Downloaded 19 times
![API : links on JSON
implicit val AccountWrites = new Writes[Account] {
override def writes(account: Account): JsValue =
Json.obj(
"id" -> account.id,
"email" -> account.email,
"creationDate" -> account.creationDate.toString(),
"links" -> Json.obj(
"self" -> routes.AccountDetailCtrl.get(account.id).url,
"alerts" -> routes.JobAlertDetailCtrl.getAlertsOf(account.id).url,
"cv" -> routes.CvDetailController.getCvOf(account.id).url
)
)
}](https://image.slidesharecdn.com/legacyscala-150629135321-lva1-app6892/85/How-and-why-we-evolved-a-legacy-Java-web-application-to-Scala-and-we-are-still-alive-73-320.jpg)
![Error Handling in Services
sealed trait NewsletterError
case object InvalidNewsletterActivationToken extends NewsletterError
case object NewsletterUpdateError extends NewsletterError
class NewsletterActivator @Inject() (...) {
def activate(code: String): Future[Either[NewsletterError, Boolean]] = ???
}](https://image.slidesharecdn.com/legacyscala-150629135321-lva1-app6892/85/How-and-why-we-evolved-a-legacy-Java-web-application-to-Scala-and-we-are-still-alive-77-320.jpg)
![Error handling in controllers
implicit class ApiErrorRecover(result: Future[Result]) {
def recoverApiError(message: String) =
result recover {
case NonFatal(e) => InternalServerError(
Json.toJson(SimpleError(message))
)
}
}](https://image.slidesharecdn.com/legacyscala-150629135321-lva1-app6892/85/How-and-why-we-evolved-a-legacy-Java-web-application-to-Scala-and-we-are-still-alive-79-320.jpg)
![Loving Case Class And Constructors
case class Account(
id: Option[BSONObjectID] = None,
email: String,
creationDate: DateTime,
optin: Boolean = false,
optoutScenario: Option[DateTime] = None,
source: String = Account.DEFAULT_SOURCE,
deletionDate: Option[DateTime] = None)
Account(“chucknorris@gmail.com”,
creationDate = creationDate,
optin = true)](https://image.slidesharecdn.com/legacyscala-150629135321-lva1-app6892/85/How-and-why-we-evolved-a-legacy-Java-web-application-to-Scala-and-we-are-still-alive-103-320.jpg)
Uploaded byKatia Aresti
How and why we evolved a legacy Java web application to Scala... and we are still alive!
The document discusses the evolution of a legacy Java application to Scala, focusing on the challenges faced due to technical debt and a monolithic architecture. It outlines the migration strategy to a more efficient system using Scala and MongoDB, detailing the implementation of a simplified data model and the use of various testing frameworks. The document also highlights the team dynamics, project management approaches, and the overall transition from a complex legacy system to a modern architecture.
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Similar to How and why we evolved a legacy Java web application to Scala... and we are still alive!
How and why we evolved a legacy Java web application to Scala... and we are still alive!
- 1. How and whywe evolved a legacy java application to scala And we are still alive ! 24/06/2015
- 2.
- 3.
- 4. Software is morelike Madonna
- 5.
- 6. Web applications getold (very) fast
- 7. Continuous small refactoringdoes not avoid long-term technical debt
- 8.
- 9.
- 10. French Job SearchWebsite Launched in 2000
- 11.
- 12.
- 13. High Cost AddingNew Functionalities High Technical Debt
- 14. Coupled Architecture S OA Spaghettis Oriented Architecture
- 15. Lack of realKPI
- 16. In a 100%Linux Environment
- 17.
- 18.
- 19. DAO ServiceBatch MVC RDMS Anonymous User Job Search,Detail, Newsletter
- 20. DAO ServiceBatch MVC RDMS Anonymous User Job Search,Detail, Newsletter Jobs
- 21. DAO ServiceBatch MVC RDMS Anonymous User Job Search,Detail, Newsletter Jobs Jobs External App
- 22. DAO ServiceBatch MVC RDMS Anonymous User Job Search,Detail, Newsletter Jobs Jobs External App Connected User Board CV, Mail Alert, Newsletter
- 23. DAO ServiceBatch MVC RDMS Anonymous User Job Search,Detail, Newsletter Jobs Jobs External App Data Mailing App Connected User Board CV, Mail Alert, Newsletter
- 24. DAO ServiceBatch MVC RDMS Anonymous User Job Search,Detail, Newsletter Jobs Jobs External App Data Mailing App External App Connected User Board CV, Mail Alert, Newsletter
- 25. DAO ServiceBatch MVC RDMS Anonymous User Job Search,Detail, Newsletter Jobs Jobs External App Data Mailing App External App Mobile Version Connected User Board CV, Mail Alert, Newsletter
- 26. DAO ServiceBatch MVC RDMS Anonymous User Job Search,Detail, Newsletter Jobs Jobs External App Data Mailing App External App Mobile Version Connected User Board CV, Mail Alert, Newsletter
- 27. DAO ServiceBatch MVC RDMS External App Connected User Board CV,Mail Alert, Newsletter Anonymous User Job Search, Detail, Newsletter Non connected Alerts, Newsletter Jobs Jobs External App Data Mailing App Mobile Version Partners
- 28. How do wefix this
- 29.
