[rules-users] JPA persistence for Drools Flow

[Kris Verlaenen]

Quoting Marc Dzaebel <mdzaebel at web.de>:

> 
> Hi Kris,
> 
> thanks for your thorough and quite helpful explanation!
> 
> Kris Verlaenen wrote:
> > 
> > ... concrete plans in adding separate persistence of process
> instance
> > variables in the database. I expect this to be added to trunk in a
> few
> > weeks time. 
> > 
> So it could be in in Drools 5.0? I think the different strategies
> for
> process variables are exactly what we'll need. I'm glad to hear that
> standard use cases will be supported soon.

Probably not, Drools 5.0 is feature complete and should be released any
time now.  But we're planning to do much more smaller, incremental
releases now, so Drools 5.1 shouldn't be too long.

> 
> Kris Verlaenen wrote:
> > 
> > Another strategy ... is not querying on the runtime database but
> getting
> > the information from the history logs ... Notice that a history log
> is not
> > only about completed process instances, but about currently
> executing ones
> > as well.  The advantage of this approach is that queries on the
> history
> > log won't ever 
> > impact your running sessions and you can define what data to store
> > yourself 
> > (and how), optimized to your use case.
> > 
> This is a quite innovative idea and it sounds logical to reuse
> historical
> data and gain the aibility to save and query your data appropriately.
> It
> might slow down db access as you'll have to select the lastest
> version of an
> instance in advance (might be achieved by a simple flag). May be the
> combination of out-of-the-box process/variable persistence and
> customized
> historical persistence promisses the most benefit. However, we should
> work
> out patterns/examples of how to persist searchable processes.

Agreed, it does not work for all use cases of course.  Not sure what you
mean by "select the latest version of an instance" though, as there is
always only one version of a specific process instance (even in the
history log).  Note that the model of the history information is
different from the runtime model, and contains all the nodes that were
triggered (and possibly completed).  So new data gets added to this
process instance log every time something new happens, there's no
different versions there.

Kris 

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