Re: [rules-users] Using Drools Fusion to compute overlaps of many intervals

See inline. On 14/08/2013, Raphael Jolivet <raphael.jolivet(a)gmail.com&gt; wrote: > Hi Drools guys. > > I just asked the following question on > StackOverlow< http://stackoverflow.com/questions/18219841/using-drools-fusion-to-comput... > > . > Could you please help : > > I am already using Drools to do some *preprocessing of an allocation > problem > * (resources vs operations). The operations are already time *intervals* > but > I did not need to leverage the Drools Fusion features yet. > > There is a new requirement for having some *attributes of my resources > changing over time*. > > I am willing to model this (the change of values over time) as *"events" in > Drools* and take advantage of Drools Fusion, in *Cloud* mode. > > Hence I will have to match those "dynamic" attributes events against my > operations (again declared as events in Drools fusion). This will require > Drools to *compute a great amount of intervals overlaps*. > > I have several questions : > > - I have found the *overlap* operator to be kind of counter-intuitive, > and to not actually process*overlap* as we usually describe it. The definition of temporal operators in Drools follows well-established research. The intent is to be able to pinpoint very specific relations, with more general or symmetric relations requiring disjunctions. > I would > expect [a;b] and [c;d] to overlap if *(b > c) and (a < c)*. Is there a > time operator for that ? There are only those described in the Fusion manual. > Or should I use a composition of several time > operators ? Basically: yes, but see below. > - Does Drools Fusion uses any kind of internal optimization for this > kind of problem ? Not anything beyond the optimization provided by Rete (or whatever algorithm the Engine uses). You can look at the implementations of the operators: it's a pretty straightforward set of comparison, although the operator parameters add a level of complexity. You probably should implement your specific concept of "overlap" as a custom operator. > Naively matching N intervals against M intervals would > require *0(N x M)* operations. I have found a way to go down to *(M x > log(M) + N x log(N))*, by sorting the intervals beforehand : Should I > prepare the pair of overlaps for Drools in advance ? You may have to design an approach that accumulates events as they occur, determining whether a new event is one that joins a set of overlapping events or not. > - Related to the previous question : Is there any benefit in this case > (in term of performances), of using *Drools Fusion* instead of *regular > Drools* together with conditions over timestamps and duration ? Drools Fusion *is* what you call "regular Drools". It is just a marketing curlicue, to put a tag on a relatively small set of features: timestamp/duration, temporal ops, windows, cloud/stream, and event expiry. But there's only one Engine. Especially temporal operators is just syntactic sugar. -W > > Thanks for your advice > Brgds, > > -- Raphael > _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users