pt used at korean clojure seminar on 2017.11.11

1. replikativ
Building services without network API
(CRDT와 OTP를 중심으로)

2. re-frame
app-db components Hiccup Reagent VDOM React DOM
f1 f2 f3
eventhandler

3. re-frame
app-db components Hiccup Reagent VDOM React DOM
f1 f2 f3
eventhandler
Server

4. re-frame
app-db components Hiccup Reagent VDOM React DOM
f1 f2 f3
eventhandler
Server
● send/receive
● serialization/deserialization
● packing/unpacking
● error/exception handling
● routing

5. re-frame
app-db components Hiccup Reagent VDOM React DOM
f1 f2 f3
eventhandler
Server
● send/receive
● serialization/deserialization
● packing/unpacking
● error/exception handling
● routing
Compelexity!

6. re-frame
app-db components Hiccup Reagent VDOM React DOM
f1 f2 f3
eventhandler
Server
● send/receive
● serialization/deserialization
● packing/unpacking
● error/exception handling
● routing
Compelexity!Not Reactive

7. wanted
app-db components Hiccup Reagent VDOM React DOM
f1 f2 f3
eventhandler
Server
Reactive
Simple

8. wanted
app-dbServer
● 내가 데이타를 app-db에 쓰면 저절로 Server에 전달되었으면…
● Server에서 필요한 데이타가 저절로 app-db로 전달되어 있으면…

9. the problem is the networking
ClientServer
reactive c/s programming

10. ClientServer
Server
ServerServer
Server
Server
Client
Client
Client
Client
the reactivity of the distributed system
the problem is the networking

11. Hard Disk
Sector
File
Memory
Data,Time
Data FlowConceptial Layer
Implementation Layer
Physical Layer
Reactive
Programming
Imperative
Programming
Abstraction
Message,
Network API
???
One Machine Distributed System
Lan Electronic
Wiring
the problem is the networking

12. Leslie Lamport,
2013 Turing
Award Winner
● 논문 : Time, Clocks, and the Ordering of Events in a
Distributed System, 1978
● “Most people view concurrency as a programming
problem or a language problem. I regard it as a
physics problem” - Interviewed by Erik Meijer
● Yes, the problem is the networking.
● But it is not a programming or a language problem
but a physics problem.
the problem is the networking
the transition of problem domain

13. ● handled by mathematics
○ game
○ AI
○ Algorithms
○ CSP
● how does the network problem be handled by math?
the problem is the networking
the physics problems

14. Marc Shapiro
● 논문 : Conflict-Free Replicated Data Types, 2011
● a data structure which can be updated independently
and concurrently without coordination between the
replicas
● use
○ Riak : NoSQL
○ Roshi : SoundCloud
○ Game : Angry Birds, Leage of Legends
○ TomTom : navigation data sync
○ akka distributed data
CRDT

15. The messages is
● Delayed
● Dropped
● Delivered out-of-order
● Duplicated
이것은 프로그래밍 기술로 풀 문제가 아니다.
CRDT

16. The messages is
● Delayed ⇒ Associative
● Dropped
● Delivered out-of-order ⇒ Commutative
● Duplicated ⇒ Idempotent
CRDT

17. ● Associative
(A ● B) ● C = A ● (B ● C)
메세지를 어떻게 묶든 결과는 같다.
● Commutative
A ● B = B ● A
메세지가 순서가 바뀌어도 결과는 같다.
● Idempoent
A ● A = A
메세지가 중복되어도 결과는 같다.
CRDT

18. ● 수학의 한 분과인 순서론(Order Theory)중
부분순서집합인 Semilattice를 이용하여 CRDT의 존재를
증명.
● 메세지가 전달되는 순서에 관한 문제를 하나의 추상적
물리현상으로 보고 수학적으로 분석.
● 위상학(Topology)와 범주론(Category Theory)과 관련
CRDT

20. ● Counter
○ G-Counter
○ PN-Counter
● Register
○ LWW-Register
○ MV-Register
● Set
○ G-Set
○ 2P-Set
○ LWW-Set
○ PN-Set
○ OR-Set
● Map
○ ORMap
● Graph
○ DAG
● Array
○ RGA
CRDTs

21. ● OTP(Open Telecom Platform)
○ written in Erlang
○ used by Erlang
○ 미들웨어
● Erlang
○ nine-nineth의 고가용성의 concurrent, functional,
dynamically typed, and immutable language
○ Fault-tolerent
● Lightweight Process
○ 얼랭 프로그램을 구성하는 단위.
○ 프로그램은 얼랭 VM에서 관리
○ OS process도 thread도 아님
○ 어떤 자원도 서로 공유하지 않음.
○ 다만 메세지만 주고 받음.
○ Actor Model
OTP

22. ● Erlang’s Let It Crash Philosophy
● No Defensive Programming
○ Using exceptions and 'error handling'
adds complexity
● Supervisor/Worker
● 에러 발생하면 해당 process를 죽이고
재시작.
● Robust System
OTP
Supervisor
Worker

23. Hard Disk
Sector
File
Memory
Data,Time
Data FlowConceptial Layer
Implementation Layer
Physical Layer
Reactive
Programming
Imperative
Programming
Abstraction
Message,
Network API
CRDT,
OTP
One Machine Distributed System
Lan Electronic
Wiring
the problem is the networking

24. ● an open, scalable and distributive infrastructure for a
data-driven community of applications
● written in clojure.
● CRDT based.
● subprojects
○ kabel
■ pluggable, asynchronous nerwork IO
■ pub/sub architecture
○ konserve
■ pluggable, asynchronous storage IO
■ backend : CouchDB, Riak, LevelDB
○ superv.async
■ expand core.async
■ Erlang/OTP supervisor
■ Let It Crash
● 단 2명이 5년에 걸쳐 만듦
○ 완성도는 좋으나 아직은 실험적인 듯...
replikativ

26. replikativ

27. Demo