Hello,
the idea of Linda tuple spaces is to have a passive central space where
clients can add or remove data. The client cannot invoke any server-side
execution. This programming model is very well suited for a wide range
of applications. But I'm asking myself whether it would make sense to
allow for some server-side execution for certain exceptional cases where
this makes sense. I guess this is some kind of perennial discussion ...
Let's give an example. Lately, I was prototyping a a little stm
framework. After a while I asked myself how to implement the commit of
a transaction. Well, you change some atomic variable for all affected
data in the transaction and then the new values become visible at once.
Then I asked myself how you would implement that when developing a
distributed stm system using JavaSpaces. The easiest way would be to
send the change list of the transaction to the server and execute the
code on the server-side to process the changes and change the atomic
variable when doing the commit. But this cannot be done, because there
is no way to spawn some server-side thread in JavaSpaces. Then, I have
to do the commit on the client-side. This will necessarily result in a
lot more traffic between the client and the central tuple space.
Now someone might say, that GigaSpaces or whatever system supports
optimistic locking and therefore to implement a distributed stm system
with GigaSpaces or whatever would be no problem. The point is here that
a distributed stm system is only an example of why server-side execution
might be justified in certain circumstances. You can find other examples
for things for which some JavaSpaces implementation has no direct
support and you are confronted with the same question whether there
should be an option to do some server-side execution in JavaSpaces.
So my point is merely "philosophical". If I were the owner of JavaSpaces
I would try to make sure that the clean and elegant programming model of
Linda tuple spaces won't fall apart and let things remain the way they
are. But the question whether some server-side execution makes sense
still bothers me. What do you think?
Regards, Oliver
www.objectscape.org