- 31. Where do westart
- 32. DAO ServiceBatch MVC RDMS External App Jobs Jobs External App Data Mailing App Mobile Version Partners Connected User Board CV,Mail Alert, Newsletter Anonymous User Job Search, Detail, Newsletter Non connected Alerts, Newsletter
- 33. Mars – September2014 User Board
- 34.
- 35. DAO ServiceBatch MVC RDMS Data Mailing App Where do westart ? User Board Front-End REST API Mongo Partners
- 36. DAO ServiceBatch MVC RDMS Data Mailing App Where do westart ? User Board Front-End REST API Mongo Partners
- 37. DAO ServiceBatch MVC RDMS Data Mailing App Where do westart ? User Board Front-End REST API Mongo Partners
- 38. DAO ServiceBatch MVC RDMS Data Mailing App Where do westart ? User Board Front-End REST API Mongo Partners External App
- 39. DAO ServiceBatch MVC RDMS Data Mailing App Where do westart ? User Board Front-End REST API Mongo Partners External App
- 40. DAO ServiceBatch MVC RDMS Data Mailing App Where do westart ? User Board Front-End REST API Mongo Partners External App Data Batch
- 41.
- 42.
- 43.
- 44. Focus on technicalchoices
- 45. Main Language • Growingand Solid Community • Powerful Frameworks and Utilities • JVM
- 46. Backend • REST oriented •Template Type Safe • Hot Reloading • “Simplifies” Scala • Reactive programming
- 47. Batch System • Actors •Scale Up – concurrency • Scale Out – remoting • Fault Tolerance
- 48. Front End • Sassbuilt in with play • AngularJS, popular, community, experience • Foundation, solid and easy CSS framework
- 49. Database • Flexible schema •Document oriented makes sense with CVs • Low transactions • Application code rules the database schema – Already the case with SQL Server • No DBA* – We rule the database as dev
- 50.
- 51. Status • +10 yearsof candidate data • Crucial for business • Cannot fail really, C A N O T F A I L !!
- 52. Strategy • Start migrationas soon as possible – Started in April – Mai • Migrate data incrementally • Verify as much as possible • Legacy ID
- 53. Akka Actors • Oneactor per data • Concurrence execution when possible • Handle updates for the crucial moment => between SQL Server Stop and MongoDB Up
- 54. Madrid MUG This sectionis specially dedicated to the Madrid MUG Members
- 55. SQL Model • 8tables for the user profile • Complex joins • SQLServer => Lost in a Linux World • Devs => Backup, dump …
- 56.
- 57. MongoDB Model • 1document / profile • Object <> Document • Simplified model – Option Scala • Using Reactive Mongo Driver • Using Jongo in Java
- 58.
- 59. Model choices • ++reads / -- writes • Stable Reference data * – Sometimes sectors can change… • Low and non risky transactions – Ex : user deletes account
- 60.
- 61. Unit Testing • UsingSpecs framework • Using Mockito – Not as useful as in Java • Some tests are not necessary – Constructors, Builders … Scala Type Safe and Immutability
- 62. Testing the FrontEND • Unit testing JS with Karma • Selenium – Very fragile tests – Proxy Nightmare – Endless navigator problems – Just vital tests after production
- 63. API Tests areCRUCIAL
- 64. Testing the RESTAPI • No Mocking MongoDB • Using Embedded Mongo • Start and Stop Mongo once for every test – DRY data is a hard part https://github.com/flapdoodle-oss/de.flapdoodle.embed.mongo
- 65.
- 66.
- 67. SCALA USER GROUP Thissection is specially dedicated to the Madrid Scala User Group. Thank you to Nouhoum Traoré who spoke about it at scala.io in Paris
- 68. Front-end ● Client API ●No DB Access ● Mostly Javascript Code
- 69. Front-end ● 9 %Scala ● 26.2 % CSS ● 64.8 % JS
- 70. Le frontend :asset pipeline pipelineStages := Seq(rjs, digest, gzip)
- 71. Le frontend :asset pipeline curl http://keljob.com/assets/js/e454f1013e30b783818c8efaf3a8e3a5-startup.js HTTP/1.1 200 OK Cache-Control: public, max-age=31536000 Content-Length: 171997 Content-Type: application/javascript; charset=utf-8 Date: Tue, 14 Oct 2014 22:39:23 GMT ETag: e454f1013e30b783818c8efaf3a8e3a5 Last-Modified: Wed, 08 Oct 2014 12:35:10 GMT
- 72. Compressing content import play.api.mvc._ importplay.filters.gzip.GzipFilter object Global extends WithFilters(new GzipFilter()) { ... }
- 73. API : linkson JSON implicit val AccountWrites = new Writes[Account] { override def writes(account: Account): JsValue = Json.obj( "id" -> account.id, "email" -> account.email, "creationDate" -> account.creationDate.toString(), "links" -> Json.obj( "self" -> routes.AccountDetailCtrl.get(account.id).url, "alerts" -> routes.JobAlertDetailCtrl.getAlertsOf(account.id).url, "cv" -> routes.CvDetailController.getCvOf(account.id).url ) ) }
- 74. Single responsibility Object: Controllers @Singleton class AccountValidationController @Inject() ( accountValidator: AccountValidator) extends Controller { def validateAccount(token: String) = Action.async { request => accountValidator.validate(token).map { case Some(account) => Ok(Json.toJson(account)) case _ => UnprocessableEntity(Json.toJson(InvalidToken)) } }
- 75. Single responsibility Object: Services class AccountAuthenticator @Inject() (...) class AccountValidator @Inject() (...) class AccountCreator @Inject() (...) class AccountSettingsUpdater @Inject() (...)
