Server Server
Microservices:
Definition
> Independent deployment units
> E.g. process, VMs, Docker containers
> Any technology
> Any infrastructure
Micro
Service
Micro
Service
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Components Collaborate
Micro
Service
Micro
Service
Link
Data Replication
REST
Messaging
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Layered Microservices
iOS Android Web
Order Search Catalog
Billing
Customer
Backend Backend Backend
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Layered Microservices
> Reusable Backend Services
> Mobile client / Web App as frontend
> Backend for frontend (BFF): Custom
backend services
> ...to implement frontend specific logic
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Layered: Issues
> BFF might contain the same logic – same
processes
> BFF might contain most relevant logic
> Change to a business process means
changing many services
> Lots of communication
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Self-contained
System
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Deployment
monolith
Graphics by Roman Stranghöhner, innoQ
http://scs-architecture.org
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Cut Deployment
monolith along
domains …
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… wrap domain in
separate web
application …
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Self-contained
System (SCS) –
individually
deployable
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SCS =
user interface+
business logic+
data storage
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Each SCS contains all
layers.
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Self-contained
Systems
should be integrated
in the web interface
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Synchronous remote
calls inside the
business logic should
be avoided.
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Asynchronous Remote
calls reduce
dependencies and
prevent error
cascades.
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Every SCS brings its
own data storage
with its own
(potentially
redundant) data
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Domained scoped
SCS enables the
development,
operation and
maintenance of an
domain by a
single team.
Team 1
Team 2 Team 3
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1 SCS
= 1 Domain
= 1 Web App
= 1 Team
= 1-n Microservices
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Why create such a
complex system?
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Legacy Apps
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HTTP
New
Stuff
Links
No legacy code
Any technology
J
Small code base
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Sustainable
Development
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Monoliths
> Architecture rot
> …not maintainable any more
> …and can’t be rewritten / replaced
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Microservices
> Distributed system of small units
> Architecture violations harder
> Architecture won’t rot
> Small units
> Easy to replace
> Service rotten? Replace!
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Robust
> One failing Microservice doesn’t crash the
system
> However, Microservices must deal with
failing Microservices
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Continuous Delivery
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Principles behind the
Agile Manifesto
Our highest priority is
to satisfy the customer
through early and
continuous delivery
of valuable software.
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Deployment Monolith
ECommerce
System
3rd party
systems
Database
Build Pipeline for
Microservices
> Independent deployment
> Build pipeline per Microservice
> Smaller
> Easier to set up
> Less features (3rd party systems)
> Faster Feedback: Less tests
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Independent Scaling
> Can scale each Microservice
indenpendently
> Much easier than for a Deployment
Monolith
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Technology Freedom
> No meetings for introducing a bug fix in a
library!
> No big migration away from outdated
technology
> Easier experiments
> Higher motivation
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Scaling Agility
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Scaling Agility
> Do more
> Get more stories
implemented
> ...and running in
production
TODO IN PROGRESS DONE
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Scaling Agility
> Add more people
> Let the work in parallel
> Build more teams
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What is the problem?
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Communication
> Agile means communication
> Instead of written requirements
> ...story cards
> + direct communication
Challenges for
Scaling Agile
> Dependencies cause delays
> Too much communication about
functionalities,...
> ...releasing software,
> ...and technologies
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Challenges for
Scaling Agile
> Dependencies cause delays
> Too much communication about
functionalities...
> ...releasing software,
> ...and technologies
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Conway‘s Law
Architecture
copies
communication structures
of the organization
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Logic
UI
Database
Change
Order
Process!
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time
DB
Team Sprint
Logic
Team Sprint
GUI
Team Sprint
3 sprints
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Domained scoped
SCS enables the
development of a
domain by a
single team
– no coordination
Order Team =
UI+Logic+Database
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Challenges for Scaling
Agile
> Dependencies cause delays
> Too much communication about
functionalities...
> ...releasing software,
> ...and technologies
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