How We Moved SDKs to Kotlin Multiplatform

and saved the world (kind of)

Intros

Ashley Arthur

Software Dev Engineer

The brains behind the talk
@ishley30

Intros

Zachary Powell

Sr Android Developer Advocate Manager, DevRel

The one that gets to talk to you.
@DevWithZachary

Takeaways

Takeaways

Not another Kotlin Multiplatform code talk.

Takeaways

Real world example of a team building a library in Kotlin Multiplatform

Takeaways

Learn from the pain

• History of the SDK's
• Past attempts at codeshare

Takeaways

See the success!

• Main changes from old codeshare
• The SDKs now
• Suprising improvements

What are the Vonage Client SDKs?

What are the Vonage Client SDKs?

Android, iOS and JS SDKs

What are the Vonage Client SDKs?

Wrappers for the Vonage REST/WebRTC APIs

What are the Vonage Client SDKs?

Make it easier to use the Vonage APIs in a native friendly way

Developers are our world.

History Lesson

A long time ago in a tech company far, far away....

• Three native SDK's, Android, iOS, JS all separate
• Tough to test across all platforms
• New features written by three separate teams
• 3x the work to implement something new

Nexmo was bought by Vonage.

Rewrite!

Kotlin Multiplatform try 1

• JS team took a look at Kotlin Multiplatform at a VERY early stage
• They wanted to rebuild EVERYTHING in Kotlin Multiplatform
• This failed.
• But we still want shared code!

Enter C++

• Allowed for some codeshare
• Base level with platform specific code written on top.

Happy Codeshare! Right?!

No.

Or Not.

• Still had three separate code bases on top of the C++ layer
• C++ code wasn't accessible to all on the team.
• Very slow builds limiting release cadence

Rewrite!

But with what?

• Shared code, just better
• Share business logic, not low-level platform stuff

What options?

No. Please. No.

Rust

• Very powerful
• Good shared codebase option
• Doesn't solve binding issues.
• Tooling for native was relatively unknown.

Kotlin Multiplatform

• Also a very good option for shared codebase
• Bindings solved!
• Let's Prototype

Prototype

• December 2021, Perfect time to hide and build the prototype.
• Very careful about what to put into the shared code
• Kotlin Multiplatform for business logic. Platform specific code stays out!

Platform Specific

• Networking - HTTP client, WebSocket, WebRTC client.
• Platform specific exposed behind interfaces for Kotlin Multiplatform to access.

Prototype delivered!

And it worked!

Then drama!

Ashley dared to have a baby (congratulations)

Team members left

Team had to focus on bug fixing in the current SDK

But wait!

The team is reminded of the pain points

Ashley returns!

“Sod it let's do it” - Ashley

From Prototype to SDK

What needed to happen?

Focus had just been on iOS and Android, JS was needed as well!

I asked the team

What were the main changes?

Team had to learn Kotlin

mix of Android, iOS and JS devs

All in on Gradle

This made iOS devs sad.

Shift in tooling, moving to a new IDE

A lot of the team had been using their own preferred IDE/text editors for the shared C++ code.

Today!

Vonage Client SDK for Voice released!

iOS, Android and Javascript!

Coming Soon!

Vonage Client SDK for Chat!

iOS, Android and Javascript!

Lessons Learnt / Reflection

What changed?

Keep up to date with Kotlin updates

Language still getting large updates

Original pain point of consistency has been removed!

Write once for everywhere!

Platform code is just exposing the functionality

More time to work on improving the API contract and making the SDK a joy to use!

Everyone knows Kotlin, anyone can build a feature

unlike before with C++/SDK

Move to a Mono repo

Whole team synced across all platforms

We have tests!

Tests are the key to saving developers (which are our world!)

Go check out the SDKs

Coupon Code, €10 free credit: 23CDLIS10

developer.vonage.com

github.com/Vonage-Community/tutorials-client_sdk-ios-android-js

Thank you!

links.zpweb.site

github.com/devwithzachary/presentations