This presentation introduces a systematic approach to designing microservices using a visual language, beginning with the identification of requirements and distillation into messages that dictate service interactions. The methodology is illustrated through the process of developing a user registration system, breaking down the requirements into discrete messages like 'register-user' and 'confirm-email', which in turn inform the design of specific services handling registration and email confirmation. The discussion extends to the temporal and functional dynamics of microservice interactions, differentiating between synchronous and asynchronous, as well as consumed and observed messages, using a unique visual lexicon where hexagons represent microservices, solid and dashed lines denote synchronous and asynchronous communications, and arrow styles distinguish between message consumption and observation. The narrative further concretizes these concepts by outlining the design of a Node.js module search engine, showcasing how business requirements translate into a network of microservices handling search, indexing, and module detail presentation. The intricate web of service interactions is depicted through the visual language, demonstrating how services like 'web', 'search', 'npm', and 'github' collaborate through well-defined message patterns. By the conclusion, attendees are equipped with a versatile framework for microservice design, capable of transforming complex system requirements into clear, manageable service components, as exemplified by the 'nodezoo' search engine project. This methodological approach not only clarifies the architecture of microservices systems but also facilitates their scalability, maintainability, and evolution over time.

1. Designing Microservices
A visual language
for service description
Richard Rodger
@rjrodger

2. How do you decide which
microservices to build?

3. Requirements
Messages
Services

4. "Build a user registration page"

5. Requirements
๏ a) capture user details
๏ b) send confirmation email

6. Requirements
๏ a) capture user details
๏ b) send confirmation email
Messages
๏ a) register-user: {name: ..., email: ...}
๏ b) confirm-email: {email: ...}

7. Requirements
๏ a) capture user details
๏ b) send confirmation email
Messages
๏ a) register-user: {name: ..., email: ...}
๏ b) confirm-email: {email: ...}
Services
๏ registration sends register-user to user
๏ user sends confirm-email to mailer

8. user registration mailer
register-user confirm-email

9. When do you need an answer?
๏Now: synchronous
๏Never: asynchronous

10. Who does the work?
๏One: message consumed
๏Many: message observed

11. micro-
service
A
micro-
service
B
solid line means synchronous
solid arrow means consumed
hexagons are microservices
synchronous/consumed
request-response

12. micro-
service
A
micro-
service
B
dashed line means asynchronous
empty arrow means observed
asynchronous/observed
publish-subscribe

13. micro-
service
A
micro-
service
B
solid line means synchronous
empty arrow means observed
synchronous/observed
sidewinder

14. micro-
service
A
micro-
service
B
dashed line means asynchronous
solid arrow means consumed
asynchronous/consumed
winner-take-all

15. Visual conventions
Service
Synchronous Message
Asynchronous Message
Consumed Message
Observed Message

16. "Message Abstraction Layer"
sender
receiver

17. Let's build a Search Engine
for Node.js modules...
Business Requirements:
๏ a) search for Node.js modules
๏ b) index published Node.js modules
๏ c) show Node.js module details

20. Requirements
๏ a) search for Node.js modules
Messages
๏ role:search,cmd:search (sync+consume)
Services
๏ web sends role:search,cmd:search to
search

21. web
search
role:search,cmd:search

22. Requirements
๏ b) index published Node.js modules
Messages
๏ role:search,cmd:insert (async+observe)
Services
๏ npm sends role:search,cmd:insert to
search

23. web
search
npm
role:search,cmd:search
role:search,cmd:insert

24. Requirements
๏ c) show Node.js module details
Messages
๏ role:info,cmd:get (sync+consume)
Services
๏ web sends role:info,cmd:get to info

25. web
search
npm
info
role:search,cmd:search
role:search,cmd:insert
role:info,cmd:get

26. Requirements
๏ c) show Node.js module details
Messages
๏ role:info,need:part (async+observe)
๏ role:info,collect:part (async+observe)
Services
๏ info sends role:info,need:part to npm,
github
๏ npm, github send role:info,collect:part to
info

27. web
search
npm
info
github
role:search,cmd:search
role:search,cmd:insert
role:info,cmd:get
role:info,need:part
role:info,need:part
role:info,collect:part
role:info,collect:part

29. Demo!

30. A search engine for
Node.js modules:
github.com/nodezoo
senecajs.org

31. bit.ly/taomicro
@taomicroservice

32. Thanks!
Richard Rodger
@rjrodger
richardrodger.com
senecajs.org

33. Thanks!
Richard Rodger
@rjrodger
richardrodger.com
senecajs.org