[rules-users] Dynamic facts

[Marc Heinz]

Hello everyone,

I need some enlightening about Drools "dynamic facts" (a term used in the
documentation, for facts that could be updated from outside the rule
engine).

The current documentation always list the "insert" method of a
StatefulKnowledgeSession being able to take an additional boolean
argument, stating that the corresponding fact supports the
PropertyChangeSupport related methods.

However, it seems that this method do not exists anymore for already some
time now...

After googling for a while it appears that some possible workaround were
modifyInsert (apparently removed from the API as well) and the
@propertyChangeSupport meta-data annotation, but I didn't manage to make
it work (actually I wasn't able to find any reference from it in the API,
so I guess that it is also not available anymore).

So, this left us with the "session.update" method. Which seems to works
great, except that it will invalidate the whole fact into the working
memory, even if only some of the fields were changed.

Is this some current limitation of Drools? Does it have something to do
with those "Shadows Fact"? (that would be somehow immutable?)

If we effectively can't fire update targeted to some specific fields, this
has probably some big implications on performances (even for simple fact
with only a few fields). It would also means that one should always aim at
the finest granularity for better performances, by somehow "flattening"
the object structure into the knowledge base (which in turn could make
complicated to reuse those same Pojo in other frameworks, such as
hibernate).

Did I miss something?

Any feedback deeply appreciated,

Thanks!

M. H.