Download pdf - Developing applications with Cloud Services #javaone 2012

DEVELOPING WITH CLOUD SERVICESChris Richardson

Author of POJOs in ActionFounder of the original CloudFoundry.com

@[email protected]://plainoldobjects.com/

Presentation goal

How to build robust, scalable applications with

Cloud Services

About Chris

(About Chris)

About Chris()

About Chris

About Chris

http://www.theregister.co.uk/2009/08/19/springsource_cloud_foundry/

vmc push About-Chris

Developer Advocate for CloudFoundry.com

Signup at http://cloudfoundry.compromo code: cfjavaone

Agenda

• Why use cloud services?

• Developing location-based applications

• Building SMS and telephony enabled applications

• Developing robust, fault tolerant applications

Three phases of every galactic civilization

Survival

Inquiry

Sophistication

Three phases of every galactic civilization

How

Why

Where

can we eat?

do we eat?

Where shall we have lunch?

Where shall we have lunch?

Solved by VoteMeetEat.com

VoteMeetEat.com

•What restaurants are nearby?•Which friends are close by? •Where do your friends prefer to eat?

To sign up text "register" to 510-555-????

VoteMeetEat.com

Restaurant database +

SMS +

Voice callsTo sign up text

"register" to 510-555-????

Key story: registration

5551212

Key story: registration

+5105551212

Key story: voting

555 1212

Key story: announce location

VOTEMEETEAT.COM

To sign up text "register" to 510-555-????

High-level architecture

VoteMeetEat

TelephonyIntegration

Friend GeoDatabase

Restaurant Database

MobilePhone

Do we really want to build all this?

DIY = DIFFICULT

Use cloud-based services

• Highly scalable services

• Someone else’s headache to develop and maintain

• Provided by IaaS/PaaS

• Provided by 3rd party

Cloud Foundry services

Thousands of 3rd party services

http://www.programmableweb.com/apis/directory

http://www.slideshare.net/jmusser/j-musser-apishotnotgluecon2012

• Predominantly REST

• Predominantly JSON

• > billion API calls/day: Twitter, Google, Facebook, Netflix, Accuweather, ...

• Increasing number of API-only companies

http://www.slideshare.net/jmusser/j-musser-apishotnotgluecon2012

Cloud service trends

Diverse

Benefits of cloud services

• Someone else’s headache to develop and operate

• Focus on your core business problem

• Get up and running quickly

• Elasticity

• Capex ⇒ Opex

Drawbacks of cloud services

• Complexity and drawbacks of a distributed system

• You are dependent on service provider

Risks of cloud services

Urban Airship’s Strategic Partnership With SimpleGeo Turns Into An Acquisition

Cloud Services-based architecture

VoteMeetEat

TwilioMongoDB

Factual.Com

MobilePhone

DEMO

Agenda





Location-based services are hot!

Client-side APIs for finding location

W3C Geolocation API

BUT what about the server-side?

Lots of really difficult problems

•Scalable, spatial database – CRUD records, find nearby•Data management – database of places, street information•Forward geo-coding: address ⇒ lat/lon

•Reverse geo-coding: lat/lon ⇒ address

•Maps•Directions

Easier to use Geo-aaS

Examples of Geo-aaS

Beware the terms of service

• Maps• Forward and reverse geocoding• Directions• Elevation• Places

• Freely available geographic database

• Various APIs including reverse geocoding

• Business+review database• Neighborhood database

• Places database• Reverse geocoding

VOTEMEETEAT & Geo

trait FriendService { def addOrUpdate(request : AddOrUpdateUserRequest) def findNearbyFriends(request : NearbyFriendsRequest) :

FindNearbyFriendsResponse}

trait RestaurantService { def findNearbyRestaurants(location: Location) :

FindNearbyRestaurantResponse}

Implementing the friends database

MongoDB

• Document-oriented database

• Very fast, highly scalable and available

• Rich query language that supports location-based queries

• Provided by CloudFoundry.com

MongoDB server

Database: VoteMeetEatCollection: friendRecord

Storing friends in MongoDB

{ "_id": "+15105551212", "name": "Chris R.", "location": { "x": -122.25206103187264, "y": 37.847427441773796 }}

