Software concept of distributing system :
To make a distributed system work, distributors based OS is required, They are of following two types :
DOS (Distributor OS)
NOS (Network OS)
Parameter |
DOS |
NOS |
1) system Image |
It hides the complexity from the user & gives the view of virtual uniprocessor, system image is better than NOS. |
It doesn't hide complexity from user and gives it of multi processor, system image is bad |
2) Autonomy |
Every machine should use same as due to some kind of dominators with same OS autonomy is bad. |
Every machine may use different as, autonomy is good |
3) Fault tolerance |
If one MC fails it is easy to migrate the processes as everyone are using sources, It is good due to homogeneous failures |
Due to heterogeneous environment failure of are node it would not be easier to migrate the process, it is bad due to heterogeneous environment |
4) Example |
Ubiquity Linux (apalic server) |
Ubiquity Linux window 200 ? |
5)
Middle ware : Neither NOS nor DOS qualifies as a good as and hence a middle ware is developed known as distributed computing environment.
It allows to use both the OS & extract the best features out of both the OS.