play framework on google app engine - productivity stack

smart.biz.plsmart.biz.pl

Play with GAE

1

Productivity stack: Play Framework on Google App EnginePolish Java User GroupKraków 2016-04-05

@marcinstepienwww.smart.biz.pl

http://www.smart.biz.pl




https://twitter.com/marcinstepien






Marcin Stępień

Developer, [email protected]@marcinstepienlinkedin.com/in/marcinstepien

www.smart.biz.pl

2005

www.whenvi.com

2014

2








https://linkedin.com/in/marcinstepien

https://linkedin.com/in/marcinstepien



http://www.whenvi.com

http://www.whenvi.com


❖ App Engine intro, scaling & limitations

❖ Play Framework stuff

❖ GAE abstraction

❖ How do this two things work together

❖ Play 2 on GAE?

❖ Trade-offs

3

Play Framework + GAE





smart.biz.pl

PlayFramework

Google AppEngine

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PlayFramework

Google AppEngine

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Productivity



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Google Cloud

Compute EngineApp Engine

PaaS IaaS

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Building blocks

App Engine PaaS

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Build toolsScalable

Infrastructure



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Scaling is simplified

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One tier of servers

Instances: - capacity- max / min #- manual / autoscale- warm up /

decommission- traffic splitting

Internet



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Just a drawing

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Internet

load balancer frontend servers backed servers data store

You will not deal with that



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GAE Limitations

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Security sandbox

● Java class whitelist

● Java 7

● Servlet API 2.5

○ no real async WS calls

● No raw socket connections

○ no SMTP etc.

○ Url Fetch service instead

Scalability

● Frontend calls are limited to

30s

● Scheduled Jobs limited to

10min

● Url Fetch limited to max 60s

● Do not share object in session

● NoSQL datastore *

● 200 indexes




https://cloud.google.com/appengine/docs/the-appengine-environments

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GAE Environments







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Play 1, Play 2, Ninja, Spark … Spring Boot, JHipster

Java micro frameworks

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Play 1 Play 2

2008 released 2013

Java first service Scala first, Java

Groovy templates Scala

1 GAE module -

by communitymaintenance mode*

developedby authors and community

by 3rd part. commerce supportby authorsand 3rd part.

Play Framework versions

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There is no HttpServletRequest, HttpSession etc.

Not a JEE Framework

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GAE module wraps Play app into .war file



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There is no server side session

Share Nothing

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#pass value to next request in flash scopeflash.put(“key”, object);

#store in encrypted user cookie, Strings only, 4kbsession.put(“key”, “value”);

#store object in cacheCache.store(“key”, object, “1h”);

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Share Nothing





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hot swapping on dev, just hit F5+

auto scaling on prod

Share Nothing

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GAE gives 2 types. Transparent use for Play developer.

Distributed Cache

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But not on GAE with Servlet 2.5 spec

Play is asynchronous

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#com.ning.http.client.AsyncHttpClient

#not on GAE servlet API 2.5Promise<HttpResponse> res1, res2; res1 = WS.url("http://example1").getAsync();res2 = WS.url("http://example2").getAsync();...

#synchronous call works fineWS.url("http://example").get();

#Json parserWS.url("http://example").getJson();

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WS calls are wrapped in URL fetch





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Siena module instead of GAE JPA

Data store: Active Record pattern

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public class Employee extends Model {

@Id public Long id;public String fullName;public Department dep;

}

public class Department extends Model {

@Id public Long id;@Url public String website;public Date launched;

}

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Data store abstraction






Employee adam = new Employee(“Adam”);Adam.dep = department;adam.save();

welcome(adam);

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Active Record






public class Employee extends Model {

@Id public Long id;public String fullName;#no Joins, dep stores only id fieldpublic Department dep;

#retrieves and maps into objectpublic String getDepWebsite() {

#dep.website is null until you call .get()return dep.get().website;

}}

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Fetching data, no joins






public class Employee extends Model {...

public static List<Employee> getAll(Long depId) {return all().filter(“dep”, new Department(depId)).fetch();

}

public static Query<Employee> all() {return all(Employee.class);

}

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Querying





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Controller is tied to HTTP protocol

RESTful

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#http method, app url (regex), controller method

GET /employee/{id} Employees.userPOST /employee/ Employees.createPUT /employee/{id} Employees.updateDELETE /employee/{id} Employees.delete

GET /employee/show-{id} Employees.showGET /employee/list Employees.list

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Routing






#controller methods are static for Play v. < 1.4public class Employees extends App {

public static void create(Employee em) {em.save();show(em.id); #HTTP 302 redirect

}#template is chosen by conventionpublic static void show(Long id) {

#object passed into Employees/show.htmlrender(Employee.get(id));

}

public static void list() {renderJSON(Employee.all());

}}

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Controller





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Data store, Logging, Cache, Gmail, WS calls etc.

GAE Abstraction

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Is implemented in Play. GAE SDK is hidden.



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GAE tooling

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BigQuery, Security scans, Performance scans, alerts

.



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2. Environment (Java 8, Servlet 3.0 +)

Play 2 on GAE ?

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1. Deployable .war file




https://github.com/play2war/play2-war-plugin

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Play 2 on GAE: war








https://cloud.google.com/appengine/docs/flexible/custom-runtimes/

https://cloud.google.com/appengine/docs/flexible/java/dev-jetty9-and-apis

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Play 2 on GAE: run

Services only via public APIs... Jetty 9 + docker configuration

Flexible runtime Custom runtime









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Trade-offs

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Pros

● Faster deployment

● Scaling

● Google Infrastructure

● maintenance + analytic tools

○ BigQuery etc.

● Abstraction

○ You are not tied with

GAE SDK

Cons

● Sandbox limitations

● Not truly asynchronous on

basic GAE

● Servlet container lowers

application performance

● Watch out for test coverage




[email protected]@marcinstepien

35

Thank you








play framework on google app engine - productivity stack

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