Spring Data for MongoDB

• Provides MongoTemplate

• Analogous to JdbcTemplate

• Hides boilerplate code

• Domain object ↔ Document mapping

Using Spring data: creating an index on location attribute

@Componentclass MongoFriendService extends FriendService {

@Autowired var mongoTemplate: MongoTemplate = _

@PostConstruct def createGeoIndex { val dbo = new BasicDBObject dbo.put("location", "2d") mongoTemplate.getCollection("friendRecord").ensureIndex(dbo) }

Create geospatial 2d index

Collection name

Using Spring Data: adding record@Componentclass MongoFriendService extends FriendService {

override def addOrUpdate(request: AddOrUpdateUserRequest) = { val name = request.name val phoneNumber = request.phoneNumber val fr = new FriendRecord(phoneNumber, name, new Point(request.longitude, request.latitude)) mongoTemplate.save(fr) }

case class FriendRecord(id : String, name : String, location : Point)

Using Spring Data: finding nearby friends

@Componentclass MongoFriendService extends FriendService {

override def findNearbyFriends(request: NearbyFriendsRequest) = { val location = new Point(request.longitude, request.latitude) val distance = new Distance(3, Metrics.MILES) val query = NearQuery.near(location).maxDistance(distance) val result = mongoTemplate.geoNear(query, classOf[FriendRecord])

val nearby = result.getContent.map(_.getContent) FindNearbyFriendsResponse(nearby.map(f => FriendInfo(f.name, f.id))) }

MongoDB and Cloud Foundry

$ vmc create-service mongodb vme-mongo

$ vmc push vme-user --path web/target/Application Deployed URL [cer-spring.cloudfoundry.com]: Detected a Java SpringSource Spring Application, is this correct? [Yn]: Memory Reservation (64M, 128M, 256M, 512M, 1G) [512M]:

Creating Application: OKWould you like to bind any services to 'vme-user'? [yN]: y

Would you like to use an existing provisioned service? [yN]: yThe following provisioned services are available

1: vme-mongo2: mysql-135e0Please select one you wish to use: 1

Binding Service [vme-mongo]: OKUploading Application:

Checking for available resources: OK Processing resources: OK

Packing application: OK Uploading (12K): OK

Push Status: OK

Binding a service to an application

Would you like to bind any services to 'vme-user'? [yN]: yWould you like to use an existing provisioned service? [yN]: yThe following provisioned services are available1: vme-mongo2: mysql-135e0Please select one you wish to use: 1Binding Service [vme-mongo]: OK

Connecting to MongoDB <bean id="mongoTemplate"

class="org.springframework.data.mongodb.core.MongoTemplate"> <constructor-arg ref="mongoFactory" /> </bean>

<beans profile="default"> <mongo:db-factory id="mongoFactory" dbname="surveygeo" /> </beans>

<beans profile="cloud"> <cloud:mongo-db-factory id="mongoFactory" /> </beans>

Outside of Cloud Foundry

Inside Cloud Foundry

Implementing the restaurant database

Using Factual

• Geographic database as a Service

• Including 800,000 restaurants in the US

• Pricing: 10K calls day free, pay per use

Factual API

• RESTful/JSON interface

• Uses 2-legged OAuth 1.0.

• Geo and text filters

• Pagination

• Libraries for various languages

Restaurant Service@Serviceclass FactualRestaurantService extends RestaurantService {

@Value("${factual_consumer_key}") var consumerKey: String = _ @Value("${factual_consumer_secret}") var consumerSecret: String = _

var factual: ThreadLocal[Factual] = _

@PostConstruct def initialize { factual = new ThreadLocal[Factual] { override def initialValue() = new Factual(consumerKey, consumerSecret, true) } }

override def findNearbyRestaurants(location: Location) = { val restaurants = factual.get.fetch("restaurants-us", new Query().within(new Circle(location.lat, location.lon, 1000)).limit(5))

val rs = for (map <- restaurants.getData) yield { RestaurantInfo(map.get("name").asInstanceOf[String]) }

FindNearbyRestaurantResponse(rs.toList)

}...

Not thread-safe

5 restaurants within 1km

Agenda





The telephony and SMS are important

http://blog.nielsen.com/nielsenwire/online_mobile/new-mobile-obsession-u-s-teens-triple-data-usage/

7/ waking hr !

