API-first Redesign of a Legacy Application - Nordic APIs Platform Summit 2018

| API-first Redesign of a Legacy Application – Nordic APIs Platform Summit 2018 – Chris Busse - @busse
API-first Redesign of a Legacy Application
Nordic APIs - Platform Summit 2018
Chris Busse
CTO, APIvista
Richmond, Virginia
chris.busse@apivista.com
@busse | busse.io
Linkedin.com/in/chrisbusse
We’re hiring!
Richmond, Virginia, US
Raleigh, North Carolina, US

What is “API-first Design”?

•“Design-first” API Approach
•”Contract-first” API Design
•“API-first” Product Design

1979

Lemonade Stand Workshop,
a retrospective

What is a REST API?

“Resource manipulation through
representations”

(Switch to the Lemonade Stand Demo)
https://classicreload.com/lemonade-stand.html

What are the rules of the game?
(aka, the “business logic”)

Rules Given to the Player…

“Do we have enough information
to redesign this legacy app, API-
first?”

(Re-) Design
•Resources
•URL / URI
•Ontology
•Payloads
•Request / Responses
•Taxonomies
/customers
/customers/accounts
/customers/accounts/{number}/transactions
/…
/customers/{number}
{
firstName
lastName
emailAddress
...
}
1 2

http://lemonade-stand/???
Design
API Resources
/customers
/customers/accounts
/customers/accounts/{number}/transactions
/…
1

“Who wants to share?”

“I’ve been an Enterprise Software
Architect for 20 years….”

Open API Spec 2.0 | editor.swagger.io

http://lemonade-stand/???
Define
Payloads
/customers/{number}
{
firstName
lastName
emailAddress
...
}
2

“Are we sure we’re
on the right track?”

What did we learn about
approaching API-first Design?

We felt the User Journey and
Experience first-hand

Empathy

Design Validation:
Resilience to Change
“Add a cookie – not the browser kind!”
•You are going to sell cookies in the game now – what
changes in your API design?
•Which approach (items as resources, or turns) is
easier to handle this kind of change?

Database First or UI/UX First?
DBsDBs
DBs APIs UI/UX
Which should the API give precedence to in its design?

User Journeys take many
branching paths

Do you really need that right now?

YAGNI
(“You aren’t going to need it”)
YAGNIN
(“You aren’t going to need it now”)

So who decides?
The customer does, by intent.

Appropriate Abstractions

(aka “the Mulesoft way”)
Source: https://www.slideshare.net/HarishKumar544/three-layer-api-design-architecture

Thinking in Abstractions are
how you create resource
representations and
make REST not CRUD

Are you just refinancing your
technical debt?

What if we want to make this a real
API Product?

UX | DXUser Experience Developer Experience

Creating DX: Three Kinds of API Development
Database
Server
Framework
View (UI)
(Ex: MEAN stack development)
1: Self 2: Team 3: External

Database
Server
Framework
View (UI)
APIs

Database
Server
Framework
View (UI)
APIs
APIs

Database
Server
Framework
View (UI)
3: External
APIs
The lower in the software
stack you deliver APIs,
and the farther away the
consuming developer is,
the more empathy for
Developer Experience you
need to have

The question to ask candidates:
Have you built APIs for other
developers outside of your own
organization?

“There is no business problem that can’t
be solved by good recruiting”
- Karen Booth Adams

In summary…

API Developers should actively seek
to gain empath for the end-users of
the systems implementing their APIs,
and design accordingly

Let the real needs of the users
heavily inform backlog
prioritization

Abstractions can bring freedom, but
understand the trade-offs you’re
making when further burying
technical debt

Lean in and hire great
developers…

One of the best ways to help build
empathy for customers is to bring
more diversity into your dev and
product teams.

API-first Redesign of a Legacy Application
Nordic APIs - Platform Summit 2018
Chris Busse
CTO, APIvista
Richmond, Virginia
chris.busse@apivista.com
@busse | busse.io
Linkedin.com/in/chrisbusse
10 REM <<< LEMONADE STAND >>>
15 REM
20 REM FROM AN ORIGINAL PROGRAM
30 REM BY BOB JAMISON, OF THE
40 REM MINNESOTA EDUCATIONAL
50 REM COMPUTING CONSORTIUM
60 REM * * *
70 REM MODIFIED FOR THE APPLE
80 REM FEBRUARY, 1979
90 REM BY CHARLIE KELLNE

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