我想用FlinkCEP只在模式上做一個'懶惰'匹配。我怎樣才能做到這一點? 例如我有一個輸入流ACABCABCB,我想匹配A後面的C得到只有3場比賽,而不是6場比賽。Ho我可以和Flink CEP做一個懶惰的匹配嗎
我創建了以下示例來說明我的問題。
val env = StreamExecutionEnvironment.createLocalEnvironment(1)
env.setStreamTimeCharacteristic(TimeCharacteristic.ProcessingTime)
case class MyEvent(id: Int, kind: String, value: String)
case class MyAggregatedEvent(id: Int, concatenatedValue: String)
val eventStream = env.fromElements(
MyEvent(1, "A", "1"), MyEvent(1, "C", "1"),
MyEvent(1, "A", "2"), MyEvent(1, "B", "1"), MyEvent(1, "C", "2"),
MyEvent(1, "A", "3"), MyEvent(1, "D", "2"), MyEvent(1, "C", "3"),
MyEvent(1, "B", "3")
)
val pattern: Pattern[MyEvent, _] = Pattern
.begin[MyEvent]("pA").where(e => e.kind == "A")
.next("pC").where(e => e.kind == "C")
.within(Time.seconds(5))
val patternNextStream: PatternStream[MyEvent] = CEP.pattern(eventStream.keyBy(_.id), pattern)
val outNextStream: DataStream[MyAggregatedEvent] = patternNextStream.flatSelect {
(pattern: scala.collection.mutable.Map[String, MyEvent], collector: Collector[MyAggregatedEvent]) =>
val partA = pattern.get("pA").get
val partC = pattern.get("pC").get
collector.collect(MyAggregatedEvent(partA.id, partA.value + "=>" + partC.value))
}
outNextStream.print()
env.execute("Experiment")
這使我下面的輸出:
MyAggregatedEvent(1,1 => 1)
當我模式更改爲:
val pattern: Pattern[MyEvent, _] = Pattern
.begin[MyEvent]("pA").where(e => e.kind == "A")
.followedBy("pC").where(e => e.kind == "C")
.within(Time.seconds(5))
然後印刷如下:
MyAggregatedEvent(1,1 => 1)
MyAggregatedEvent(1,1 => 2)
MyAggregatedEvent(1,2 => 2)
MyAggregatedEvent(1,1 => 3)
MyAggregatedEvent(1,2 = > 3)
MyAggregatedEvent(1,3 => 3)
如何創建的圖案,只有每個事件一次匹配,從而使我的輸出將是:
MyAggregatedEvent(1,1 => 1)
MyAggregatedEvent(1,2 => 2)
MyAggregatedEvent(1,3 => 3)