[rules-users] Mapping complex objects info Guvnor compatible shim classes?

Sun Aug 11 17:22:14 EDT 2013

Drools Workbench (replacement for Guvnor) in 6.0 offers the ability to
easily add your own custom editors so you could provide your own UI to suit
your needs exactly.

It is much more difficult to add or replace editors in Guvnor 5.5 and early.

That said Rule Templates provide a means to define a rule, erm template for
want of a better word, that could be defined by more technically minded
users with others filling in the blanks.

Sent on the move
On 11 Aug 2013 21:11, "Mark Bennett" <mark.bennett at lucidworks.com> wrote:

 Thanks Steve.

 I'll check out dozer.

 I did look at DSL's, but the emphasis is really on putting a UI on things.

 Your advice on hold off baking in every single field also mirrors a point
that was raised on the team recently.  Advanced users can always drop into
DRL mode, etc.

 Actually, Guvnor's guided rules isn't our ideal UI either.  I think we
were hoping for more of a "wizard" toolkit where users select from a list
of pre-existing rules and fill in templates, at least as an option for new
users.  Then more advanced users could jump out to the guided rules or even
the expert / DRL rules mode.  But Guvnor's guided rules are still a pretty
advanced UI for newcomers.  It's kind of funny, I think people assume that
anything that has a "UI" is easy/obvious to use, even for new users; I'm
pretty sure we could all rattle off many counter-examples from the software
world. ;-)

 Any thoughts on conjuring a simpler UI for truly "guided" rules creation?
 I read that Guvnor could be embedded, but not sure that really helps
either.

--
Mark Bennett / LucidWorks: Search & Big Data / mark.bennett at lucidworks.com
Office: 408-898-4201 / Telecommute: 408-733-0387 / Cell: 408-829-6513

 On Aug 10, 2013, at 2:14 AM, Stephen Masters <stephen.masters at me.com>
 wrote:

 Your plan seems about right to me. When working in pure Drools, you don't
always need to do this. However, when working in Guvnor, I have always
found it necessary to create a simplified domain model for facts.

 In Guvnor, you can bind variables to fields and drill in, but it's fiddly.
Guided rules are much more readable when they are dealing with matching
bean-style facts with key attributes available through simple getX()
accessor methods. And of course you definitely need the bean-style getX()
methods.

 The other thing to think about, is that when working with Guvnor, you
should be avoiding any dependencies on external classes from within your
facts. Otherwise, you will need to put everything on your Guvnor web
server's class path, which totally messes with your ability to upload fact
model updates. Yet another reason to keep them simple.

 So given that you're going with that plan, here are my tips for the lazy
(like me)...

 To help with simplifying your transformations, it may be worth looking at
Dozer or similar: http://dozer.sourceforge.net/

 Personally, because I have often found that I'm doing things like mapping
multiple objects into a single fact, I tend to just do the mapping in
straight Java code. It tends not to be too painful, as I rarely find the
need for bi-directional mappings. I don't often need to get a fact back out
of working memory. So although it feels a bit naughty, I often avoid the
fact-to-domain-object transform. :)

 Think about what properties you really might want to write rules about.
It's easy to spend a huge amount of time writing a huge fact model, and
transforms for every single property of every class in your domain model.
Truth is you probably won't write rules that look at all of it. So have a
think about whether you do need to map everything or not. My tip here would
be to follow a TDD approach. Look at what rules your users want to write.
You should find that the rules mostly follow certain stereotypes, so create
rule tests covering a representative selection of such stereotype (ensure
coverage of all unique fact attributes which are examined). Create a fact
model which can satisfy those tests. Create tests for transforming from
your domain model to your fact model. Create transforms to that fact model.
Assuming you have a reasonably iterative environment, you can add
transforms for additional attributes when users have tried out the
application and come up with new rule stereotypes they would like to work
with.

 As an alternative (or to complement the above), take a look at DSLs. Each
DSL phrase becomes available in your guided editor, so you can have simple
rule phrases which the users can understand, but underneath, you can have
code which is drilling into nested objects.

 I do hope that's helpful… :)

 Steve

 On 10 Aug 2013, at 00:47, Mark Bennett <mark.bennett at lucidworks.com> wrote:

We want our domain experts to be able to create Guided Rules in Guvnor (5.5)

But Guvnor seems pretty limited about what it will accept, and how it will
render it.

We're attempting to create adapter classes that will:
* Allow us to expose a rich set of fields and methods in UI
* Use as injected facts into the engine

Main issues we're having:
* Native objects are nested, but Guvnor seems to want shallow
* Our native objects can have different attributes (different schemas)
- And you can't say getField( fieldName )
* Some returned items can be multivalued, vs. singular

Our idea is:
* Have admin send a prototypical request & schema event into our native
system
* Scrape and flatten that into a java class that exposes Guvnor friendly
methods
* Send that class into Guvnor
* Keep a copy of that class to create instances of when injecting facts
into the engine

Is there some type of easy way to map complex objects to/from the simpler
Guvnor/Drools model?  Some type of reflection based mapper with some simple
rules or a template?  We're wondering what others have done in this
situation?

Thanks,
Mark

--
Mark Bennett / LucidWorks: Search & Big Data / mark.bennett at lucidworks.com
Office: 408-898-4201 / Telecommute: 408-733-0387 / Cell: 408-829-6513

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