Microservices promise a scalable architecture, increased flexibility, and better performance. But then you find out what’s actually involved in designing, developing, and running a microservices-based architecture. It turns out it’s not that straightforward after all. Often the discussion around microservices is framed by a false dichotomy between the messy monolith and the lean and mean microservices architecture. Sander Mak explains that there’s a third way: the modularized application. Functional decomposition of your application doesn’t imply that every component has to become its own independent process. Modularization is about strong encapsulation, well-defined interfaces, and explicit dependencies. Many languages offer in-process modularization features (for example, Java 9 with its upcoming module system), and there’s a strong overlap between the microservices philosophy and development benefits—without incurring the penalty of operational complexity. Sander explores the right (and wrong) reasons for going with a microservices architecture, as well as what a modularized application entails. You’ll see that splitting up an existing service or application into microservices isn’t always the clear winner. You’ll leave able to choose between the alternatives for the right reasons. There’s a place for both independently deployed microservices and larger applications with a strong internal modular structure. Choose wisely.

1. Modules or Microservices?
@Sander_Mak

2. About Sander
Fellow, Software Architect
@ Luminis
Experience in modular
development stacks
Conference Speaker & Author

3. @Sander_Mak
Modules or Microservices?

4. @Sander_Mak
Modules or Microservices?
YES

5. @Sander_Mak
Modules XOR Microservices?
YES

6. @Sander_Mak
Modules XOR Microservices?
IT DEPENDS

7. @Sander_Mak
Let's Talk About Modularity

8. Why Modularity?

9. Why Modularity?

10. Why Modularity?
No. 1 Software
Architecture Principle

11. @Sander_Mak
The Three Tenets of Modularity
Strong
Encapsulation

12. @Sander_Mak
The Three Tenets of Modularity
Strong
Encapsulation
Well-Defined
Interfaces

13. @Sander_Mak
The Three Tenets of Modularity
Explicit
Dependencies
Strong
Encapsulation
Well-Defined
Interfaces

14. @Sander_Mak
Modularity
is the ultimate
Agile Tool

15. @Sander_Mak
Let's Talk About Microservices

16. @Sander_Mak
A Microservice is...
Independently deployable
Implementing a business capability
Doing one thing, and doing it well
Communicating over the network

17. What's This?

18. What's This?
Microservices
Devroom

19. What's This?
Microservices
Devroom
Despair

20. What's This?
Microservices
Devroom
Despair
Praying for a
Better Solution

21. @Sander_Mak
Yes, Microservices Are Hard
However...

22. @Sander_Mak
Yes, Microservices Are Hard
However...
Introspection: When (not)

23. @Sander_Mak
Yes, Microservices Are Hard
However...
Introspection: When (not)
Alternative: Modules

24. @Sander_Mak
Why?
Manage Complexity
Scaling
Resilience

25. @Sander_Mak
Why?
Manage Complexity
Scaling
Resilience
Modularity
In Disguise!

26. @Sander_Mak
users
assignments
learningmaterial
students
grading
courses
attendance
Microservices

27. @Sander_Mak
users
assignments
learningmaterial
students
grading
courses
attendance
Microservices Monolith?
users
studentslearningmaterial
shipping
courses
forecasting
attendance

28. @Sander_Mak
users
assignments
learningmaterial
students
grading
courses
attendance
Microservices Monolith?
users
studentslearningmaterial
shipping
courses
forecasting
attendance

29. @Sander_Mak
Features
Cost

30. @Sander_Mak
Messy Monolith
Features
Cost

31. @Sander_Mak
Messy Monolith
Microservices
All The Way
Features
Cost

32. @Sander_Mak
Messy Monolith
Microservices
All The Way
Features
Cost

33. @Sander_Mak
Microservices:
Distributed system
Service Discovery
?
?
?
?
users
assignments
learningmaterial
students
grading
courses
attendance

34. @Sander_Mak
users
assignments
learningmaterial
students
grading
courses
attendance
Microservices:
Distributed system
Network Fallacies

35. @Sander_Mak
users
assignments
learningmaterial
students
grading
courses
attendance
Microservices:
Distributed system
Deployment

36. @Sander_Mak
Microservices:
Distributed system
Config. Management
v1
v2
v3
v2
v3
at least x4
(DTAP)
users
assignments
learningmaterial
students
grading
courses
attendance

37. @Sander_Mak
Microservices: Security
users
assignments
learningmaterial
students
grading
courses
attendance
Distributed system

38. @Sander_Mak
Messy Monolith
Microservices
All The Way
Features
Cost

39. @Sander_Mak
Messy Monolith
Microservices
All The Way
Features
Cost
But... vendors?!