- 76. Single Responsibility Object: Actors import akka.actor._ ... class CvExporter(...) extends Actor { def commonBehavior(): Receive = ??? def deleteBehavior(): Receive = ??? def updateBehavior(): Receive = ??? def receive = commonBehavior orElse updateBehavior orElse deleteBehavior }
- 77. Error Handling inServices sealed trait NewsletterError case object InvalidNewsletterActivationToken extends NewsletterError case object NewsletterUpdateError extends NewsletterError class NewsletterActivator @Inject() (...) { def activate(code: String): Future[Either[NewsletterError, Boolean]] = ??? }
- 78. Error handling incontrollers class NewsletterActivationController ( newsletterActivor: NewsletterActivator) extends Controller { def activate(token: String) = Action.async { request => newsletterActivor.activate(token).map { … case InvalidNewsletterActivationToken => ??? case NewsletterUpdateError => ??? … }.recoverApiError("Oops !!!") } }
- 79. Error handling incontrollers implicit class ApiErrorRecover(result: Future[Result]) { def recoverApiError(message: String) = result recover { case NonFatal(e) => InternalServerError( Json.toJson(SimpleError(message)) ) } }
- 80.
- 81. The (original) Team •3 Developers and a Product Owner – Legacy + Backend + Scala – Full-Stack – Java + Backend + MongoDB • From 5-10 years of experience • People who are able to leave their confortable coding zone • Want to communicate
- 82.
- 83.
- 84.
- 85.
- 86.
- 87.
- 88.
- 89.
- 90.
- 91.
- 93.
- 94. We have asituation …
- 95.
- 96. SCALA Warning ! Thissection might contain some trolls
- 97. Personal journey toScala
- 98. SIMPLE ??? BuildTool "de.flapdoodle.embed" % "de.flapdoodle.embed.mongo" % "1.46.0” "org.mongodb" %% "casbah" % "2.5.0"
- 99.
- 100.
- 101.
- 102. DI Framework vsCake Pattern @Singleton class LoginController @Inject() (accountAuthenticator: AccountAuthenticator) extends Controller trait LoginController { this: Controller with UserServiceComponent => object LoginController extends LoginController with Controller with MongoDbUserServiceComponent
- 103. Loving Case ClassAnd Constructors case class Account( id: Option[BSONObjectID] = None, email: String, creationDate: DateTime, optin: Boolean = false, optoutScenario: Option[DateTime] = None, source: String = Account.DEFAULT_SOURCE, deletionDate: Option[DateTime] = None) Account(“chucknorris@gmail.com”, creationDate = creationDate, optin = true)
- 104. After 2-3 monthsas happy as being at Machu Picchu
- 105.
- 106.
- 107. Once in production –Creating accounts more easily – Parsing CV on upload – Can apply with the CV – Follow applications • And other awesome stuff built fast and furiously !
- 108. January – March2015 Search and Relooking
- 109.
- 110. BatchData Mailing App 2015 Web Front- End User REST API Mongo Partners inWIP External App Data Search REST API Elastic Search Batch
- 111.
- 112. Challenge 2 :Performance • Gatling – Play! • Comparing performance
Editor's Notes
- #12 Already rebuilt in 2008
- #15 Every developer I’ve spoken about it has already passed by it
- #30 Modulable Scalable REST oriented API First KPI
- #53 Stratégie de migration des données. Comment minimiser le delta ! Offline ! Beaucoup tester car les erreurs sont difficiles à corriger des semaines après. Commencer le plus tôt possible. Minimiser l’adhérence à la base quand on communique avec des systèmes externes !
- #69 Zéro accès à la DB : Flexibilité => séparation du contrat (JSON) et de l’implémentation + non duplication de la logique.
- #70 Stats Github. Plus dynamique, feedback utilisateur….
- #71 Easy
- #72 Easy
- #73 Trop facile !
- #74 JSON généré, play reverse routing et hypermedia. Souligné que c’est une version simplifiée du JSON réel !
- #75 Un mot sur la gestion des erreurs plus tard.
- #76 Un mot sur la gestion des erreurs plus tard.
- #77 Un mot sur la gestion des erreurs plus tard.
- #78 Gérer les erreurs
- #80 URI simple : pas grand chose à dire sur les routes. Facile de se conformer aux URI style REST. Pas mis les noms de package pour avoir de la place.
- #85 We started using Kanban and Agile Zen as a Board
- #86 Lack of testing, running to fast
- #94 Every week demo ; after 3 weeks