As an example, consider two different machines composed by service layers like in the diagram below:
- _________ _________
- | | replication | |
- | service |------------>| service |
- |_________| .------>|_________|
- | |----' | |
- |_________|------------>|_________|
-
- machine 1 machine 2
+ _________ _________
+ | | replication | |
+ | service |------------>| service |
+ |_________| .------>|_________|
+ | |----' | |
+ |_________|------------>|_________|
+
+ machine 1 machine 2
We can even consider that:
Layers can be even virtual: consider the equivalence of these two systems:
- _________
- | |
- | email |
- |_________| ____________
- | | | |
- | Zone | equivalence | OS / Email |
- |_________| --------------> |____________|
- | | | |
- | OS | | Machine |
- |_________| |____________|
- | |
- | Machine |
- |_________|
+ _________
+ | |
+ | email |
+ |_________| ____________
+ | | | |
+ | Zone | equivalence | OS / Email |
+ |_________| --------------> |____________|
+ | | | |
+ | OS | | Machine |
+ |_________| |____________|
+ | |
+ | Machine |
+ |_________|
Then, for a layer sit on top of one or another system there's not much difference in terms of property inheritance.