designing a pragmatic back-end service for mobile games

Designing a Pragmatic Backend Service for Mobile Games

DK Moon (dkmoon@ifunfactory.com)

November 13 2013

Cliche: Mobile Game Segment Growing Super Fast

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

2013 2014 2015

Video Game Market Revenue Growth

Mobile Games Video Game Console PC Games

Source: Gartner (October 2013)

Game Development Ecosystem

GameServer

GameClient

Internet

Game Development Ecosystem

GameServer

GameClient

Internet

Game conceptGame logic designGame balance

Game Development Ecosystem

GameServer

GameClient

Internet

게임 기획자

Game conceptGame logic designGame balance

Game Development Ecosystem

GameServer

GameClient

Internet

게임 기획자

Game conceptGame logic designGame balance

Game graphic asset

Game Development Ecosystem

GameServer

GameClient

Internet

게임 기획자

Game conceptGame logic designGame balance

Game graphic asset

게임 그래픽 디자이너

Game Development Ecosystem

GameServer

GameClient

Internet

게임 기획자

Game conceptGame logic designGame balance

Game graphic asset

게임 그래픽 디자이너

Client app impl.Game logic impl.

Game Development Ecosystem

GameServer

GameClient

Internet

게임 기획자

Game conceptGame logic designGame balance

Game graphic asset

게임 그래픽 디자이너

Client app impl.Game logic impl.

소프트웨어 엔지니어

Game Development Ecosystem

GameServer

GameClient

Internet

게임 기획자

Game conceptGame logic designGame balance

Game graphic asset

게임 그래픽 디자이너

Server app impl.Game logic impl.

Client app impl.Game logic impl.

소프트웨어 엔지니어

Game Development Ecosystem

GameServer

GameClient

Internet

게임 기획자

Game conceptGame logic designGame balance

Game graphic asset

게임 그래픽 디자이너

Server app impl.Game logic impl.

Client app impl.Game logic impl.

소프트웨어 엔지니어

소프트웨어 엔지니어

Data center

DBServer

Game Development Ecosystem

GameServer

GameClient

Internet

게임 기획자

Game conceptGame logic designGame balance

Game graphic asset

게임 그래픽 디자이너

Server app impl.Game logic impl.

Client app impl.Game logic impl.

소프트웨어 엔지니어

소프트웨어 엔지니어

Data center

DBServer

Game Development Ecosystem

GameServer

GameClient

Internet

게임 기획자

Game conceptGame logic designGame balance

Game graphic asset

게임 그래픽 디자이너

Server app impl.Game logic impl.

Client app impl.Game logic impl.

소프트웨어 엔지니어

소프트웨어 엔지니어

Server mgmtServer monitoringLog analysis

시스템 엔지니어, DBA

Data center

DBServer

Game Development Ecosystem

GameServer

GameClient

Internet

게임 기획자

Game conceptGame logic designGame balance

Game graphic asset

게임 그래픽 디자이너

Server app impl.Game logic impl.

Client app impl.Game logic impl.

소프트웨어 엔지니어

소프트웨어 엔지니어

Server mgmtServer monitoringLog analysis

시스템 엔지니어, DBA

Who is the key player?

Mobile game is an entertainment business targeting end users.

Hence, game designer and graphic designer are important.• They determine look & feel. Also, game logic.

• But it assumes your engineers do not break anything.

Unfortunately, they will.

Engineers cannot guarantee success, but can lead to failure.• Software reliability is crucial.

• But very hard to find decent, experienced engineers.

Resource Requirement to Build a Mobile Game

Depending on game scale

• Casual games vs. mid-core games vs. hard-core games

If building a casual game…

• Around 300M KRW investment

• less than 10 members

• 6-9mo development

• 6-12mo service

Sorry, Buddy. Things Are Getting Worse.

