Mum, I want to be a Groovy full-stack developer

Iván López - @ilopmar
Mum, I want to be a Groovy
full-stack developer

Hello!
I am Iván López
@ilopmar
http://greachconf.com@madridgug

What's a full-stack developer?

Full-stack developer
Backend language
Javascript
HTML
Mobile App

Polaromatic
▷ Spring Boot
▷ Core App
▷ Spring MVC
▷ Spring Integration Flow

<file:inbound-channel-adapter directory="work" channel="incommingFilesChannel"/>
<chain input-channel="incommingFilesChannel">
<service-activator ref="fileService" method="preprocessFile"/>
<service-activator ref="imageConverterService" method="applyEffect"/>
<service-activator ref="browserPushService" method="pushToBrowser"/>
<service-activator ref="metricsService" method="updateMetrics"/>
<service-activator ref="fileService" method="deleteTempFiles"/>
</chain>
Spring Integration Flow

</chain>
Photo preprocessFile(File file) {
def pr = new PolaroidRequest(file)
this.preprocessFile(pr)
}
File service

</chain>
File service
Photo preprocessFile(File file) {
def pr = new PolaroidRequest(file)
this.preprocessFile(pr)
} Photo preprocessFile(PolaroidRequest polaroidRequest) {
String outputFile = File.createTempFile("output", ".png").path
return new Photo(input: polaroidRequest.inputFile.absolutePath,
output: outputFile, text: polaroidRequest.text)
}

class ImageConverterService {
private static final String DEFAULT_CAPTION = "#LearningSpringBoot with Polaromaticn"
Random rnd = new Random()
Photo applyEffect(Photo photo) {
log.debug "Applying effect to file: ${photo.input}..."
def inputFile = photo.input
def outputFile = photo.output
double polaroidRotation = rnd.nextInt(6).toDouble()
String caption = photo.text ?: DEFAULT_CAPTION
def op = new IMOperation()
op.addImage(inputFile)
op.thumbnail(300, 300)
.set("caption", caption)
.gravity("center")
.pointsize(20)
.background("black")
.polaroid(rnd.nextBoolean() ? polaroidRotation : -polaroidRotation)
.addImage(outputFile)
def command = new ConvertCmd()
command.run(op)
photo
}
}
Image converter

FlickrDownloader
▷ Spring Boot CLI
▷ Download Flickr Interesting pictures
▷ Jsoup, GPars
▷ 55 lines of Groovy code
(microservice?)

@Slf4j
@EnableScheduling
@Grab('org.jsoup:jsoup:1.8.1')
@Grab('commons-io:commons-io:2.4')
@Grab('org.codehaus.gpars:gpars:1.2.1')
class FlickrDownloader {
static final String FLICKER_INTERESTING_URL =
"https://www.flickr.com/explore/interesting/7days"
static final String WORK_DIR = "./work"
final File workDir = new File(WORK_DIR)
@Scheduled(fixedRate = 30000L)
void downloadFlickrInteresting() {
def photos = extractPhotosFromFlickr()
withPool {
photos.eachParallel { photoUrl ->
log.info "Downloading photo ${photoUrl}"
def tempFile = download(photoUrl)
FileUtils.moveFileToDirectory(tempFile, workDir, true)
}
}
}
}
FlickrDownloader

FlickrDownloader
@Slf4j
@EnableScheduling
withPool {
}
}
}
}
private List extractPhotosFromFlickr() {
Document doc = Jsoup.connect(FLICKER_INTERESTING_URL).get()
Elements images = doc.select("img.pc_img")
def photos = images
.listIterator()
.collect { it.attr('src').replace('_m.jpg', '_b.jpg') }
photos
}

FlickrDownloader
@Slf4j
@EnableScheduling
withPool {
}
}
}
}
private File download(String url) {
def tempFile = File.createTempFile('flickr_downloader', '')
tempFile << url.toURL().bytes
tempFile
}

FlickrDownloader
@Slf4j
@EnableScheduling
withPool {
}
}
}
}

FlickrDownloader
2016-05-27 21:56:11.139 INFO 16447 --- [111617-worker-1] polaromatic.FlickrDownloader
2016-05-27 22:02:17.019 INFO 9872 --- [pool-1-thread-1] polaromatic.FlickrDownloader

Frontend
▷ MarkupTemplateEngine (HTML)
▷ Websockets
▷ Grooscript

HTML
yieldUnescaped '<!DOCTYPE html>'
html {
head {
title "Polaromatic"
link(rel: 'stylesheet', href: '/css/app.css')
link(rel: 'stylesheet', href: '/css/gh-fork-ribbon.css')
['webjars/sockjs-client/0.3.4-1/sockjs.min.js',
'webjars/stomp-websocket/2.3.1-1/stomp.min.js',
'webjars/jquery/2.1.3/jquery.min.js',
'webjars/handlebars/2.0.0-1/handlebars.min.js',
'js/Connection.js']
.each {
yieldUnescaped "<script src='$it'></script>"
}
}
}

HTML
body {
...
div(id: 'header') {
div(class: 'center') {
a(href: 'https://github.com/ilopmar/contest', target: 'blank') {
img(src: 'images/polaromatic-logo.png')
}
p('Polaromatic')
span('Powered by Spring Boot')
}
}
div(id: 'timeline', class: 'center')
}
script(id: 'photo-template', type: 'text/x-handlebars-template') {
div(class: 'photo-cover') {
div(class: 'photo', style: 'visibility:hidden; height:0') {
img(src: '{{image}}')
}
}
}
yieldUnescaped "<script>Connection().start()</script>"
}

