[rules-users] Evaluating Rules

[Willem van Asperen]

On 12/18/2012 07:46 PM, jgauss wrote:
> Hi,
>
> I have a doubth about rules.
> Can I to evaluate a rule using a external source?, for instance a database
> or always is it with a statics conditions?
Hi,

I think best practice is to insert a global, for instance, if you have
an entity of the class:

|class AGlobalDataSource||{||
||
||  public Collection<SomeData> getSomeDataFeed||{||
||    ...||
||  }||
||}|

Then you insert the data source into the working memory global:

|

AGlobalDataSource dataSource = new AGlobalDataSource();
WorkingMemory wm = rulebase.newStatefulSession();
wm.setGlobal( "dataSource", dataSource );

|
Then you should be able to read from that global's properties, like:

|global AGlobalDataSource dataSource;||
||
||rule "test from data source"||
||    when||
||        SomeData( ) from dataSource.someDataFeed||
||    then||
||        // action||
||end|

Bear in mind that the engine does not know if any data from the data
source is changed and the rules need to be re-evaluated.

Regards,
Willem
>
> Thanks.
>
>
>
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