Comment isolation isn't enough (Score 1) 198
I read the arguments about Isolation - but sorry, isolation isn't enough.
To make things that never fail you need more than one computer!
The minimal configuration is TWO computers (sorry for shouting) and even that won't work if both computers fail.
This means you need to do distributed computing - whether you like it or not.
Stuff that never stops => more than one computer => distributed computing.
It also implies NO SHARED DATA STRUCTURES (imagine me hitting the keyboard here) - why? - think about it. Computer A has a pointer to a data structuire on computer B - computer B now crashes - ooops.
So how far have we come? - you need two or more computers, and no shared data structure (oh, and by the way, no sharing implies EVERYTHING MUST BE COPIED) - so you have to copy everything you need to do crash recovery to both machines involved.
This is very definately NOT how java was designed. Threads SHARE resources - so you have to use one style of programming when using two threads on the same machine but a completely different style of porgramming when using two threads on two different machines - some people might like this - I don't.
Oh and what more? - stable storage - what's that? Stable storage is storage which survives a crash! You need that as well.
I think (I'm not really sure) That there are actually 6 different things you need to do to make a fault tolerent system (see pages 27-28) of [1] - isolation in one of them.
If you want to make fault-tolerent system I'd suggest to read [1] (it's free) - then download [2] and off you go - it's easy.
Using [2] We have made some pretty reliable systems - as far as I know some of them have never stopped
Cheers
/Joe
