- to hide complex detail from the direct user
- most firm now used abstract distributive systems, such as AWS, Azure
Network Abstractions
- Remote procedure calls (RPCs)
- in distributive system, act as abstraction of remote procedure call in another address
The spectrum of failure models
Spectrum of consistency models
- Eventual consistency - sync after a finite time when no more write comes in
- ensures high availability
- Causal consistency - seperate into dependent and independent operation, preservers the order of the causally related operation
- display comment when it has been created
- Sequential consistency
- preserved the order of all client actions
- does not display changes instantaneously
- Strict consistency aka linearisability
- ensure any read operation would get the latest write values
- reduce availability
- such as account passwords