep environment-specific configuration
in version control
● Dependency Injection
● Avoid scattering cross-cutting concerns
● DB migrations (w/ liquibase/dbdeploy)

● Start thin and simple, prefer higher SNR

Web UI
● Your framework tells you don't need to
know JavaScript? (GWT, JSF, etc)
● B.S.!
● Keep it under control: learn basics of
JQuery instead
● Knockout.js, Backbone.js can help
● You are not limited with Java syntax on
the client side :-)

Worth reminding...

● Don't Repeat Yourself
● Keep It Simple Stupid

● You Ain't Gonna Need It

● Test Driven Development

Let's continue on
github:
github.com/angryziber/simple-java

job@codeborne.com

Simple Pure Java

Related slideshows

More Related Content

Simple Pure Java