40. @Sander_Mak
Messy Monolith
Microservices
All The Way
Features
Cost
But... vendors?!
Won't magically
transform your
organization!

41. @Sander_Mak
Let's Talk About Modules

42. @Sander_Mak
users
assignments
learningmaterial
students
grading
courses
attendance
Microservices

43. @Sander_Mak
users
assignments
learningmaterial
students
grading
courses
attendance
Microservices Monolith?
users
studentslearningmaterial
shipping
courses
forecasting
attendance

44. @Sander_Mak
Microservices Modules!
users
assignments
learningmaterial
students
grading
courses
attendance
Modular app users
assignments
learningmaterial
students
grading
courses
attendance

45. @Sander_Mak
Messy Monolith
Microservices
All The Way
Modular
App
Features
Cost

46. @Sander_Mak
Messy Monolith
Microservices
All The Way
Modular
App
Features
Cost

47. @Sander_Mak
So, Modules.
Did You Mean Objects?

48. @Sander_Mak
So, Modules.
Did You Mean Objects?
Close, but Too Fine-grained.

49. @Sander_Mak
Module Systems

50. @Sander_Mak
Module Systems
Java
OSGi
Java 9

51. @Sander_Mak
Module Systems
Java
OSGi
Java 9
JavaScript
...
ES2015 Modules

52. @Sander_Mak
Module Systems
Java
OSGi
Java 9
JavaScript
...
ES2015 Modules
C++
C++20?

53. @Sander_Mak
Module Systems
Java
OSGi
Java 9
JavaScript
...
ES2015 Modules
C++
C++20?
.Net
NuGet
.Net Core

54. @Sander_Mak
Explicit
Dependencies
Strong
Encapsulation
Well-Defined
Interfaces
Module Systems
Java
OSGi
Java 9
JavaScript
...
ES2015 Modules
C++
C++20?
.Net
NuGet
.Net Core

55. @Sander_Mak
Module Systems: Java 9
module attendance {
exports attendance.api;
requires students;
requires courses;
}

56. @Sander_Mak
Module Systems: Java 9
module attendance {
exports attendance.api;
requires students;
requires courses;
}
Strong
Encapsulation

57. @Sander_Mak
Module Systems: Java 9
module attendance {
exports attendance.api;
requires students;
requires courses;
}
Strong
Encapsulation
Well-Defined
Interfaces

58. @Sander_Mak
Module Systems: Java 9
module attendance {
exports attendance.api;
requires students;
requires courses;
}
Explicit
Dependencies
Strong
Encapsulation
Well-Defined
Interfaces

59. @Sander_Mak
Module Systems: Java 9
Module Resolution
(Reliable Configuration)
Increased Security
(Hide Platform Internals)

60. @Sander_Mak
Module Systems: ES2015
export function sq(i) {
return secret(i);
}
function secret(i) { return i * i; }

61. @Sander_Mak
Module Systems: ES2015
export function sq(i) {
return secret(i);
}
function secret(i) { return i * i; }
import { sq } from mymodule;
console.log("Two squared", sq(2));

62. @Sander_Mak
Module Systems: ES2015
export function sq(i) {
return secret(i);
}
function secret(i) { return i * i; }
Strong
Encapsulation
import { sq } from mymodule;
console.log("Two squared", sq(2));

63. @Sander_Mak
Module Systems: ES2015
export function sq(i) {
return secret(i);
}
function secret(i) { return i * i; }
Strong
Encapsulation
Well-Defined
Interfaces
import { sq } from mymodule;
console.log("Two squared", sq(2));

