如何在drools-fusion中编写动态时态规则

Question

我正在尝试为一个事件编写一条规则，该规则需要检查在其他事件发生后的某个时间窗口内是否发生了某些事情。目前，代码看起来像这样(它可以正常工作)：

    rule "Detect BPM reseed not starting when requested from Mart"
        when
            $martDailyRefreshRequestedEvent: MessageSentEvent(
                $correlationId: correlationId,
                $when: timestamp,
                messageTypeName == "MartDailyRefreshCompletedEvent")
                    from entry-point "mart"
            not ( MessageHandleStartedEvent(
                    this after[0ms, 30s] $martDailyRefreshRequestedEvent, 
                    correlationId == $correlationId,
                    messageTypeName == "MartDailyRefreshCompletedEvent") 
                            from entry-point "bpm")
        then
            notifier.notify("BPM not responding to MartDailyRefreshCompletedEvent quick enough", 
                String.format(
                    "At **%s** Mart sent out a **MartDailyRefreshCompletedEvent**.\n\n**BPM** was supposed to react to it within **30 seconds**.",
                    $when));
    end

目前，30s实际上是硬编码的。我读到，如果你想参数化规则，你需要使用在知识库中断言的其他事实，但我不知道如何为时态规则做到这一点。

那么:如何在此规则中“配置”30s，以便可以在应用程序外部更改该值？如下所示：MessageHandleStartedEvent(this after [ $duration ] ...

Answer 1

您可以使用模板从外部Drools提供硬编码的30。

template dynamicTimer
rule "Detect BPM reseed not starting when requested from Mart"
    when
        $martDailyRefreshRequestedEvent: MessageSentEvent(
            $correlationId: correlationId,
            $when: timestamp,
            messageTypeName == "MartDailyRefreshCompletedEvent")
                from entry-point "mart"
        not ( MessageHandleStartedEvent(
                this after[0ms, @{timeout}s] $martDailyRefreshRequestedEvent, 
                correlationId == $correlationId,
                messageTypeName == "MartDailyRefreshCompletedEvent") 
                        from entry-point "bpm")
    then
        notifier.notify("BPM not responding to MartDailyRefreshCompletedEvent quick enough", 
            String.format(
                "At **%s** Mart sent out a **MartDailyRefreshCompletedEvent**.\n\n**BPM** was supposed to react to it within **@{timeout} seconds**.",
                $when));
end
end template

然后，您只需要提供30作为模板参数：

ObjectDataCompiler converter = new ObjectDataCompiler();
InputStream templateStream = getClass().getResourceAsStream(resource.getFilePath());
Collection<Map<String, String>> paramMaps = new ArrayList<>();
Map<String,String> param = new HashMap<>();
param.put("timeout", "30");
paramMaps.add(param);
String drl = converter.compile(paramMaps, templateStream);
Reader rdr = new StringReader(drl);
kbuilder.add(ResourceFactory.newReaderResource(rdr), ResourceType.DRL);