Hello, I'm having a problem using sliding windows length I would like to get the average oft he last 5 Events of the AccountNumber "123" (rule: FiveLastEventsWhichBelongsToTheAccount). If there are no Events with other AccountNumbers and if the AccountNumber is directly added as String as a rule constraint, both cases will work correctly as I understand the rule behaviour But If there are Events available for different AccountNumbers and the AccountNumber is extracted from the $account : Account() to use it as a constraint to check if the Event belongs to the AccountNumber the condition is not working like first filter then window; it seems to work like first window then filter) I don’t know if it should work like this or if it is maybe a bug. If I’m wrong, how is it possible to solve my problem, so that I don’t need to write a rule for every possible account number. Thanks in advanced Andreas I’m using drools version 5.3.5 because of the NPE ( https://issues.jboss.org/browse/DROOLS-78?page=com.atlassian.jira.plugin....), which don’t occurs in this test case but in other rules I’ve implemented. So it would be nice to have a solution for version 5.3.5. For Testing you can use the following classes and drl File: public class Account { private String number = ""; public Account() { super(); } public String getNumber() { return number; } public void setNumber(String number) { this.number = number; } } public class Event implements Serializable { private static final long serialVersionUID = 1L; private String accountNumber = ""; private double amount = 0.00; public Event(String accountNumber, double amount) { this.accountNumber = accountNumber; this.amount = amount; } public String getAccountNumber() { return accountNumber; } public void setAccountNumber(String accountNumber) { this.accountNumber = accountNumber; } public double getAmount() { return amount; } public void setAmount(double amount) { this.amount = amount; } } Rule file declare Event @role( event ) end rule "FiveLastEventsWhichBelongsToTheAccount" when $account : Account() $averageOfAmount : Number( doubleValue > 0 ) from accumulate( Event( //accountNumber == “123“, //works accountNumber == $account.number, //not working if more than one //AccountNumbers available during all events $amount : amount ) over window:length( 5 ) from entry-point EventStream, average($amount) ) then System.out.println("Average of aveOfLastClaims: " + $averageOfAmount); End TesterClass: public class Tester { private static final String DRL_FILENAME = "account.drl"; private static final String ENTRY_POINT = "EventStream"; private static KnowledgeBase knowledgeBase = null; private static StatefulKnowledgeSession session = null; private static Account account123 = null; private static String accountNumber123 = "123"; private static Account account456 = null; private static String accountNumber456 = "456"; private static void setUp() { prepareKnowledgeBase(); prepareStatefulKnowledgeSession(); prepareAccounts(); } private static void prepareAccounts() { account123 = new Account(); account123.setNumber(accountNumber123); account456 = new Account(); account456.setNumber(accountNumber456); } private static void prepareStatefulKnowledgeSession() { KnowledgeSessionConfiguration sessConfig = KnowledgeBaseFactory.newKnowledgeSessionConfiguration(); sessConfig.setOption(ClockTypeOption.get("pseudo")); session = knowledgeBase.newStatefulKnowledgeSession(sessConfig, null); } private static void prepareKnowledgeBase() { try { KnowledgeBuilder builder = KnowledgeBuilderFactory.newKnowledgeBuilder(); builder.add(ResourceFactory.newClassPathResource(DRL_FILENAME), ResourceType.DRL); KnowledgeBuilderErrors errors = builder.getErrors(); if (errors.size() > 0) { for (KnowledgeBuilderError error : errors) { System.err.println(error); } throw new IllegalArgumentException("Could not parse knowledge."); } knowledgeBase = KnowledgeBaseFactory.newKnowledgeBase(); knowledgeBase.addKnowledgePackages(builder.getKnowledgePackages()); } catch (Exception e) { e.printStackTrace(); } } public static void main(String[] args) { setUp(); try { SessionPseudoClock clock = session.getSessionClock(); WorkingMemoryEntryPoint eventStream = session.getWorkingMemoryEntryPoint(ENTRY_POINT); eventStream.insert(new Event(accountNumber123, 50.00)); eventStream.insert(new Event(accountNumber456, 500.00)); clock.advanceTime(5, TimeUnit.DAYS); eventStream.insert(new Event(accountNumber123, 40.00)); eventStream.insert(new Event(accountNumber456, 400.00)); clock.advanceTime(10, TimeUnit.DAYS); eventStream.insert(new Event(accountNumber123, 30.00)); eventStream.insert(new Event(accountNumber456, 300.00)); clock.advanceTime(15, TimeUnit.DAYS); eventStream.insert(new Event(accountNumber123, 20.00)); eventStream.insert(new Event(accountNumber456, 200.00)); clock.advanceTime(20, TimeUnit.DAYS); eventStream.insert(new Event(accountNumber123, 10.00)); eventStream.insert(new Event(accountNumber456, 100.00)); session.insert(account123); session.fireAllRules(); } catch (Throwable t) { t.printStackTrace(); } } } -- View this message in context: http://drools.46999.n3.nabble.com/window-length-with-variables-as-constra... 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