64. @Sander_Mak
Module Systems: ES2015
export function sq(i) {
return secret(i);
}
function secret(i) { return i * i; }
Explicit
Dependencies
Strong
Encapsulation
Well-Defined
Interfaces
import { sq } from mymodule;
console.log("Two squared", sq(2));

65. @Sander_Mak
Module Systems: ES2015
export function sq(i) {
return secret(i);
}
function secret(i) { return i * i; }
import { sq } from mymodule;
console.log("Two squared", sq(2));
Consider
TypeScript

66. @Sander_Mak
Module Systems: ES2015
export function sq(i) {
return secret(i);
}
function secret(i) { return i * i; }
Well-Defined
Interfaces
import { sq } from mymodule;
console.log("Two squared", sq(2));
Consider
TypeScript

67. @Sander_Mak
Module Systems: ES2015
export function sq(i) {
return secret(i);
}
function secret(i) { return i * i; }
import { sq } from mymodule;
console.log("Two squared", sq(2)); (let's not go there...)

68. @Sander_Mak
Module Systems: C++20?
module mymodule;
export int sq(int i) { return secret(i); }
int secret(int i) { return i * i; }

69. @Sander_Mak
Module Systems: C++20?
module mymodule;
export int sq(int i) { return secret(i); }
int secret(int i) { return i * i; }
#include <stdio.h>
import std.io
import mymodule
int main() {
printf("Two squared %d", sq(2));
return 0;
}

70. @Sander_Mak
Module Systems: C++20?
module mymodule;
export int sq(int i) { return secret(i); }
int secret(int i) { return i * i; }
#include <stdio.h>
import std.io
import mymodule
int main() {
printf("Two squared %d", sq(2));
return 0;
}
Strong
Encapsulation

71. @Sander_Mak
Module Systems: C++20?
module mymodule;
export int sq(int i) { return secret(i); }
int secret(int i) { return i * i; }
#include <stdio.h>
import std.io
import mymodule
int main() {
printf("Two squared %d", sq(2));
return 0;
}
Strong
Encapsulation
Well-Defined
Interfaces

72. @Sander_Mak
Module Systems: C++20?
module mymodule;
export int sq(int i) { return secret(i); }
int secret(int i) { return i * i; }
#include <stdio.h>
import std.io
import mymodule
int main() {
printf("Two squared %d", sq(2));
return 0;
}
Explicit
Dependencies
Strong
Encapsulation
Well-Defined
Interfaces

73. @Sander_Mak
So, Modules Everywhere!

74. @Sander_Mak
So, Modules Everywhere!
> Objects
< Applications

75. @Sander_Mak
users
app.users.User
app.users.UserInfo
app.users.internal.UserImpl
app.users.internal.Util;
assignments
...
...
courses
...
...
students
...
...
attendance
...
...
grading
...
...
learningmaterial
...
...
Not Just on the
Whiteboard

76. @Sander_Mak
users
app.users.User
app.users.UserInfo
app.users.internal.UserImpl
app.users.internal.Util;
assignments
...
...
courses
...
...
students
...
...
attendance
...
...
grading
...
...
learningmaterial
...
...
Not Just With
Discipline

77. @Sander_Mak
Modules or Microservices?
IT DEPENDS

78. @Sander_Mak
Manage Complexity
Scaling
Resilience

79. @Sander_Mak
Manage Complexity
Scaling
Resilience

80. @Sander_Mak
Manage Complexity
Scaling
Resilience
?
?

