The document discusses the design of a microservice-based website for a coder community. It describes using an event-driven architecture where services communicate asynchronously by publishing and subscribing to events. New content is added by publishing events to a message queue. Services consume events and index or store content. On requests, services retrieve and return relevant data to the frontend through queries. This allows independent development and horizontal scaling of modular services.

1. a micro service story.

2. What’s the perfect website for a coder community?

3. - everybody can contribute
- home page: Welcome! Who are we?
- event pages: when do we meet / announcements
- services: TechRadar, forum, messaging
- apis: extension points for other communities
- content for coders!
What’s the perfect website for a coder community?

4. hub.coding.earth

5. When I post an URL
coding.earth shall
determine if it can handle it
extract content
(find related content)
(tag the content (automatically?) )
index the content
display the new content.
When I search for “ruby” on coding.earth
It shall
ask the index for “ruby” content
(apply location / personal / date context)
adjust the page accordingly

6. The naīve approach
A synchronous http web service

7. https://meetup.com/colei/events/123+ Add
persistence
Meetups
elasticsearch
POST url
{
url: https://meetup.com/colei/events/123
}
services
The naīve way
Service “gateway”
chooses the right service to talk to
TweetsArticles

8. https://meetup.com/colei/eve+ GO
persistence elasticsearch
services
The naīve way
Service “gateway”
chooses the right service to talk to
https://meetup.com/colei/events/123
Meetups TweetsArticles

9. /meetup/123
{
title: “summer hack”,
starts: “Aug, 3rd”
}
/groups/colei
{
title: “coding leipzig”,
town: “Leipzig”,
center: LatLng
}
https://meetup.com/colei/eve+ GO
persistence elasticsearch
services
The naīve way
Service “gateway”
chooses the right service to talk to
https://meetup.com/colei/events/123
Meetups TweetsArticles

10. /meetup/123
{
title: “summer hack”,
starts: “Aug, 3rd”
}
/groups/colei
{
title: “coding leipzig”,
town: “Leipzig”,
center: LatLng
}
any url here+ GO
persistence elasticsearch
New meetup: “Summer hack”
services
The naīve way
Service “gateway”
chooses the right service to talk to
Your url has been processed
Meetups

11. /meetup/123
{
title: “summer hack”,
starts: “Aug, 3rd”
}
/groups/colei
{
title: “coding leipzig”,
town: “Leipzig”,
center: LatLng
}
any url here+ GO
persistence elasticsearch
POST url
{
url: https://meetup.com/colei/events/123
}
New meetup: “Summer hack”
services
The naīve way
Service “gateway”
chooses the right service to talk to
Your url has been processed
Meetups

12. /meetup/123
{
title: “summer hack”,
starts: “Aug, 3rd”
}
/groups/colei
{
title: “coding leipzig”,
town: “Leipzig”,
center: LatLng
}
any url here+ GO
persistence elasticsearch
POST url
{
url: https://meetup.com/colei/events/123
}
New meetup: “Summer hack”
services
Service “gateway”
chooses the right service to talk to
Your url has been processed
Meetups
The naīve approach
A synchronous http web service
- requests keep synchonously running
- any failure in any service can break the request
- strong coupling between “request” and service
layer
- the gateway must choose an interface
understood by all services
- all services are chain-requested
→ hard to scale
→ what if more than 1 service can respond?

13. The micro service way
event driven services
1. adding data

14. Coordinator
server side discovery
persistence
Event stream
elasticsearch
client event stream
services
https://meetup.com/colei/events/123+ GO

15. Coordinator
any url here+ GO
persistence
Event stream
elasticsearch
NewUrl
https://meetup.com/colei/events/123
client event stream
services
+client request id
Http event→
POST url
{
url: https://meetup.com/colei/events/123
}

16. /meetup/123
{
title: “summer hack”,
starts: “Aug, 3rd”
}
/groups/217
{
title: “coding leipzig”,
town: “Leipzig”,
center: LatLng
}
Coordinator
https://meetup.com/colei/events/123+ GO
persistence
Event stream
Meetup.com
elasticsearch
services
NewUrl
https://meetup.com/colei/events/123
client event stream
POST url
{
url: https://meetup.com/colei/events/123
}
Event
service→
index→
mediumtwitter youtube

