Re: Cleaning a space

Dan Creswell wrote:
> Once Outrigger has "seen" a class with name X, it will assume all X's
> have the same structure, same for Blitz.
>
> As an aside, note that co-existence of multiple versions can be quite
> costly performance wise for matching etc.

This issue is one of the issues I wanted to explore with my
http://griddle.dev.java.net project.  With griddle, the "keys" are separated
from the "data".  Either can be marshalled objects, or not.  You can put an
executor into griddle which can read one type of object, and migrate it to
another, I suppose.

As Dan is alluding to here, there are multiple issues about who sees what
classloader, when, and how do you make an injected executor have a common
classloader hierarchy with received data or key values.

With a griddle kind of mechanism, you can use MarshalledObject data, and have
the executor (an evolver if you will), unmarshall the data values with a
classloader that it creates, and then change (up or down grade) that object to
another object using another codebase (whatever is visible when it creates new
MarshalledObject values), and write that back into the griddle.

There are numerous benefits that come from the simplicity of a Javaspaces
implementation with MarshalledObject values, including non-live codebases so
that you don't have the "lost codebase" problem with objects that become live,
and then are marshalled back for transport to another JVM.

With griddle's opporunity to use live code inside of the space, you can then
manage the codebase issues more directly and formulate an environment that
causes the right codebase annotations to be used.

Gregg Wonderly

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