Building Better Software Faster

@aahoogendoorn | www.ditisagile.nlBuilding better software faster 1
@aahoogendoorn | www.ditisagile.nl
Building
better
software
faster
Sander Hoogendoorn
ditisagile.nl

Sander Hoogendoorn
Me
Dad, software architect, agile coach, programmer, trainer,
speaker, writer
Books, articles, conferences, courses
Work
Owner ditisagile.nl
CTO ANVA
Former CTO insurance company
Former global agile thoughtleader Capgemini
Web
www.sanderhoogendoorn.com
aahoogendoorn
aahoogendoorn
sander@ditisagile.nl

As a project manager
I would like to demo untested code so I embarrass myself

The Times They
Are a-Changin'

Moore’s Law
The number of transistors in a dense integrated circuit doubles approximately every two years.

The Times They
Are a-Changin'
On our block

Too much, too soon
Hard to deliver, harder to test, impossible to maintain

Dependencies will kill you

Microservices
A definition

Microservices
In short, the microservice architectural style is an approach
to developing a single application as a suite of small services,
each running in its own process and communicating with
lightweight mechanisms, often an HTTP resource API.
These services are built around business capabilities and
independently deployable by fully automated deployment
machinery. There is a bare minimum of centralized management
of these services, which may be written in different programming
languages and use different data storage technologies.
Martin Fowler

From the trenches
Microservices in real life

For the things we have to learn before
we can do them, we learn by doing
them
Aristotle

Microservices require
an evolutionary software architecture

Some guiding
principles
Business processes first

We implement business processes
We move towards a systems landscape consisting of
micro-applications and micro-components
Requirements are modeled (in smart use cases)
Micro-applications implement a single elementary
business process
Micro-applications and micro-components all have their
own bounded context
Micro-applications do not have storage, and only talk to
other micro-applications and micro-components
Micro-components have their own storage (in
MongoDB), and only talk to other micro-components
Communication uses a simple open protocol – JSON
on REST
We avoid transactions as much as possible
Some guiding principles

Smart use cases

Presentation
Process
Domain
Services
Outside world
Pages
Grids, Panels, Controls
Use cases
Flow
Factories, Repositories
Entities, Enums, Value objects
Gateways
ComponentsRelations Dossiers Intermediaries Accounts Rates

Service interface
Process
Domain
Data / Services
Outside world
Resources
Representations
Use cases
Flow
Factories, Repositories
Entities, Enums, Value objects
Gateways
StorageRelations Dossiers Intermediaries MongoDB

Designing
microservices
Modular design and
bounded contexts

Doing big up-front design is dumb,
doing no design up-front is even dumber
Dave Thomas

Bounded contexts

Single responsibility principle
Group together things that change together
Separate things that change for different reason

Bounded context
When you model larger domains, it becomes progressively
harder to create this single unified model.
Instead of creating a single unified model, you create
several, all valid within their bounded context

The single unified domain model
Or more often the humongous data model
Product
Vendor
Stock
Order
Client
Delivery
Payment

Bounded contexts
Product
Vendor
Stock
Order
Client
Delivery
Payment
Product

Testing
microservices
Failing fast

Fail fast, fail often, fail forward

Manual
tests
Scenario
tests
Integration
tests
Unit
tests

Manual
tests
Scenario
tests
API
tests
Unit
tests

A development lifecycle
What to test?
Code
Developer
Test
Test
Integration
Test
Acceptance
Test
Live
Prepare
and Design
Developers
Unit tests
Developers
Peer review
Testers
Scenario’s
And API’s
Testers
Scenario’s
and API’s
Product owner
Product

Even though you might have really brilliant testers…
Exploratory
Testing,
anyone?

Deploying
microservices
Continuous integration
and build pipelines

How often do you deploy to production?

A typical build pipeline
Code
Developer
Test
Test
Integration
Test
Acceptance
Test
Live
Prepare
and Design

ProductionAcceptanceIntegrationTestDevelopment
Traditional (virtual) infrastructure
Code
Developer
Test
Test
Integration
Test
Acceptance
Test
Live
Prepare
and Design

ProductionProvisionedProvisionedProvisionedDevelopment
Provisioned infrastructure (on the fly)
Code
Developer
Test
Test
Integration
Test
Acceptance
Test
Live
Prepare
and Design

Microservices
Building multiple deployment pipelines
Code
Developer
Test
Test
Acceptance
Test
Acceptance Live
Code
Developer
Test
Test
Acceptance
Test
Acceptance Live
Code
Developer
Test
Test
Acceptance
Test
Acceptance Live
Code
Developer
Test
Test
Acceptance
Test
Acceptance Live

Infrastructure as code

Agile
beyond
Scrum
Towards continuously
delivering software

Lowering our fences

Dogmagile

The red sprint anti-pattern

Minimal viable products
Think small, deploy early and frequently

Do we need this
NOW?

Roadmaps over plans
While there is value in the items on the right, we value the items on the left more

Continuous delivery
An approach in which teams ensure that every change to
the system is releasable, and that we can release any
version at the push of a button.
Aimed to make releases boring, so we can deliver
frequently and get fast feedback on what users care about.Jez Humble

In retrospective
Some final thoughts

The times are a-changin’
How are we going to keep up?
Towards
micro-applications
and microservices
Modeling
requirements
Focus on
core
technologies
Continuous
delivery
Minimal viable
products
Rationalize
our legacy
Domain driven
design
Leverage
the cloud

References
and questions
www.sanderhoogendoorn.com
www.ditisagile.nl
aahoogendoorn
aahoogendoorn
sander@ditisagile.nl

Building Better Software Faster

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