17. /meetup/123
{
title: “summer hack”,
starts: “Aug, 3rd”
}
/groups/217
{
title: “coding leipzig”,
town: “Leipzig”,
center: LatLng
}
Coordinator
persistence
Event stream
Meetup.com
NewContent
/meetup/123
Content: {...}
interface: date
elasticsearch
services
idx
service→
event→
https://meetup.com/colei/events/123+ GO

18. Coordinator
persistence
Event stream
NewContent
/meetup/123
Content: {...}
interface: date
elasticsearch
New meetup: “Summer hack”
client event stream
services
+client request id
url has been processed
client request id
→ event
frontend→
https://meetup.com/colei/events/123+ GO

19. /date/314
{
ref: /meetup/123,
starts: “Aug, 3rd”
}
persistence
Event stream
NewContent
/meetup/123
Content: {...}
interface: date
calendar
elasticsearch
NewContent
/date/312
interface: date
services
event
service→
index→
https://meetup.com/colei/events/123+ GO
Coordinator

20. Coordinator
persistence
Event stream
elasticsearch
client event stream
services
New calendar entry
“Summer hack”
→ event
frontend→
https://meetup.com/colei/events/123+ GO
NewContent
/date/312
interface: date

21. /date/314
{
ref: /meetup/123,
starts: “Aug, 3rd”
}
/meetup/123
{
title: “summer hack”,
starts: “Aug, 3rd”
}
/groups/217
{
title: “coding leipzig”,
town: “Leipzig”,
center: LatLng
}
Coordinator
eventbrite
persistence
Event stream
Meetup.comtwitter
NewContent
/meetup/123
Content: {...}
interface: date
calendar
elasticsearch
NewContent
/date/312
interface: date
client event stream
New meetup: “Summer hack”
services
New calendar entry
“Summer hack”
+client request id
Your url has been processed
client request id
NewUrl
https://meetup.com/colei/events/123
POST url
{
url: https://meetup.com/colei/events/123
}
https://meetup.com/colei/events/123+ GO

22. The micro service way
event driven services
2. getting data

23. services
persistence
frontend app
GET /
200 OK
{
“meetups.”: {
endpoint: ‘meetups.’,
<metadata>
},
“calendar.”: {},
...
}
micro frontends
Coordinator Service
discovery

24. services
persistence
<Meetup Groups> <Calendar>
frontend app
200 OK
{
“meetups.”: {
endpoint: ‘meetups.’,
<metadata>
},
“calendar.”: {},
...
}
<meetup-groups
service={{
endpoint: String
}}
/>
micro frontends
Coordinator
<calendar
service={{
endpoint: String
}}
/>
render
fetch→

25. services
/date/314
{
ref: /meetup/123,
starts: “Aug, 3rd”
}
/meetup/123
{
title: “summer hack”,
starts: “Aug, 3rd”
}
/groups/217
{
title: “coding leipzig”,
town: “Leipzig”,
center: LatLng
}
persistence
Meetups calendar
<Meetup Groups> <Calendar>
frontend app
Interface QueryContext
{
term: string,
location: LatLng,
daterange: [Date,?Date]
tags: string[],
language: Lang,
user: UserContext
}
Interface QueryContext
{
term: string,
location: LatLng,
daterange: [Date,?Date]
tags: string[],
language: Lang,
user: UserContext
}
Host: meetups.{}
GET /search
{
query
}
<meetup-groups
service={{
endpoint: String
}}
/>
Host: calendar.{}
GET /search
{
context
}
micro frontends
<calendar
service={{
endpoint: String
}}
/>
fetch
query→

26. services
persistence
Meetups calendar
<Meetup Groups> <Calendar>
frontend app
Host: meetups.{}
GET /search
{
query
}
200 OK
{
groups: {
title: ‘coding leipzig’,
events: […],
}
}
Host: calendar.{}
GET /search
{
context
}
200 OK
{
groups: {
title: ‘coding leipzig’,
events: […],
}
}
micro frontends
Respond
render→

