The document discusses lessons learned from developing a mobile game server engine. It emphasizes that system design and prioritizing goals are important. Initially, flexibility was prioritized over usability, but this led to high support costs. Balancing flexibility and usability is challenging. The developer adjusted the priority to focus more on usability by developing a programming model, networking framework, database handling, scaling architecture, and management interface. The system design for a game server engine is subtle and requires balancing flexibility to support different games with usability for developers.

1. 모바일 게임 서버 엔진 개발 후기
(그 당시 맞닥뜨린 선택의 문제들)
아이펀팩토리 문대경
dkmoon@ifunfactory.com

2. About the Speaker
✓ 1997: 제주도에서 상경한 컴퓨터공학도
✓ 1999-2005: 넥슨 서버팀에서 잡부계의 블루칩 등극
(입사 당시 서버팀 구성원: 김정주, 서민, 정상원, 박경국)
✓ 2005-2010: 외국 생활 해보고 싶다는 이유로 UC Berkeley 석사/박사
(Cisco, MS Research, Google 여름 인턴쉽)
✓ 2011-2012: Stock 을 포함한 Google 입사 제의 거절 후
Nicira Networks 라는 SDN 업체의 senior software engineer
(그 당시 Google 주가 $270. 현재 주가 $780)
✓ 2012-2013: Nicira 의 stock option 포기 후 넥슨 신기술개발실장
(넥슨 온지 몇 달 뒤에 Nicira는 VMware 에 $1.2B 에 피인수)
✓ 2013-현재: 아이펀팩토리에서 iFun Engine 개발 및 서비스

3. 걱정마세요.
오늘 물건 팔러 나온거 아닙니다.

4. Lifetime Lessons
✓ Strong implementation skills are necessary.
✓ But, system design is far more important.
✓ Prioritizing goals is the key to system design.
✓ Priority of goals shapes system’s strength and
weakness.

5. Back in July 2012

6. Goals Recap
✓ Flexibility: must support various genres
✓ Usability: must be easy to use
✓ Scalability: must seamlessly scale out
✓ Availability: must limit the impact of system failure
✓ Efficiency: must run with small resource footprint

7. Priority is Important
1.Flexibility: must support various genres
2.Usability: must be easy to use
3.Scalability: must seamlessly scale out
4.Availability: must limit the impact of system failure
5.Efficiency: must run with small resource footprint

8. Flexibility
Example: Nexon DOOMVAS
✓ Goal: share codebase among games
✓ Adopted in Nexon’s classic RPG games
• 바람의 나라, 어둠의 전설, 일랜시아, 아스가르드,
테일즈위버, 제라

9. Flexibility
Example: Nexon DOOMVAS
✓ Good try, but in practice…

10. Challenges in Flexibility
✓ Unclear boundary between common layer
and game layer
• “Legacy seems useless. I’d write from scratch.”
✓ Loose consensus quickly becomes
unmanageable as team grows
• Rookies always try to sabotage

11. Achieving Flexibility
Approach 1: by inheritance and overloading
• Pros: More transparent.
• Cons: Requires developers to know too much.
Hence, prone to error.
Approach 2: by hook registration
• Pros: Limits prerequisites.
• Cons: More restricted.
Hard to grasp the big picture.

12. Achieving Flexibility
Approach 1: by function overloading
• Pros: More transparent.
• Cons: Requires developers to know too much.
Hence, prone to error.
Approach 2: by hook registration
• Pros: Limits prerequisites.
• Cons: More restricted.
Hard to grasp the big picture.
2nd-level goal “Usability” as
tie-breaker

13. Wide-spread Misbelief
Game server engine = network engine

14. Wide-spread Misbelief
Game server engine = network engine
This is completely wrong

15. What Game Server Does?

16. What Game Server Does?

17. What Game Server Does?

18. What Game Server Does?

19. What Game Server Does?

20. What Game Server Does?

21. Rethinking Usability
✓ Must address challenges throughout
development cycle
• Networking is important, but not all
• Database handling is annoying
• Scaling out architecture is always challenging
• Invoking external service is common, but painful
• Mgmt interface seems overlooked, but must-have
• …

22. My Usability Set
Programming
Model
Network DB Scale-out
External
Service
Mgmt
• Framework
• Session-based
• TCP/UDP/HTTP
• Reliability
• ORM
• Caching
• Distributed
locking in ORM
• Server
discovery
• Unified interface
for auth, billing,
redis, …
• HTTP client
• HTTP server

23. Wait! No P2P?
✓ Mobile network (vs. wired) is omnipresence, and dominant
✓ Mobile (vs. wired) bandwidth is more scarce for frequency
✓ Hence, mobile telcos want more control over networks
✓ Unlikely to allow servers on mobile network. So little chance to
have P2P like PC online
✓ Relay can be a workaround, but can cause more network latency
✓ Note this is not only about mobile gaming. Mobile network is
becoming a commodity just like broadband did.
✓ And P2P has other very challenging issues like security, handover

24. Flexibility vs. Usability
✓ Initially, flexibility over usability.
✓ But found that less usability causes high
tech support costs
Flexibility Usability

25. Priority Adjustment
Usability
Flexibility

26. Summary
✓ System design is important
✓ Prioritizing goals is the key
✓ Game server engine design is subtle
✓ Balancing between flexibility and
usability is difficult

27. Thanks!
Questions?
dkmoon@ifunfactory.com