Websockets
@Configuration
@EnableWebSocketMessageBroker
class WebsocketConfig extends AbstractWebSocketMessageBrokerConfigurer {
@Override
void configureMessageBroker(MessageBrokerRegistry config) {
config.enableSimpleBroker '/notifications'
}
@Override
void registerStompEndpoints(StompEndpointRegistry registry) {
registry.addEndpoint('/polaromatic').withSockJS()
}
}

Websockets
class BrowserPushService {
@Autowired
SimpMessagingTemplate template
Photo pushToBrowser(Photo photo) {
log.debug "Pushing file to browser: ${photo.output}"
String imageB64 = new File(photo.output).bytes.encodeBase64().toString()
template.convertAndSend "/notifications/photo", imageB64
return photo
}
}

Websockets
class BrowserPushService {
@Autowired
SimpMessagingTemplate template
Photo pushToBrowser(Photo photo) {
log.debug "Pushing file to browser: ${photo.output}"
String imageB64 = new File(photo.output).bytes.encodeBase64().toString()
template.convertAndSend "/notifications/photo", imageB64
return photo
}
}
</chain>

class Connection {
@GsNative
def initOn(source, path) {/*
var socket = new SockJS(path);
return [Handlebars.compile(source), Stomp.over(socket)];
*/}
def start() {
def source = $("#photo-template").html()
def (template, client) = initOn(source, '/polaromatic')
client.debug = null
client.connect(gs.toJavascript([:])) { ->
client.subscribe('/notifications/photo') { message ->
def context = [image: 'data:image/png;base64,' + message.body]
def html = template(context)
$("#timeline").prepend(html)
$("#timeline .photo:first-child img").on("load") {
$(this).parent().css(gs.toJavascript(display: 'none', visibility: 'visible', height: 'auto'))
$(this).parent().slideDown()
}
}
}
}
}
Grooscript (Javascript)

Android App
▷ Disclaimer: I'm not an Android developer
▷ Lazybones template (@marioggar)
▷ Traits, @CompileStatic
▷ SwissKnife

Android
trait Toastable {
@OnUIThread
void showToastMessage(String message) {
Toast toast = Toast.makeText(applicationContext, message, Toast.LENGTH_SHORT)
toast.show()
}
}

Android
trait Toastable {
@OnUIThread
void showToastMessage(String message) {
Toast toast = Toast.makeText(applicationContext, message, Toast.LENGTH_SHORT)
toast.show()
}
}
@CompileStatic
public class ShareActivity extends Activity implements Toastable {
...
showToastMessage(getString(R.string.share_ok_msg))
...
}

Tests
▷ Spock Framework
▷ Version 1.0 (more than 2 years now)
▷ JUnit compatible (but way better)

Spock
class BrowserPushServiceSpec extends Specification {
void 'should push a converted photo to the browser'() {
given: 'a photo'
def output = File.createTempFile("output", "")
def photo = new Photo(output: output.path)
and: 'a mocked SimpMessagingTemplate'
def mockSimpMessagingTemplate = Mock(SimpMessagingTemplate)
and: 'the push service'
def browserPushService = new BrowserPushService(template: mockSimpMessagingTemplate)
when: 'pushing the photo to the browser'
browserPushService.pushToBrowser(photo)
then: 'the photo is pushed'
1 * mockSimpMessagingTemplate.convertAndSend('/notifications/photo', "")
}
}

Build tool
▷ Gradle
▷ Multiproject to build backend, documentation
and android

Gradle
subprojects {
buildscript {
repositories {
jcenter()
}
}
repositories {
jcenter()
}
}
task wrapper(type: Wrapper) {
gradleVersion = '2.2.1'
}
include 'polaromatic-back'
include 'polaromatic-groid'
include 'polaromatic-docs'
build.gradle settings.gradle

Documentation
▷ Asciidoctor (FTW!)
▷ Gradle plugin
▷ Backends: html, epub, pdf,...

Asciidoctor
buildscript {
dependencies {
classpath 'org.asciidoctor:asciidoctor-gradle-plugin:1.5.2'
}
}
apply plugin: 'org.asciidoctor.convert'
asciidoctor {
sourceDir 'src/docs'
outputDir "${buildDir}/docs"
attributes 'source-highlighter': 'coderay',
toc : 'left',
icons : 'font'
}

Asciidoctor
[source,xml,indent=0]
.src/main/resources/resources.xml
----
include::{polaromaticBackResources}/resources.xml[tags=appFlow]
----
<1> Define the integration with the file system
<2> Preprocess the file received
<3> Apply the Polaroid effect
<4> Send the new photo to the browser using Websockets
<5> Update the metrics
<6> Delete all temporary files

Asciidoctor
[source,xml,indent=0]
.src/main/resources/resources.xml
----
include::{polaromaticBackResources}/resources.xml[tags=appFlow]
----
<1> Define the integration with the file system
<2> Preprocess the file received
<3> Apply the Polaroid effect
<4> Send the new photo to the browser using Websockets
<5> Update the metrics
<6> Delete all temporary files

<file:inbound-channel-adapter directory="work" channel="incommingFilesChannel"/> 
<service-activator ref="fileService" method="preprocessFile"/> 
<service-activator ref="imageConverterService" method="applyEffect"/> 
<service-activator ref="browserPushService" method="pushToBrowser"/> 
<service-activator ref="metricsService" method="updateMetrics"/> 
<service-activator ref="fileService" method="deleteTempFiles"/> 
</chain>

“
Groovy, groovy everywhere...

Thanks!
Any questions?
@ilopmar
lopez.ivan@gmail.com
https://github.com/ilopmar
Iván López
http://bit.ly/fullstack-groovy

Mum, I want to be a Groovy full-stack developer

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