81. @Sander_Mak
Advantages of Modules
Ease of
Deployment &
Management

82. @Sander_Mak
Advantages of Modules
Ease of
Deployment &
Management
Modular Application

83. @Sander_Mak
Advantages of Modules
Strong but
Refactorable
Boundaries

84. @Sander_Mak
Advantages of Modules
Strong but
Refactorable
Boundaries
https://www.infoq.com/presentations/microservices-future
~1800 microservices

85. @Sander_Mak
Advantages of Modules
Strong but
Refactorable
Boundaries
"The [Linux] project is structured so
people can work independently,
Torvalds explained. "We've been
able to really modularize the code
and development model so we
can do a lot in parallel." - El Reg

86. @Sander_Mak
Advantages of Modules
Strongly typed,
In-Process
Communication

87. @Sander_Mak
Advantages of Modules
Strongly typed,
In-Process
Communication
No Serialization or Network Latency

88. @Sander_Mak
Advantages of Modules
Strongly typed,
In-Process
Communication
Ever Tried Serializing a Function?

89. @Sander_Mak
Advantages of Modules
Strongly typed,
In-Process
Communication
GraphQL or Protobuf > REST

90. @Sander_Mak
Advantages of Modules
Strongly typed,
In-Process
Communication

91. @Sander_Mak
Advantages of Modules
Strongly typed,
In-Process
*Synchronous*
Communication

92. @Sander_Mak
Advantages of Modules
Eventual
Consistency
is a Choice

93. @Sander_Mak
Advantages of Modules
Eventual
Consistency
is a Choice
It's Still a Good Idea to Partition Data

94. @Sander_Mak
Advantages of Microservices
Best Stack for Each Service

95. @Sander_Mak
Advantages of Microservices
Best Stack for Each Service
learningmaterial students assignments
(but is your org ready for this?)

96. @Sander_Mak
Advantages of Microservices
Independent Deployment
learningmaterial students assignmentsv2 v3 v1

97. @Sander_Mak
Advantages of Microservices
Independent Deployment
learningmaterial students assignmentsv2 v3 v1
(beware of deployment dependencies!)

98. @Sander_Mak
Advantages of Microservices
Independent Deployment
learningmaterial students assignmentsv2 v3 v1
Modularized App > Distributed Monolith
(beware of deployment dependencies!)

99. @Sander_Mak
Advantages of Microservices
Independent Failure
learningmaterial students assignments

100. @Sander_Mak
Advantages of Microservices
Independent Failure
learningmaterial students assignments
(when your services are truly autonomous...)

101. @Sander_Mak
Advantages of Microservices
Independent Scaling
assignments
learningmaterial
4x g2.2xlarge 2x t2.medium 1x t2.micro
students

102. @Sander_Mak
Advantages of Microservices
vs. Uniform Scaling
Modular Application
3x t2.large

103. @Sander_Mak
It's Time to Wrap Up

104. @Sander_Mak

105. @Sander_Mak
At the speed of light,
everything changes!

106. @Sander_Mak
At the speed of light,
everything changes!
Dude, chill. The apple still
doesn't fall far from the tree.

107. @Sander_Mak
Don't Solve Problems
You Don't Have
At the speed of light,
everything changes!
Dude, chill. The apple still
doesn't fall far from the tree.

108. @Sander_Mak
You Are (most likely) Not at
Uber or Netflix Scale
scale
organizations

109. @Sander_Mak
You Are (most likely) Not at
Uber or Netflix Scale
scale
organizations

110. @Sander_Mak
You Are (most likely) Not at
Uber or Netflix Scale
scale
organizations
the 80% of us

111. @Sander_Mak
Solve Problems You Do Have
In The Simplest Possible Way

112. @Sander_Mak
Solve Problems You Do Have
In The Simplest Possible Way
At Least Read Up on Modular Development
In Your Tech Stack of Choice
Explicit
Dependencies
Strong
Encapsulation
Well-Defined
Interfaces

113. @Sander_Mak
Design as Microservices,
Build as Modules
You Can Move to (Micro)services Later.

114. @Sander_Mak
Design as Microservices,
Build as Modules
You Can Move to (Micro)services Later.
Modules Enable
Larger Services!

115. @Sander_Mak
Design as Microservices,
Build as Modules
Don't worry, you can still do:
Reactive NoSQL Cloud DevOps DDD

116. @Sander_Mak
Messy Monolith
Microservices
All The Way
Modular
App
Features
Cost

117. Thanks. Read More:
bit.ly/modularapps
bit.ly/java9book
@Sander_Mak