[rules-users] Query for a fact, and concurrent rule execution

[Michael Anstis]

Does each quote validation exercise enrich the StatefulKnowledgeSession
with other facts that could influence validation of other quotes?

If not probably using a StatefulKnowledgeSession per HTTP request might be
more simple (with the KnowledgeBase as an application scoped variable).

Regarding retrieval of results, there are a couple of options that spring
to mind:-

   - Look at using a Global to collate results.
   - Look at using a Query (
   http://stackoverflow.com/questions/5872215/how-do-i-add-facts-to-working-memory-at-runtime-in-the-drools-drl-and-retrieve-t
   )

With kind regards,

Mike

On 2 May 2012 10:39, stelomax <stephen.lomax at mattelli.com> wrote:

> Hi,
>
> Please bear with me, I am relatively new to the world of Drools and have a
> question.  I am hoping it will be a simple issue.
>
> First let me frame my planned implementation at a high level.  I am hoping
> to use Drools as a real time service enabled quote validation tool.
>
> Facts representing products and attributes will be loaded into a stateful
> knowledge session upon boot (using a piece of Java that loads these as
> facts
> from our product DB).
>
> The front-end application will allow users to build up quotes consisting of
> quote lines that make references to these products.  Once the quote is
> built
> they will press a "Validate" button.  This will call a webservice that
> will:
>
> 1) Insert the quote details as facts into the knowledge session
> 2) Run a "rule flow" to validate the quote against the product facts
> 3) The rules will insert validation results as facts tagged against the
> quote
> 4) QUERY for the validation results
> 5) Retract the facts for the quote (inc validation results)
> 6) Send the validation results back as a response to the webservice call
>
> My first question is how to implement step 4 --> how to physically query
> for
> the validation results pertaining to that specific quote.  Any help here
> would be greatly appreciated.
>
> My second question relates to concurrency.  As this is a quote validation
> tool there will be multiple users validating quotes so we will get
> concurrent validation requests.
>
> What is the recommended manner of dealing with concurrent rule requests
> within a stateful knowledge session.  If 2 people attempt to validate a
> different quote at the same time we will have two quotes within the
> knowledge session together with all of the product facts.  Is drools
> capable
> of running two concurrent rule flows against the knowledge session, each
> referencing a different quote or would we need to instantiate 2 knowledge
> sessions, or even deal with the matter in a serial manner placing the 2nd
> quote validation flow on hold until the first completes?
>
> Any help/pointers would be great.  I am hoping someone out there has
> attempted to use Drools in a similar manner :)
>
> Many Thanks
>
> Ste
>
> --
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> Sent from the Drools: User forum mailing list archive at Nabble.com.
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