Nielsen

Reporting traffic light problems in London

Google 2-Factor authentication

VoteMeetEat.com & Telephony

• Handling registration SMS

• Sending SMS notifying users to vote

• Handling incoming voice call from voters:

• Text-to-speech of restaurants options

• Collecting digits entered via keypad

• Sending SMS notification of voting results

DIY telephony = Difficult

• Difficult to setup and operate

• Expensive

• Complex SMS protocols

• …Bette

r to use S

MS/Telepho

ny-aaS:

Telephony/SMS - aaS

• SMS• Inbound and outgoing calls• Recording and transcription

• SMS• Inbound and outgoing calls• Recording and transcription• Twitter• IM

Twilio - Telephony and SMS as a service

• REST API• Allocate phone numbers• Make and receive phone calls• Send and receive SMS messages

• Pay per use:• Phone calls - per-minute • SMS – per SMS sent or received• Phone number – per month

• Examples• OpenVBX is a web-based, open source phone system• StubHub – notifies sellers of a pending sale via phone• SurveyMonkey – interactive polling• Salesforce – SMS-based voting for 19,000 conference attendees

Using Twilio

Twilio Your Application

TwiML doc

HTTP GET/POST

REST API

Manage resourcesSend SMS

Initiate voice calls

Handle incoming SMS and voice callsRespond to user input

VoiceSMS

Phone number ⇒

SMS URL + VOICE URL

Handling SMS registration

5551212


TwilioSMS

REGISTRATION

HTTP POST http://≪smsUrl≫?From=≪PhoneNumber≫

<Response> <Sms>To complete registration please go to http://... </Sms></Response>

SMS


TwiML document describing the

response

Inviting users to vote

5551212

Inviting users to vote

POST /2010-04-01/Accounts/≪AccountSID≫/SMS/Messages From=+15105551212&To=+14155551212&Body=≪MESSAGE≫Authorization: Basic ....

Basic auth using Twilio AccountSid+AuthToken

Sending SMS using the Spring REST Template

@Componentclass TwilioService {

def sendSms(recipient : String, message : String) = { val response = postToTwilio("SMS/Messages", Map("From" -> twilioPhoneNumber, "To" -> recipient, "Body" -> message)) (response \ "SMSMessage" \ "Sid").text }

Sending SMS using the Spring REST Template

TODO

@Componentclass TwilioService {

def postToTwilio(resourcePath : String, requestParams : Map[String, String]) = { val entity = makeEntity(requestParams)

try { val response = restTemplate.postForObject(twilioUrl +

"/Accounts/{accountSid}/{resource}", entity, classOf[String],

accountSid, resourcePath) XML.loadString(response) } catch { case e : HttpClientErrorException if e.getStatusCode == HttpStatus.BAD_REQUEST => val body = e.getResponseBodyAsString() val xmlBody = XML.loadString(body) val code = Integer.parseInt((xmlBody \\ "Code").text) val message = (xmlBody \\ "Message").text throw new TwilioRestException(message, code) }}

Voting

555 1212

Voting

Twilio

Survey Management<Response> <Say> Chris would like to meet and eat. </Say> <Gather action="handleresponse.html"

method="POST" numDigits="1"> <Say>Press 1 for ....</Say> <Say>Press 2 for ....</Say> </Gather></Response>

HTTP POST http://≪voiceUrl≫?From=≪PhoneNumber≫

Call

Voting

Twilio

Survey Management

<Response> <Say>Thank you for choosing. The most popular place so far is ... </Say> <Pause/> <Say>You will hear from us soon. Good bye</Say> <Hangup/></Response>

HTTP POST http://....handleresponse.html?From=≪PhoneNumber≫&Digits=≪...≫

Digits

Voting code 1@Controllerclass TwilioController { @Autowired var surveyManagementService: SurveyManagementService = _

@RequestMapping(value = Array("/begincall.html")) @ResponseBody def beginCall(@RequestParam("From") callerId: String) = { surveyManagementService.findSurveyByCallerId(callerId) match { case None => <Response> <Say>Sorry don't recognize your number</Say> <Hangup/> </Response> case Some(survey) => <Response> <Say>{ survey.prompt }</Say> <Gather action="handleresponse.html" method="POST" numDigits="1"> { for ((choice, index) <- survey.choices zipWithIndex) yield <Say>Press { index } for { choice }</Say> } </Gather> <Say>We are sorry you could not decide</Say> <Hangup/> </Response> } }

