Drools: Firing a rule if a set of events has n distinct values for a property -


suppose have event type has 3 properties: constraint, common, , distinct. goal write rule in drools fires when subset of events exists meets following criteria:

  • events happened in last t seconds; and
  • events have known value constraint property; and
  • share unknown value common property; and
  • there @ least n different values distinct property

if rule fires, need set of participating events further processing.

how advise approach problem?

note 1: question similar link, , steve's answer there seems promising incomplete.

note 2: performance of essence. have developed rules task, reduce performance of whole rule-base dramatically, , unacceptable.

edit 1: current (poorly performing) solution looks this:

rule "" when     $event : event(constraint == constant_value)     $events : arraylist() collect(             event(constraint == constant_value,              common == $event.common)             on window:time( t ))     $distinctvals : set( size >= n ) accumulate(event($d : distinct) $events, collectset($d))     // process $events end

drools isn't meant used computations require repeated evaluations of potentially big set of facts. in such situation you'll have offload details java code. 

class collector {     string constraint;     string common;     list<event> events = ...; // or queue     map<string,list<event>> dist2events = ...;     int diversity;      public void addevent( event e ){         // 1. remove event sets x events older t         // 2. remove members of x dist2events,         //    delete map elements value list empty         events.add( e );         list<event> ofdistinct = dist2events.get( e.getdistinct() );         if( ofdistinct == null ){             ofdistinct = new arraylist<event>();              dist2events.put( ofdistinct );         }         ofdistinct.add( e );         diversity = dist2events.keyset().size();     } }   rule createcollector when     event( $constraint: constraint, $common: common )     not collector( constraint == constraint, common == $common )     insert( new collector( $constraint, $common ) ); end  rule addevent when     $event: event( $constraint: constraint, $common: common )     $collector: collector( constraint == constraint,                            common == $common,                            events not contains $event )     modify( $collector ){ addevent( $event ) } end  rule morethan when     collector( $constraint: constraint, $common: common,                $events: events,                diversity >= n )  // maybe when n-1 n?     ... process $events end

you'll have decide whether want rule fire when threshold n exceeded or whenever set changes while diversity >= n.

you might want add rule remove empty collectors.


Comments

Post a Comment

Popular posts from this blog

android - InAppBilling registering BroadcastReceiver in AndroidManifest -

i'm implementing inapp billing in android app. works well, however, i'm trying decouple broadcast receiver activity manifest. suggestion in android's trivialdrive sample: // important: dynamically register broadcast messages updated purchases. // register receiver here instead of <receiver> in manifest // because call getpurchases() @ startup, therefore can ignore // broadcasts sent while app isn't running. // note: registering listener in activity bad idea, done here // because sample. regardless, receiver must registered after // iabhelper setup, before first call getpurchases(). currently there's class extends broadcastreceiver : public class iabbroadcastreceiver extends broadcastreceiver { /** * intent action receiver should filter for. */ public static final string action = "com.android.vending.billing.purchases_updated"; private final iabbroadcastlistener mlistener; public iabbroadcastreceiver(iabbroadcastlistener listener) { m...
Read more

python Tkinter Capturing keyboard events save as one single string -

is possible store keyboard events 1 string? code below stores 1 char , prints it. card reader or bar code reader, contains collection of character/ string not 1 character @ time. goal save char pressed text variable. from tkinter import * root = tk() def key(event): text= event.char text+= event.char print ("pressed", text) def callback(event): frame.focus_set() print ("clicked at", event.x, event.y) frame = frame(root, width=100, height=100) frame.bind("<key>", key) frame.bind("<button-1>", callback) frame.pack() root.mainloop() currently, creating text variable , everytime key() function gets called, , text stores last character typed. you can define text module level variable , , use module level text inside key function - text = '' def key(event): global text text+= event.char print("pressed", text)
Read more

sql server - Why does Linq-to-SQL add unnecessary COUNT()? -

here tables: create table customer ( cid int primary key, name varchar(32) ) create table ord ( oid int primary key, cid int foreign key references customer, address varchar(20) ) here's linq-to-sql statement: var aaa = c in db.customer select new { c, o = c.ord.tolist() }; and here's inexplicable query generated linq-to-sql: select [t0].[cid] [cid], [t0].[name] [name], [t1].[oid] [oid], [t1].[cid] [cid2], [t1].[address] [address], (select count(*) [dbo].[ord] [t2] [t2].[cid] = [t0].[cid]) [value] [dbo].[customer] [t0] left outer join [dbo].[ord] [t1] on [t1].[cid] = [t0].[cid] order [t0].[cid], [t1].[oid] i want understand how rid of count(*) part. it's entirely uncalled for! linq needs count(*) in order determine number of entries returned o = c.ord.tolist() .
Read more