Decathlon’s mission is to make sport accessible to more people. Decathlon SportMeeting, its new social network, was created to take this one step further, allowing everyone to find people who share their sport and their passion. DSM was defined from scratch to support the actual traffic with more than 100k registered users, 1000 active sport proposals for more than 30 sports. This web platform is entirely built with Groovy & Grails but there are also applications in Android and iOS that use its RESTful API. Along the development process several plugins were created and open-sourced to the community. In this talk Kaleidos will explain how the development of this platform was, some of the technical decisions that were made, lessons learned, pitfalls or how the infrastructure has been evolving for almost 3 years, and much more.

1. Decathlon Sport Meeting
Alonso Torres, DEVELOPER
Sports, a new Grails discipline
Antonio de la Torre, DEVELOPER
Kaleidos

2. Introduction

3. What’s Decathlon Sport Meeting?
Intro

4. Intro
Why want Decathlon to develop a Social Network?
● Decathlon’s mission is to make sports widely available
● Sport Meeting was created to take this one step further

5. Intro
Who developed it?
Kaleidos

6. What did it contributed to the community?
● 3 Pull Request to Grails
GRAILS-11647, GRAILS-11323, GRAILS-10763
● 6 open sourced plugins
Intro

7. Intro
How is DSM?
100k registered users
1000 active sport proposals
35 sports

8. Development Decisions
«The risk of a wrong decision is preferable
to the terror of indecision.»
Maimónides (12th c.)

9. Development decisions
Divided in
three applications
● WEB, JOBS, API
and a plugin with business
logic and common code
● CORE
JOBS
WEB API
CORE

10. Development decisions
Command Objects
● Responsibility
● Validate objects
○ accessing model to validate data

11. Development decisions
Command Objects
Check if is a type
and a valid domain object

12. Development decisions
Tests
● Start with Integration tests << due to odd behaviour
● and moving to Unit tests << less dependency

13. Development decisions
Asynchronous processes and background jobs
● Asynchronous processes (platform-core)
○ Immediate email sending
○ Push notifications to mobile devices

14. Development decisions
Asynchronous processes and background jobs
● Background jobs (quartz)
○ Quartz scheduler library
○ Tasks that are processed overnight
■ Proposals clean up
■ Mailing with interesting stuff (users, proposals)

15. API Decisions

16. API decisions
Trait with helpers to create responses: 4XX

17. API decisions
Command Objects accepts input JSON < Magic happens

18. API decisions
Command Objects accepts input JSON < Magic happens

19. API decisions
Command Objects accepts input JSON < Magic happens
Binding Lists

20. API decisions
Data Oriented Design (RESTful)
over
Screen Oriented Design

21. Infrastructure decisions

22. Infrastructure decisions
PostgreSQL as our main database
● Open-Source and very mature
● Highly scalability
● Widely used

23. Infrastructure decisions
MongoDB as a secondary storage for denormalized data
● Optimize read and searches by storing documents
● Filter, sorting, querying
● Highly availability

24. Infrastructure decisions
MongoDB to store statistics and usage data
● Fire and forget model
● Map-reduce to extract the information

25. Infrastructure decisions
MongoDB for geolocalized data
● Great support of geolocalization
● Aggregation pipeline

26. Infrastructure decisions
Terracotta as a Hibernate second-level cache
and HTTP sessions
● Dual licensing (community and commercial)
● Problems scaling (on the community product)
● Decided to change to Redis

27. Infrastructure decisions
Releases upload to a Nexus repository
● Upload all the software revisions
● “release plugin” can manage this
● Could be easily automated for a continuous
delivery

28. Awesome Tools
«If I have seen further it is only by standing
on the shoulders of giants.»
Isaac Newton

29. Awesome tools
Java Melody Plugin
● Allows monitoring of requests and JVM state
● Saved us in several occasions

31. Awesome tools
Build Test Data Plugin
● Creates complex objects from your constraints

32. Awesome tools
Build Test Data Plugin
● Creates complex objects from your constraints

33. Awesome tools
Build Test Data Plugin
● Creates complex objects from your constraints
Check constraints and
relationships and creates
the necessary objects

34. PostgresSQL Extensions plugin
Awesome tools
● Disclaimer: created by @ilopmar & @alotor inside
Kaleidos
● Provides native access to PSQL native types:
HSTORE, Arrays, JSON...

35. PostgresSQL Extensions plugin
Awesome tools

36. Awesome tools
Platform Core plugin
● Asynchronous task is a bliss
● Maintained by the Grails-core team

37. Awesome tools
Platform Core plugin

38. Know your tools

39. Awesome tools
GPars
● Easy parallelization inside the Groovy core
● Provides DSL’s and an easy API to parallelize
expensive tasks
● Sometimes difficult to work with GORM

40. Awesome tools
GPars

41. Awesome tools
GPars
Five threads at the same
time

42. Awesome tools
GPars
we need a transaction within
the new thread

43. Awesome tools
Groovy Metaprogramming
● Sometimes the magic is fun :)
● We developed a system with metaprogramming to
easily create new types of notification

44. Awesome tools

45. Awesome tools
Grails & Spring
● Problem: we wanted different implementations in
development and “real” environments
● Examples: notifications, file storage...

46. Awesome tools

47. Awesome tools
Inject a generic “fileService”

48. Awesome tools
Alias the necessary bean
per environment

49. Difficult Challenges

50. Difficult Challenges
Migration Grails 2.1.5 → 2.4.4

51. Difficult Challenges
Migration Grails 2.1.5 → 2.4.4
● Upgrade Grails and it’s dependencies
● Package changes, API changes…
● DataBinding and Command objects changes

52. Difficult Challenges
URL’s internationalization
● Grails doesn’t support out-of-the-box multi-language URL’s

53. Difficult Challenges
Tests pollution
● With 1500+ tests if you’re polluting one of your
tests is a big issue
● If this happens to you check:
by @tednaleid
http://bit.ly/1FlJs75

54. Difficult Challenges
API Documentation
● There is no easy way to keep an up-to-date API
documentation with Grails REST support
● Our solution: the documentation as GSP’s allow us to
reuse certain common part’s (like messages structure)

55. Difficult Challenges
MongoDB Plugin
● Mongodb’s GORM plugin had unexpected
behaviour
● We finally decided to use the low-level API when
accessing MongoDB

56. Going Forward

57. Going forward...
● Currently the application is only available for
spanish users
● Decathlon is present in 27 countries
Travel abroad!

58. Going forward...
● Decathlon Sport Meeting will be opening their API
● We hope to create an application ecosystem
around the social network
Opening the API

59. Going forward...
● First application using DSM API
● Was done during the ΠWEEK
Sport Spot

60. Going forward...

61. See you on track!