Airbnb had a successful migration to microservices, but managing hundreds of services made new challenges. The dependency graph is too complicated impacting scalability, reliability and velocity. Learn how we are evolving our read path service architecture to continue scaling our business.

1. How to Tame
Your Services:
Evolving Airbnb’s
Architecture
Jessica Tai / 5 March 2020 / ScaleConf

2. @jessicamtai

3. @jessicamtai

4. @jessicamtai

5. San Francisco
@jessicamtai

6. Scaling our engineering team
Beijing
San Francisco
Portland
New York City
MontrealSeattle
Los Angeles
San Jose
@jessicamtai

7. Hi. I’m Jessica.
I pair program with my Corgi dog.
@jessicamtai

8. Agenda
Architecture history
Monolith
Scaling challenges
Services
SOA v2 patterns
Abstraction
Lessons learned
Takeaways
@jessicamtai

9. Agenda
Architecture history
Monolith
Scaling challenges
Service
SOA v2 patterns
Abstraction
@jessicamtai
Lessons learned
Takeaways

10. Agenda
Architecture history
Monolith
Scaling challenges
Services
SOA v2 patterns
Abstraction
@jessicamtai
Lessons learned
Takeaways

11. Agenda
Architecture history
Monolith
Scaling challenges
Services
SOA v2 patterns
Abstraction
@jessicamtai
Lessons learned
Takeaways

12. Growth, growth,
growth!
Vanja Josifovski, Airbnb Homes CTO
“
@jessicamtai

13. SOA V2SOA V1Monolith
2008 - 2016 2016 - 2019 2019 - present
Airbnb architecture phases
@jessicamtai

14. SOA V2SOA V1Monolith
2008 - 2016 2016 - 2019 2019 - present
Airbnb architecture phases
@jessicamtai

15. SOA V2SOA V1Monolith
2008 - 2016 2016 - 2019 2019 - present
Airbnb architecture phases
@jessicamtai

16. Monolith
2008 - 2016
@jessicamtai

17. Monorail,ourRubyonRailsmonolith
@jessicamtai

18. Architecture pre-2016
Monolith
Client traffic
Shared
database
Monorail
Data access query
Business logic
Presentation view
@jessicamtai

19. Architecture pre-2016
Monolith
Client traffic
Shared
database
Monorail
@jessicamtai

20. Moreincidents Slowerdeploytrains
@jessicamtai

21. Moreincidents Slowerdeploytrains
@jessicamtai

22. SOA v1
2016 - 2019
@jessicamtai

23. Architecture 2016
Service-oriented arch (SOA)
API traffic
Routing & view
Business logic, model, data
via services
Client traffic
@jessicamtai
Monorail

24. Architecture 2016
Service-oriented arch (SOA)
@jessicamtai

25. Architecture 2016
Service-oriented arch (SOA)
@jessicamtai
Data service:
Entity read and writes

26. Architecture 2016
Service-oriented arch (SOA)
@jessicamtai
Computed data
service:
Combines data
sources
for multiple contexts

27. Architecture 2016
Service-oriented arch (SOA)
@jessicamtai
Middle-tier service:
Complex business
logic

28. Architecture 2016
Service-oriented arch (SOA)
@jessicamtai
Presentation service:
Synthesize data for
web and mobile UI

29. Checkout presentation
@jessicamtai
Homes data
Validation
mid-tier
Pricing
computed data

30. Architecture 2018
Service-oriented arch (SOA)
API gateway
Middleware
Session data
service
Authentication
data service
Oauth data
service
Risk computed
data service
...
Request
context
Web rendering
service
HTML view
@jessicamtai
Routing
Presentation, logic, data

31. 2019
After 3 years of migration,
enforced “Monorail freeze”
@jessicamtai

32. @jessicamtai

33. SOA wins
Performance wins due to
parallelization of dependencies
@jessicamtai

34. SOA wins
Faster code deployment
@jessicamtai

35. SOA wins
Better guarded, reliable code
@jessicamtai

36. Scaling challenges
with SOA v1
@jessicamtai

37. @jessicamtai

38. @jessicamtai

39. @jessicamtai

40. Growth, growth,
growth!
Vanja Josifovski, Airbnb Homes CTO
“
@jessicamtai

41. @jessicamtai
Monorail
Data access query
Business logic
Presentation view
Monorail mapped to SOA v1

42. @jessicamtai
Monorail
Data access query
Business logic
Presentation view
Monorail mapped to SOA v1

43. @jessicamtai
Monorail
Data access query
Business logic
Presentation view
Monorail mapped to SOA v1

44. Monorail mapped to SOA v1
@jessicamtai
Monorail
Data access query
Business logic
Presentation view

45. Data
Mid-tier
Mid-tier
DataData
@jessicamtai
Outgrowing SOA v1

46. Number of services at Airbnb
0
150
300
450
600
2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020
500+ engineers
2,000+ engineers
@jessicamtai

47. Challenges with SOA v1
Defect rate
Fragmented business
logic
Developer velocity
Too many
dependencies
New verticals
Scattered, custom
APIs & schemas
Scalability
Unguarded data
access
@jessicamtai

48. SOA v2
2019 - present
@jessicamtai

49. Slow developer velocity:
Too many dependencies
@jessicamtai

50. SOA v2 patterns:
Decompose
presentation services
@jessicamtai

51. SOA v1
Bloated presentation services
Presentation
UI logic
Data fetching
Business logic
@jessicamtai

52. SOA v2
Decompose presentation services
Presentation
UI logic
Data aggregation service
Business logic
@jessicamtai

53. @jessicamtai

54. Home highlights
@jessicamtai

55. Presentation
UI logic
A) Server-driven UI:
Display layout of home highlights
@jessicamtai

56. Presentation
UI logic
Data aggregation service
Reviews UserHomes
B) Aggregate data:
homes, reviews, user data stores
@jessicamtai