Voting code 2class TwilioController { ... @RequestMapping(value = Array("/handleresponse.html")) @ResponseBody def handleUserResponse(@RequestParam("From") callerId: String,

@RequestParam("Digits") digits: Int) = { val survey = surveyManagementService.recordVote(callerId, digits) <Response> <Say>Thank you for choosing. The most popular place so far is

{ survey.map(_.mostPopularChoice) getOrElse "oops" } </Say> <Pause/> <Say>You will hear from us soon. Good bye</Say> <Hangup/> </Response> }}

Agenda





The need for parallelism

Service A

Service B

Service C

Service D

b = serviceB()

c = serviceC()

d = serviceD(b, c)

Call in parallel

Java Futures are a great concurrency abstraction

http://en.wikipedia.org/wiki/Futures_and_promises

Akka’s composable futures are even better

Using Akka futurestrait FriendService { def findNearbyFriends(request : NearbyFriendsRequest) :

Future[FindNearbyFriendsResponse]}

trait RestaurantService { def findNearbyRestaurants(location: Location) :

Future[FindNearbyRestaurantResponse]}

val friendsRequest = NearbyFriendsRequest.fromLocation(vmeRecord.location)for ( (nearbyFriends, nearbyRestaurants) <-

friendsService.findNearbyFriends(friendsRequest) zip restaurantService.findNearbyRestaurants(vmeRecord.location)

) {

.... }} Two calls execute in parallel

Using external web services = Distributed system

VoteMeetEat

TwilioMongoDB

Factual.Com

MobilePhone

Internally = Distributed System

Survey management

VMEmanagement

Registration SMS

Registrationweb app

VME web app

Usermanagement

RabbitMQ

Handling failure

Service A Service B

Errors happen in distributed systems

About Netflix

> 1B API calls/day

1 API call ⇒ average 6 service calls

Fault tolerance is essential

http://techblog.netflix.com/2012/02/fault-tolerance-in-high-volume.html

Use timeouts and retries

Never wait forever

Errors can be transient ⇒ retry


Service A

Service B

Use per-dependency bounded thread pool


Runnable 1

Runnable 2

Runnable ...

bounded queue

Task 1

Task 2

Task ...

bounded thread pool

Limits number of outstanding requests

Fails fast if service is slow or down

Use a circuit breaker

High error rate ⇒ stop calling temporarily

Down ⇒ wait for it to come back up

Slow ⇒ gives it a chance to recover


Closed Open

Half open

errors

successtimeout

fail

On failure


AvoidFailing

Return cached data

Return default data

Fail fast

WorkerActor

Aspects + Actors

CallerDependency

InvokerAspect

DependencyStub

CircuitBreakerActor

WorkerActor

Implements circuit

breaker state machine

Equivalent of thread pool

@DependencyProxy annotation

@Service@DependencyProxy(circuitBreaker = "factualCircuitBreaker", timeoutInMilliseconds=750)class FactualRestaurantService extends RestaurantService { ...}

trait RestaurantService { def findNearbyRestaurants(location: Location) : Future[FindNearbyRestaurantResponse]}

Aspect-based Async Execution

@Aspectclass DependencyInvokingAspect {

@Pointcut("execution(* (@DependencyProxy *).*(..))") def dependencyProxyMethods {}

@Around("dependencyProxyMethods()") def invoke(jp: ProceedingJoinPoint) = { val a = AnnotationUtils.findAnnotation(jp.getTarget.getClass, classOf[DependencyProxy]) val actor = findActor(a) val timeout = Timeout(a.timeoutInMilliseconds milliseconds) actor.ask(InvokeDependency( () => jp.proceed())) (timeout) }

}

Ask actor to invoke jp.proceed() and return Future

See

https://github.com/cer/votemeeteat

for the Actor code

Summary

Cloud services are highly scalable services developed and operated by a 3rd party

Let’s you focus on your core business problem

Risk: provider is acquired and stops offering service

Developing an application that reliably consumes cloud services requires careful design

Questions?

@crichardson [email protected]://slideshare.net/chris.e.richardson/

Sign up for CloudFoundry.com using promo code cfjavaone