apidays LIVE Australia - Building Business Ecosystems From micro to macro-coordination through domain-centric DDL pipeline Alex Khilko, CTO of PlayQ Inc.

1. From micro to macro
coordination
Through domain centric DDL pipeline
Alex Khilko, CTO
PlayQ Inc.
Alex Khilko, CTO
PlayQ Inc.

2. API Days Live, From Micro to Macro Coordination, Sep 2020
PlayQ
2
Domain: Mobile Games
Distributed Team: California USA,
Ireland, Ukraine, Australia
Tech: Client and back-office facing
platform serving millions of players

3. API Days Live, From Micro to Macro Coordination, Sep 2020
PlayQ Platform
3
Areas Covered: Authentication, Analytics, Cloud Storage,
Real-time leaderboards, Payments, Ad-Networks & attribution
providers integrations, Push Notifications, Orchestration…
Term: 4 years in production
Languages:

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20+ High-performance services: 10-70ms response for the 99th
percentile
PlayQ Platform

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Services Team: 6 persons
PlayQ Platform

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Services API development

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API Design Breakdown
Business Logic
Domain Design
Dispatchers
Models & Codecs
Routing
Transport
If user A is of org B, then do C
There are entities: Users, Organizations
Logic execution dispatching
Entity representation: on the wire
Delivery routing: URIs, Path, Versions, ...
Delivery mechanism: HTTP, Sockets, ...
API

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Problems
1. Information is fragmented and decentralized Business Logic
Domain Design
Dispatchers
Models & Codecs
Routing
Transport
- Coming from multiple stakeholders
- Written and delivered using Confluence, Spreadsheets, emails,
etc.
- Ad-hoc requests
- Often times is incomplete, especially during design phase
API

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Business Logic
Domain Design
Dispatchers
Models & Codecs
Routing
Transport
- Entities are usually complex: hierarchical, relational
- Composition is not engineer friendly
API
Problems
1. Information is fragmented and decentralized
2. No solutions to map business domain to code

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0
Problems
1. Information is fragmented and decentralized
2. No solutions to map business domain to code
3. Most work is very mechanical and
time-consuming
Business Logic
Domain Design
Dispatchers
Models & Codecs
Routing
Transport- Once entities are designed, require a lot of mechanical work to reflect them in code
- Coordination with other teams / consumers to make sure implementation is
consistent
- Team interlocking
API

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Problems
1. Information is fragmented and decentralized
2. No solutions to map business domain to code
3. Most work is very mechanical and
time-consuming
4. Evolution and Refactoring is very error prone
Business Logic
Domain Design
Dispatchers
Models & Codecs
Routing
Transport
- Any change in the upper layers, has to be propagated down
- Any error in the upper layers, has to be fixed all the way
down
API

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Multiplied with every new consumer
Business Logic
Domain Design
Dispatchers
Models & Codecs
Routing
Transport
Business Logic
Domain Design
Dispatchers
Models & Codecs
Routing
Transport
Business Logic
Domain Design
Dispatchers
Models & Codecs
Routing
Transport
Business Logic
Domain Design
Dispatchers
Models & Codecs
Routing
Transport
API

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Solution
1. Single source of truth
2. Rich type system
3. Full reliance on code generation
4. CI/CD based changes propagation
https://izumi.7mind.io/idealingua/
API

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Single Source of Truth
API

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Rich Type System
package user.api
enum Role = Admin | Moderator | User
id EntityID {
uuid: uuid
}
mixin Entity {
id: EntityID
}
mixin Person {
name: str
surname: str
role: Role
}
data User {
& Entity
+ Person
password: str
}
data PublicUser {
+ User
- password: str
}
adt Result = Success | Failure
data Success {
message: str
}
data Failure {
code: int8
}
API

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Intuitive & Easy to read definitions
mixin Pet {
}
enum HuntingSkill {
lazy
clueless
}
/**
* A representation of a cat
*/
data Cat {
&Pet
/**
* The measured skill for hunting
* @default lazy
*/
huntingSkill: HuntingSkill
}
"Cat": {
"description": "A representation of a cat",
"allOf": [
{
"$ref": "#/definitions/Pet"
},
{
"type": "object",
"properties": {
"huntingSkill": {
"type": "string",
"description": "The measured skill for hunting",
"default": "lazy",
"enum": [
"clueless",
"lazy"
]
API
vs