57. Presentation
UI logic
Data aggregation service
Business logic
DataData
C) Apply business logic:
Rank top highlights
@jessicamtai

58. Lack of scalability:
Unguarded, suboptimal access to data
@jessicamtai

59. SOA v2 patterns:
Aggregator
@jessicamtai

60. DataDataData
@jessicamtai
[SOA v1] No access control
Any service can call any other service

61. Presentation
Data DataData DataDataData
Data aggregation service
@jessicamtai
[SOA V2] Aggregator

62. {
reservation {
checkin_date,
guest {
first_name,
picture
},
host {
first_name,
picture
},
}
}
@jessicamtai
[SOA V2] Aggregator
Data aggregation service
Resolver Resolver Resolver
Map fields to
data source

63. Data aggregation service
{
reservation {
checkin_date,
guest {
first_name,
picture
},
host {
first_name,
picture
},
}
}
Resolver Resolver Resolver
Map fields to
data source
@jessicamtai
[SOA V2] Aggregator

64. Data aggregation service
{
reservation {
checkin_date,
guest {
first_name,
picture
},
host {
first_name,
picture
},
}
}
Resolver Resolver Resolver
Map fields to
data source
@jessicamtai
[SOA V2] Aggregator

65. Data aggregation service
{
reservation {
checkin_date,
guest {
first_name,
picture
},
host {
first_name,
picture
},
}
}
Resolver Resolver Resolver
Map fields to
data source
@jessicamtai
[SOA V2] Aggregator

66. [SOA V2] Aggregator
Data aggregation service
{
reservation {
checkin_date,
guest {
first_name,
picture
},
host {
first_name,
picture
},
}
}
Resolver Resolver Resolver
ServiceService
Batch fetch
fields
@jessicamtai

67. Migration to aggregator
Presentation
Data DataData DataDataData
Data aggregation service
API unchanged
@jessicamtai

68. Poor defect rate:
Scattered, duplicated business logic
@jessicamtai

69. SOA v2 patterns:
Computed data as a
platform
@jessicamtai

70. @jessicamtai
“Superhost” status
•# of reservations
•High review ratings
•No cancellations

71. Service
[SOA v1] Fragmented computed data
Superhost example
Reservations
data service
@jessicamtai
Reviews data
service
Cancellations
data service
Client
Service

72. Superhost example
Owned by
separate teams
Reservations
data service
Reviews data
service
Cancellations
data service
@jessicamtai
Client
[SOA v1] fragmented computed data
Service
Service

73. [SOA v2] Computed data as modular platform
Superhost example
Client
Computed data
platform service
Reservations
data service
Data source config
Data attribute Source
A Reservations
B Reviews
C Cancellations
@jessicamtai
Reviews data
service
Cancellations
data service

74. [SOA v2] Computed data as modular platform
Superhost example
Computed data
platform service
Data source config
Business logic lambda
boolean isSuperhost(A, B, C) {
return A && B && C;
}
Reservations
data service
@jessicamtai
Reviews data
service
Cancellations
data service
Client

75. Computed data as modular platform
Superhost example
Computed data
platform service
Offline pipeline &
index framework
A
B
C
Eventual
consistency
@jessicamtai
Client

76. Migration to computed data
Computed data
service
DataDataDataData
Compare responses
from codepaths
Service
Presentation
@jessicamtai
Offline
comparison
framework

77. Difficult to onboard verticals:
Custom APIs slow to navigate
@jessicamtai

78. SOA v2 patterns:
Service blocks
@jessicamtai

79. [SOA v1] Service blocks
@jessicamtai

80. [SOA v1] Service blocks
@jessicamtai

81. [SOA v1] Service blocks
@jessicamtai

82. Data aggregation service
Computed
Data DataData DataDataData
Logical grouping
of services
Presentation
UI logic
@jessicamtai
[SOA v2] Service blocks

83. Presentation
UI logic
Data aggregation service
Data DataData DataDataData
Logical grouping
of services
@jessicamtai
Computed
[SOA v2] Service blocks

84. DataData
Facade service
Computed
@jessicamtai
Computed
[SOA v2] Service blocks

85. Facade service
Unified API and schema
@jessicamtai
[SOA v2] Service blocks

86. Facade service
Service
Service
No internal block calls to services outside of the block
@jessicamtai
[SOA v2] Service blocks

87. Facade service Facade service
Presentation
UI logic
Data aggregation service
Service
Service
Service
@jessicamtai
[SOA v2] Service blocks

88. [SOA v2] Facade + computed data
Unified service
Computed data
platform
Facade service &
Presentation
UI logic
Data aggregation service
@jessicamtai

89. Migration to service blocks
Facade service
DataDataData
Computed
Data aggregation serviceClient service
@jessicamtai

90. @jessicamtai
Users
Homes
Pricing
Initial service blocks
Core domain entities

91. When to migrate?

92. Growth, growth,
growth!
Vanja Josifovski, Airbnb Homes CTO
“
@jessicamtai

93. SOA V2: Read path
computedFacade +
Presentation
UI logic
Data aggregation service
Service
Service
Service
computedFacade +
DataDataDataData
@jessicamtai

94. Pilot results
•Data aggregation service: 35% lower latency
[v1] Presentation service calls to data services
[v2] Single GraphQL query to aggregator
•Computed data platform: 30% faster engineer velocity
[v1] Implement in own service
[v2] Add to computed data platform
@jessicamtai

95. Design service architecture to
enable current growth needs.

96. @jessicamtai

97. @jessicamtai

98. @jessicamtai

99. @JESSICAMTAI
SCALECONF 2020