Devoxx 2015 - Web Application Development using Grails and Docker

@tvinke @koenusTweets @First8BV#Devoxx #grails3trek

Web Application Development

using Grails and Docker

`

Workshop by Ted Vinke and Koen Aben

First8


Who are we?

Ted Vinke@tvinke

Koen Aben@koenusTweets

First8@First8BV


Goal

• Get to know Grails 3 – The

Framework

• Acquire hands-on enough

practical knowledge to get

started with a project at

home or work

• Experience the Fun and Joy

of developing with Grails


Contents

• Overview

• Workshop

• Feedback


Updates & Feedback

We’d love to have some feedback afterwards!

www.first8.nl/grails3trek

http://www.first8.nl/grails3trek


Grails?


groovy-lang.org


Much is optional

• Optional braces ( and )

• Optional semi-colons ;

• Less lines

• println instead of

System.out.println

Java

public static void main(String[] args) {System.out.println("Hello world!");

}

Groovy

println "Hello world!"


Less boilerplateParsing XML

def xmlSlurper = new XmlSlurper()

def list = xmlSlurper.parseText'''

<list>

<company>

<name>First8</name>

</company>

</list>

'''

assert

list.company.name == 'First8'

Parsing JSON

def jsonSlurper = new JsonSlurper()

def company =

jsonSlurper.parseText '{"name": "First8"}'

assert company instanceof Map

assert company.name == 'First8'


Duck typing

• Instead of a specific type name you can use def

• Usable instead of void in method definition

• Allows for easy tutorials, but also for "duck typing"

Java

int typed = 2

typed = "Some text"

// compiler error: type mismatch

Groovy

def dynamic = 2

dynamic = "Some text" // ok


More Groovy

•Return keyword is

optional

• Classes, methods and

properties* are public by

default

• Getters and setters are

generated compile-time

Groovy

double calculateTotal(int number) {

number * 0.21

}

Groovy

class Spaceship {String nameboolean warpCapable

}


Groovy Closures

• Block of code; assign with curly braces { and }

Groovy

def clos = { println "Hello Duke!" }

println "Executing the Closure:"

clos() // prints "Hello Duke!"

def adder = { a, b -> print a+b }

adder(1, 2) // prints "3"

adder("m", "e") // prints "me"

with parameters


Lists

• Use [] expression to create a List

Java

List<Person> persons = new ArrayList<>();

persons.add(new Person());

Groovy

def persons = []

persons << new Person()


Maps

• Use [:] expression to create a Map

Java

Map<String, String> map = new HashMap<>();

map.put("name", "Ted");

Groovy

def map = [name:"Ted", id:1234]

assert map.get("name") == "Ted"

assert map["name"] == "Ted"

assert map.name == "Ted"


Groovy as-is

already rocks!


grails.org


“Grails is an Open Source, full stack, web

application framework for the JVM. It

takes advantage of the Groovy

programming language and convention

over configuration to provide a productive

and stream-lined development

experience.”


Distribution

• Latest official

release is 3.0.9

• Latest available

release is 3.1.0.M2

• We’ll be using

3.1.0.M1

For this workshop you don’t

have to download Grails.


Up ‘n running with Grails

1

Install JDK and

Grails

distribution

2

grails create-app MyFirstApp

3

grails run-app


Up ‘n running with Gradle

gradlewbootRun

grails run-app


Workshop Grails Trek


Step 1: grails-trek.zip

Extract zipped Star Trek

workshop application

from the USB stick.

You can keep it! Take your

time during the workshop –

you can always continue at

home.


Material

grails-trek3.zip

Eclipse Mars distributions (Win, Linux and Mac)

Docker Toolbox distributions (Win and Mac)

Documents

A - Getting Started.pdf

B - Eclipse Mars Instructions.pdf

C - Tasks in Eclipse.pdf

D - Docker Instructions.pdf


Step 2: Install IDE

Extract Eclipse Mars from

the USB stick. Install

some plugins and import

the Gradle project.

You can of course use Netbeans or

IntelliJ to import the project and run it with

the Gradle Wrapper, but you won’t be

able to follow the tasks easily…


Step 3: Tasks in Eclipse

Use the Tasks overview

to follow all assignments

in chronological order.

We’ve used the TODOs in such a

way so Eclipse can display them

nicely in chronological order.


Step 4: Docker

Instead of in-memory H2,

run integration test

against Postgres in

Docker container.

Windows and Mac users can install

Docker Toolbox from the USB drive.


Eclipse Mars


Eclipse Mars

Already has:

• Buildship plugin

(Gradle)

Add ourselves:

• Groovy compiler

• GSP editor


Eclipse Mars

• Import grails-

trek/trek as a

Gradle project


Eclipse Mars

• Interact with

Gradle

whenever you

have to -- with

the Gradle

Tasks view


Eclipse Mars

• Follow the

breadcrumbs


What tasks can you encounter? (1)

Showcases of several features - just FYI


What tasks can you encounter? (2)

Coding tasks - which invite you to actually implement

missing logic or fix a bug

• Solutions are present in the enclosed Git repository as tags


Sections

• The 40 tasks are divided in sections

• ENGINEER

• SECURITY

• PARTICLE

• MISSIONS

• AWAYTEAM

• A reference of all tasks and a FAQ can be found in the

Tasks in Eclipse PDF


Install & ENGINEERING

• Get the project up ‘n

running (max 10-20 min)

• Work ENGINEER tasks

• Review in 30 min


Review ENGINEER

1.Starting the app: bootRun

2.UrlMappings:

"/"(controller:"dashboard")

3.Use i18n messages

4.Scaffolding

5.Controller actions/views

6.Controller returning

model

7.GSP using model

8.Auto-reloading

9.404 error page

10.Groovy


SECURITY

• Work SECURITY tasks

• Logging framework

• Testing with Spock

• GSP and TagLibs

• H2 and Hibernate

• Review in 30 min


Review SECURITY

1.Logback logging

framework

2.Testing with Spock

(UserController)

3.Groovy Expressions

4.GSP variables

5.TagLib FYI

6.TagLib impl change

7.TagLib test change

8.TagLib attributes

9.BootStrap

10.dbconsole

11.Dynamic Finders

12.PersonTagLib impl

change


PARTICLE

• Work PARTICLE tasks

• Spring beans, Spring Boot Actuator

• Event processing

• Groovy class annotation

• Grails configuration

• JSON


Review PARTICLE

• Spring beans

instantiation & wiring

• Event processing with

Reactor

• Groovy class annotations

• Grails configuration

• JSON

• Health & metrics


Thank you

• first8.nl

• first8.nl/grails3trek

• twitter.com/First8BV

• linkedin.com/company/first8

Devoxx 2015 - Web Application Development using Grails and Docker

Technology