Competition getting fierce

Need to design bigger games• More people & time. Hence, more cost…

Need to shorten time-to-market• More people. Again, more cost…

Efforts to Reduce Development Cycle

Client-side

• Relying on client engines (e.g., Unity3D, Cocos2D, …)

Server-side• Hardware: using IaaS cloud for server provisioning. (AWS)

• Software: leveraging web server technologies.

• Game features: Adopting external components/services.

(e.g., leaderboard, community)

Incompleteness of existing server-side solution

IaaS helps, but to a limited extent• Installing OS is not what engineers spend most of time.

• Converting into game server is the most time-consuming and error-prone.

Not all games are built on top of web server• HTTP works on a request-response basis.

Complex games require complex communication patterns.

• Web server is stateless in general. Even trivial operation should hit database.

Integrating into external service takes time.• Also gives learning curve.

Backend Service for Mobile Games

A set of hardware resources and software components accessible

via API to resolve issues in building mobile game server and related

infrastructure.

Mobile Game Backend Design Space

Infrastructure

Game server core

In-game components

Design Consideration #1: Infrastructure

Cloud storage

• For player profiles and game achievements

• Exposing DB interface vs. providing API?

Design Consideration #1: Infrastructure

IaaS

• Game developers manually configure machine.

• Tools are at the granularity of machine (CPU, RAM, Disk, Traffic, …)

• Bare-metal provisioning vs. VM provisioning?

Design Consideration #1: Infrastructure

PaaS

• Cloud instance is pre-configured as game server.

• Tools are at the granularity of game (#sessions, #items, …)

• Might include push server, player mgmt tools, etc.

Design Consideration #2: Game Server Core

Networking

• Message format (custom format vs. Protobuf/Thrift/JSON/…)

• Operating layer (session layer vs. transport layer)

• External integration (authentication, billing, …)

Design Consideration #2: Game Server Core

Database abstraction

• Explicit database calling vs. transparent database handling

Design Consideration #2: Game Server Core

Library vs. Framework

• Actively call into vs. Passively invoked.

Design Consideration #2: Game Server Core

Programming model

• Procedural vs. Event-driven vs. Declarative vs. …

Design Consideration #3: In-game Components

Components implementing game features

• Leaderboard, Chatting, Virtual currency, Matchmaking, AI

• Genre-specific in-game components

• …

Components architecture must be extensible• Tightly-coupled vs. loosely-coupled

• SDK approach vs. API approach

Short Survey on Backend Solutions

PlayerScale OpenKit Scoreoid Player.IOGoogle

(App Engine / Compute Engine)

In-game components

Yes(leaderboards, chat,

virtual currency, matchmaking)

Yes(leaderboards)

Yes(leaderboards, in-

game notifications, achievements)

Yes(lobby, chat)

Yes(leaderboards, achievement)

External integrationPayment

AuthenticationAuthentication Authentication

PaymentAuthentication

Analytics tools Yes Yes Only for error logs Yes

Cloud Storage Yes Yes Yes Yes Yes

Player management Yes Yes

Game server core Only for Flash

Infra support otherthan cloud storage

* Information gathered from official sites.

Short introduction on my work

Funapi

• Game server framework.

• Developers implement only game logic. Then, Funapi does the rest.

Argus• PaaS cloud specialized in mobile games

• Developers focus only on game server. Then, Argus does the rest.

Lessons from designing a backend service

Must be fool-proof

• Not all game developers share the same skills set.

• Do not blame game developers.

• If they fail, double-check if fool-proof.

Lessons from designing a backend service

Must be out-of-the-box

• Extremely tight time budget in game development.

• Do not expect game developers to eagerly go thru learning curve.

• If your backend service has high learning curve or

requires extensive integration work, it is less likely to be adopted.

Lessons from designing a backend service

Think deployment scenario from the beginning

• Extremely difficult to pull back once deployed.

• Versioning should be in place from the beginning.

• Package manager like Debian APT is worth referring to.

Questions?

dkmoon@ifunfactory.com