27. services
/date/314
{
ref: /meetup/123,
starts: “Aug, 3rd”
}
/meetup/123
{
title: “summer hack”,
starts: “Aug, 3rd”
}
/groups/217
{
title: “coding leipzig”,
town: “Leipzig”,
center: LatLng
}
persistence
Meetups calendar
<Meetup Groups> <Calendar>
frontend app
GET /
Interface QueryContext
{
term: string,
location: LatLng,
daterange: [Date,?Date]
tags: string[],
language: Lang,
user: UserContext
}
Interface QueryContext
{
term: string,
location: LatLng,
daterange: [Date,?Date]
tags: string[],
language: Lang,
user: UserContext
}
Host: meetups.{}
GET /search
{
query
}
200 OK
{
groups: {
title: ‘coding leipzig’,
events: […],
}
}
200 OK
{
“meetups.”: {
endpoint: ‘meetups.’,
<metadata>
},
“calendar.”: {},
...
}
<meetup-groups
service={{
endpoint: String
}}
/>
Host: calendar.{}
GET /search
{
context
}
200 OK
{
groups: {
title: ‘coding leipzig’,
events: […],
}
}
micro frontends
Coordinator
elasticsearch
<calendar
service={{
endpoint: String
}}
/>

28. Deployments
Good luck getting this one right!

30. - many languages supported
- Go, Java, Node, PHP, Python, Ruby, Lisp, C#/.NET
- lots of resource services
- Elasticsearch, MongoDB, Maria, Postgres, Solr
- Redis, RabbitMQ, Varnish, InfluxDB, Kafka
- declarative service definitions
- apps services↔ services
- post deploy tasks
- scheduled tasks
- routing
- scale
You could use Kubernetes (or Heroku) but it’s way harder to setup &
maintain

31. https://{default}/":
type: upstream
upstream: "frontend:http"
"https://www.{default}/":
type: redirect
to: "https://{default}/"
"https://coordinator.
{default}/":
type: upstream
upstream: "coordinator:http"
"https://rssreader.
{default}/":
type: upstream
upstream: "rssreader:http"
"https://calendar.{default}/":
type: upstream
upstream: "calendar:http"
"https://tweets.{default}/":
type: upstream
upstream: "tweets:http"
elasticsearch:
type:
elasticsearch:6.5
disk: 1024
size: S
kafkastreaming:
type: kafka:2.2
disk: 1024

32. name: coordinator
type: nodejs:10
size: S
dependencies:
nodejs:
pm2: "^2.4.0"
web:
commands:
start: "PM2_HOME=$PLATFORM_APP_DIR/run pm2 start index.js --no-daemon"
locations:
"/public":
passthru: false
root: "public"
headers:
Access-Control-Allow-Origin: "*"
Access-Control-Allow-Methods: "GET, POST, PUT, DELETE, PATCH,
OPTIONS"
Access-Control-Allow-Headers: "X-Requested-With, content-type,
Authorization"
allow: true
rules:
.(css|js|gif|jpe?g|png|ttf|eot|woff2?|otf|html|ico|svg|json?)$:
allow: true
^/robots.txt$:
allow: true
relationships:
kafka: "kafkastreaming:kafka"
mounts:
"/run": "shared:files/run"
disk: 128

33. - deploys an isolated environment for every branch
- copies all services & data from parent environment
- on merge, all new resources are created on the parent
environment
onboarding couldn’t be simpler
local environment only needed for convenience
access your environment’s remote services with SSH tunnels

34. Much faster / flexible local development
Must be customized for your local setup (user rights, ports)
define one service for each app
Reuse base images / Dockerfiles

36. Use microservices when
- you need a distributed architecture
- you can foresee decoupled development teams
- you can afford the deployment and maintenance process
- and use really good tools for it
- you are aware that there’s no shared data
- you’re on your way to serverless architectures
- you want to go maximum polyglot

37. https://github.com/cod1ng-earth/coding-earth
https://hub.coding.earth/
https://platform.sh/
https://microservices.io
@stadolf

38. Thank You!
please contribute :)
cod1ng-earth/coding-earth