[jboss-jira] [JBoss JIRA] (JBRULES-2623) Decouple window definitions from pattern matching, allowing windows to be reused among various patterns/rules

[Edson Tirelli (Commented) (JIRA)]

    [ https://issues.jboss.org/browse/JBRULES-2623?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12639821#comment-12639821 ] 

Edson Tirelli commented on JBRULES-2623:
----------------------------------------

The initial goal of this work is to decouple window definition from window usage, allowing for different window types to be supported and reused among different rules. At this point, the goal is to support:

* *time based windows*, both strict and non-strict. I.e., for a window time(1h), support both immediate propagation and propagation only after the window is full.

* *length based windows*, strict and non-stritct. Support optional grouping expression. E.g. (pseudo-syntax):

{code:title=example.drl|borderStyle=solid}
// the following would create a window with the last 10 orders for each customer ID
@o : Order() over length(10, $o.customerId) 
{code}

* *batch time windows* (a.k.a., tumbling windows)

* *batch length windows* (a.k.a., tumbling windows)

At this point it is not clear yet if we can/should support modifiers "unique"/"distinct", "group-by" and "order-by".

Proposed syntax would be:

{code:title=drl.ebnf|borderStyle=solid}
windowDeclaration := 
DECLARE WINDOW id 
    annotation*
    lhsPattern
    (HAVING modifier)?
END

modifier := DISTINCT LEFT_PAREN expr RIGHT_PAREN 
{code}

E.g.:

{code:title=example.drl|borderStyle=solid}
declare window ticks
    @simple( test )
    $s : StockTick( source == "NYCE" ) 
         over window:length(5, $s.symbol) 
         from entry-point "stock tick stream"
end
{code}

The usage in regular rules would be supported as a new "from" construct:

{code:title=example.drl|borderStyle=solid}
rule X
when
    Company( $symbol : symbol )
    acc( StockTick( symbol == $symbol, $p: price ) from window ticks,
         $avg : average( $p ) )
then
    // the average price of the last 5 stock ticks for company $symbol
    // in the NYCE is $avg
end
{code}
 

                
> Decouple window definitions from pattern matching, allowing windows to be reused among various patterns/rules
> -------------------------------------------------------------------------------------------------------------
>
>                 Key: JBRULES-2623
>                 URL: https://issues.jboss.org/browse/JBRULES-2623
>             Project: Drools
>          Issue Type: Feature Request
>      Security Level: Public(Everyone can see) 
>          Components: drools-api, drools-compiler (fusion), drools-core (fusion)
>    Affects Versions: 5.1.0.FINAL
>            Reporter: Edson Tirelli
>            Assignee: Edson Tirelli
>              Labels: fusion_roadmap
>             Fix For: 5.4.0.Beta1
>
>
> Decouple window definitions from pattern matching, allowing windows to be reused among various patterns/rules.

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