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Full Reliance on Code Generation
mixin Person {
name: str
surname: str
role: Role
}
data User {
& Entity
+ Person
password: str
}
data PublicUser {
+ User
- password: str
}
API

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CI / CD Changes Propagation
mixin Person {
name: str
surname: str
role: Role
}
Change
CI / CD
API

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Authentication Service
API Example

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Providers support:
1. Support Email login
2. Support Google login
Auth Service

21. API Days Live, From Micro to Macro Coordination, Sep 2020
data LoginWithEmail {
email: string
passHash: string
}
data LoginWithGoogle {
accessToken: string
}
adt LoginRequest {
LoginWithEmail
LoginWithGoogle
}
21
Domain Models
data LoginResponse {
name: string
}
data GenericFailure {
code: int
message: string
}
service AuthService {
def login(data: LoginRequest) => LoginResponse !! GenericFailure
}
Auth Service

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Iteration 2 changes:
Add support for companyId, so we can have
multi-tenant deployment.
Auth Service

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Domain Models (rev 2)
mixin LoginWith {
companyId: CompanyID
}
data LoginWithEmail {
&LoginWith
email: string
passHash: string
}
data LoginWithGoogle {
&LoginWith
accessToken: string
}
adt LoginRequest {
LoginWithEmail
LoginWithGoogle
}
data LoginResponse {
name: string
}
data GenericFailure {
code: int
message: string
}
service AuthService {
def login(data: LoginRequest) => LoginResponse !! GenericFailure
}
Auth Service

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TypeScript Models Generated
mixin LoginWith {
companyId: CompanyID
}
data LoginWithEmail {
&LoginWith
email: string
passHash: string
}
Auth Service

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TypeScript Client Generated
service AuthService {
def login(data: LoginRequest) => LoginResponse !! GenericFailure
}
Auth Service

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// Client Definition
export declare class AuthServiceClient implements IAuthServiceClient {
login(data: LoginRequest): Promise<LoginResponse | BasicFailure>;
}
// Server Definition
export interface IAuthServiceServer<C> {
login(context: C, data: LoginRequest): Promise<LoginResponse | GenericFailure>;
}
TypeScript Client & Server Generated
Auth Service

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Iteration 3 changes:
Add support for 2-factor authentication during login.
Auth Service

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Domain Models (rev 3)
data LoginResponse {
name: string
}
data MfaRequest {
message: string
token: string
}
adt LoginResult {
LoginResponse
MfaRequest
}
data LoginWith2FA {
code: string
token: string
}
data GenericFailure {
code: int
message: string
}
adt LoginRequest {
LoginWithEmail
LoginWithGoogle
LoginWith2FA
}
service AuthService {
def login(data: LoginRequest) => LoginResult !! GenericFailure
}
Auth Service

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TypeScript Client Change
if (loginResponse instanceof MfaRequest) {
// TODO Ask user for a code and retry login
return;
}
// Successful, continue with execution
Auth Service

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Summary

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1. Roughly 60-70% of the code is generated (e.g. 250K generated
vs 95K actual business code in TypeScript codebase, 187K vs
120K in Scala)
2. We focus only on business logic and design
3. Every stakeholder contributes in an async way
4. No coordination on UserName or user_name when it comes to
actual implementation
5. Any API / Design change is immediately visible to all consumers
6. Refactoring is orders of magnitude easier
7. New APIs and changes through pull requests
8. Integration is a bliss and error free, no typos or missing data
Business Logic
Domain Design
Dispatchers
Models & Codecs
Routing
Transport
Summary

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Q & A
Alex Khilko
akhilko@playq.net

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Through evolution:
1. Add new services
2. Add new methods to existing services
3. Add new optional fields to existing models
4. Add new models
Through deployment address:
1. Version 1: /api/v1
2. Version 2: /api/v2
Through custom headers routing
Versioning

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1. Extensive primitive types, including Date, Time, DateTime with offsets, signed
/ unsigned numbers, and so on.
2. Unique algebraic and ID types
3. Definitions are parsed and AST is built using all of the inheritance, structural
composition information
4. Code is generated, not templated, making each language transpiler unique
and that follows semantics of the target language
5. Vertically sliced, making switching any layer an easy process: for instance
going from HTTP to WebSockets requires zero changes to the logic
6. Built-in support for HTTP and WebSocket transports, routing, JSON encoding
7. Server to Client requests system
8. Generated codecs tests
9. Converters: expand / contract are generated
Unique Features