Rapid Application Development onGoogle App Engine for Java

Kunal Dabir@kdabir

github.com/kdabir

2

Agenda

• Introduction• Rapid Apps – when?• Options• Developing on GAE/J– Pricing – Architecture– What’s wrong– Simpler way

• Demo– Build and deploy a

simple site.• Better Practices• Q & A

3

About the Talk• Level: Basic / Introductory

• Warning: There will be <code>– Some Programming knowledge of Java/Html

• Based on my own experiences:– Working in different web technologies and– Cloud hosting solutions

• Takeaways : – Get your app on cloud in a snap– Learn a thing or two about GAE/J

4

About Me• Programming for more than a decade

• Currently working at ThoughtWorks

• Language Enthusiast: – Java, Groovy, Ruby, JavaScript (Node), CoffeeScript, Scala,…..

• Groovy Evangelist

• Co-Organizer / Speaker: Pune Java User Group

• More at: kunaldabir.appspot.comFacts as on Sept 2013

5

Quick Poll - Who all:• Do Java web apps?

• Have used Google App Engine?

• Have heard of Groovy Language?

• Understand NoSQL data store?

• Deployed an app ?– (cloud/shared hosting /VPS/ anywhere)

• Enjoy programming?

6

Rapid App Development - When ?

• Prototyping

• Personal Pet Project

• Utility Apps

• REST API

7

Rapid App Development - When ?

• Not more than a few pages

• Data Records in thousands

• When time to market is critical

• When resources are limited

8

Options

• Google App Engine – google

• Heroku - salesforce

• CloudFoundry - vmware/spring

• OpenShift - Redhat/jboss

• dotCloud, EngineYard, Joyent, Cloudbees ....

9

Google App Engine - Benefits

• Quick to get development started

• Easy Provisioning

• No Operations

• Horizontal (Auto) Scaling

• Language Support : Python, Java, Go and PHP

10

GAE Has it all• DataStore

• Memcache

• Blobstore

• Users API

• Channel API

• Backends

• Images API

• Logging

• Mail API

• Capabilities API

• Multitenancy

• Task Queue

• Cron Jobs

• URLFetch

• XMPP

• Static File Server

11

At High Level

DataStore HRD• One for app• Multi tennancy• Shared between

version

App Servers• App Code• Auto Scaled• Multi Versioned

Static Web Server• CSS/JS/HTML• Fast Response• Always On

12

Pricing

• Free to start

• Enable Paid app, get resident instance.

• A lot cheaper than competition

• 28 free instance hours $0.08 / hour

• https://cloud.google.com/pricing/

13

The Java Way - What’s Wrong?

As a java web developer:

• Puzzled with OO soup, getters setters, syntactic noises

• Framework hell, Mix and match.

• XML noise or interspersed annotations@@@@

• Deployment ?? where ?? nothing free

14

The Java Way - What’s Wrong?

• Complex Builds– And the Builds files (verbose, xml)

• Nested directory structure of java web apps

• Using the SDK directly– Or the eclipse plugin (can’t build outside IDE)

• Ceremony and Boilerplate

15

The Java Way - What’s Wrong?

import java.io.*;import javax.servlet.*;import javax.servlet.http.*;

public class HelloWorld extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{

response.setContentType("text/html");

PrintWriter out = response.getWriter(); out.println("Hello World"); } }

16

Enter Glide

• Easy Install

• No configuration, well almost

• No complicated directory structure

• Hot reload

• No Lock-in, export to gradle project

17

Built on Awesome technoloG’s

• Google App Engine

• Groovy

• Gaelyk

• Gradle

• Git

• GitHub

18

Gaelyk Recap - Persistence

import com.google.appengine.api.users.Userimport groovyx.gaelyk.datastore.*

@Entityclass Post { String title String content @Indexed Date date = new Date() User user}

19

Gaelyk Recap - Controller

new Post(title: params.title, content: params.content, user: users.currentUser

).save()

log.info "Post Saved"

redirect "/"

20

Gaelyk Recap - Routing

get "/", forward: "/home.gtpl" , cache: 10.minutes

get "/docs/@doc", forward: "/_doc.groovy?docname=@doc"

get "/docs/", redirect: "/docs/intro"

post "/create", forward: "/_create.groovy"

all "/install", forward: "/install.html"

21

Using Glide

You need to know only three commands :

$ glide run

$ glide deploy

$ glide export

22

Configuration Files

• Only three config files, All optional

__glide.groovyDiscussed in next section

__routes.grovyThe gaelyk routes file we just saw

__build.gradleUsed to customize build. Not discussed here.

23

Configure Glide App

• Required to deploy app. • Use the registered app-id

app { name = "app-id" version = "v1"}

24

Layout Template

Sitemesh enabled by default

layout { mappings = [ "/*": "/_layout.html" ]}

25

Security

• Authentication– Use ubiquitous Google id– Or open Id (experimental)– Can Allow only administrator

web { security = [ 'admin': ["/post/*"], '*': ["/view/*"] ]}

26

Demo

27

Getting more mileage• Use CDN

• Hotlink JS Libraries, CSS and Images

• Use static landing page

• Use memcache

• Cache pages

• Enable PageSpeed

• Multiple versions

28

Trade Offs

• Performance

• Slower cold start

• Learning curve

• Difference b/w Local and Live GAE server

29

Question Answers

• Questions are guaranteed in Life, Answers aren’t

30

Resources

• Glide : – http://glide-gae.appspot.com

• Gaelyk : – http://gaelyk.appspot.com

• Group: – http://groups.google.com/forum/#!forum/glide-groovy

• Github: – https://github.com/kdabir/glide