Re: [rules-users] sliding window question

Hi Wolfgang， Thanks so much! I will try the sliding window over the time. I also need to give the average reading over the last 30 seconds in the alert message. How would I do that? Thanks Lin > On Feb 27, 2014, at 1:01 AM, Wolfgang Laun <wolfgang.laun(a)gmail.com&gt; > wrote: > > The correct way to ascertain that something hasn't happened for > a certain interval must be based on "staking out" this interval. One > way is by means of two distinct events: > > when > $r1: Reading( reading >90 ) > $r2: Reading( reading > 90, this after[30s] $r1 ) > not Reading( reading <= 90, this after $r1 && before $r2 ) > then > > Clearly, this will only work if Readings arrive regularly, and you may > have a > certain amount of delay at the end. > > Another way would be to use a sliding window over time: > > when > not Reading( reading <= 90 ) over window:time( 30s ) > then > > Here's a snag, too: If there are no readings at all, you'll also get an > alert. > > And then you'll have to think about the seconds following the 30th > second: should another alert be emitted repeatedly... > > Most of the time, it's not an issue in CEP ;-) > > -W > > > > > > >> On 27/02/2014, lin.lin <lin.lin(a)comcast.net&gt; wrote: >> Hi, >> >> I tried to create a rule that gives an alert when a machine reading is >> high >> for 30 seconds. I modeled the machine reading input as events. The >> following is the rule: >> >> rule "rule1" >> dialect "mvel" >> when >> $rd1 : mReading( reading >90 ) from entry-point ReadingStream >> not ($rd2 : mReading (reading<=90 , this before [0s, 30s] $rd1 ) >> from entry-point ReadingStream ) >> then >> System.out.print ("alert: Reading high for 30 seconds \n"); >> end >> >> This does not detect detect the bad reading. However, If I changed the >> rule >> to be following (change second condition from "not" to "exists"), it >> detects >> all readings that are good. >> >> rule "rule1" >> dialect "mvel" >> when >> $rd1 : mReading( reading >90 ) from entry-point ReadingStream >> exists ($rd2 : mReading (reading<=90 , this before [0s, 30s] $rd1 ) >> from entry-point ReadingStream ) >> then >> System.out.print ("alert: Reading high for 30 seconds \n"); >> End >> >> >> Is this an issue in CEP or did I do something wrong? >> >> Thanks a lot! >> Lily >> >> >> >> -- >> View this message in context: >> http://drools.46999.n3.nabble.com/sliding-window-question-tp4028367.html >> Sent from the Drools: User forum mailing list archive at Nabble.com. >> _______________________________________________ >> rules-users mailing list >> rules-users(a)lists.jboss.org >> https://lists.jboss.org/mailman/listinfo/rules-users > _______________________________________________ > rules-users mailing list > rules-users(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/rules-users _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users