Distributed System 3

Communication

Layered Protocol에서의 middleware protocol

책에선 크게 2가지로 분류를 해놓긴 함

1. Protocol that provides various middleware service (e.g. authentication, commit, distributed locking protocols)
2. High-level communication service(메세지 전송 그 이상을 해줌, kinda more specific) (e.g. RPC, Multimedia realtime, multicast service)

Communication types 분류

크게 3가지로 분류할수 있다.

1. Persistent vs Transient
   • Persistent Communication: Reciever가 깨어있지 않아도 middleware가 저장하고 있어서 message를 받을수 있어 (e.g. email)
   • Transient Communication: Reciever가 무조건 꺠어있어야 받을수 있어 (e.g. TCP, UDP)
2. Synchronous vs Async
   • Sync: 상대방의 응답을 기다려
     • 3 Synchronization points
     • 
       1. Middleware notifies that it will take over transmission
       2. Request has been delivered to the target recipient
       3. until its request has been fully processed
   • Async: 상대방의 응답을 기다리지 않아
3. Discrete vs Streaming Communication