Implementing API-First :
Practical Insights for Streamlining Your API
Alexandre TOURET
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Documenting our API ?
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The documentation
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Code-
First API-First
API-First to the Rescue
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Alexandre TOURET
Software Architect
@touret_alex
blog.touret.info
alexandre-touret
Who am I?
@touret.info
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We design payments technology
that powers the growth of millions
of businesses around the world.
7000+ engineers
in over 40 countries
Managing 43+ billion
transactions per year
€250M spent in R&D
every year
Handling 150+
payment methods
#1
European
payment
processor
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A customer point of view
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The « 3-Five rule »
5 seconds to
get into it
5 minutes to
test it
5 hours to
implement it
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Valuable
Credible
Desirable
Accessible
Usable
Findable
Useful
Empowering API
with UX!
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✓Being rapidly engaged with your API
✓A smooth integration
✓Get examples and accurate error management
Concretely… What it means for your
customers?
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The plan
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For our customers
• Provide a cohesive view
• Facilitate the integration
• Anticipate easily the new
functionalities
For us
• Avoid contract errors during the
implementation
• Remove boilerplate and useless code
• Streamline the development
API as a Product: Our goals
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• Pinpoint stakeholders
• Define the API in a functional
way first
Organization first
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• Define a set of standards & best
practices
• Ensure all the API work the same
An API Contract
API
Consumer Provider
Contract Contract
Consistency is key
Track & manage
your API portfolio
• The larger your platform
becomes, the harder it gets to
track API and their
dependencies
• Necessity to have a portal for
internal developers
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Tools
https://tools.openapis.org
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Store
Store all the assets into a Git
repository
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Build
Generate the changelogs
Pinpoint blocking changes
Generate code
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Validate
Use Merge request
Include tools to the pipeline
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Publish
Publish the API
1. Internally
• Portal using Docsy
• Artifact repository (e.g., Nexus)
2. Externally
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• Start validating your API first
• Fix it if needed
• Move it step by step to API First
What about the legacy?
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Revamping an application
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https://github.com/alexandre-touret/apifirst-sample
Example
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Wrap-up
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• Complexity of the OPENAPI specification
• The migration of the legacy is complicated
• Bugs & issues in the generated code
Difficulties & Drawbacks
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Stick to the
specifications
Better time to
market
Better quality
Streamline
development
Benefits
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• Guarantee the quality of your deliverables
• The documentation is part of the deliverables!
Developer Experience
Think from the customer's point of view!
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The function of good software is to
make the complex appear to be
simple.
– Grady Booch
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Don’t be a stranger!
Follow & get in touch
blog.worldline.tech
@WorldlineTech
Follow our tech team: Follow me:
@touret_alex
linkedin.com/in/atouret
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@touret.info
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