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Posted to issues@flink.apache.org by "zhangtianyu (Jira)" <ji...@apache.org> on 2022/04/29 11:13:00 UTC
[jira] [Commented] (FLINK-27456) mistake and confusion with CEP example in docs
[ https://issues.apache.org/jira/browse/FLINK-27456?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17529911#comment-17529911 ]
zhangtianyu commented on FLINK-27456:
-------------------------------------
t-1退订【18120144173@189.cn】
jira <ji...@apache.org>写到：
David Anderson created FLINK-27456:-------------------------------------- Summary: mistake and confusion with CEP example in docs Key: FLINK-27456 URL: https://issues.apache.org/jira/browse/FLINK-27456 Project: Flink Issue Type: Bug Components: Documentation, Library / CEP Affects Versions: 1.14.4 Reporter: David Anderson[https://nightlies.apache.org/flink/flink-docs-master/docs/libs/cep/#contiguity-within-looping-patterns]In the section of the docs on contiguity within looping patterns, what it says about strict contiguity for the given example is either incorrect or very confusing (or both). It doesn't help that the example code doesn't precisely match the scenario described in the text.To study this, I implemented the example in the text and find it produces no output for strict contiguity (as I expected), which contradicts what the text says.{code:java}public class StreamingJob { public static void main(String[] args) throws Exception { StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment(); DataStream events = env.fromElements("a", "b1", "d1", "b2", "d2", "b3", "c"); AfterMatchSkipStrategy skipStrategy = AfterMatchSkipStrategy.skipPastLastEvent(); Pattern pattern = Pattern. begin("a", skipStrategy) .where( new SimpleCondition () { @Override public boolean filter(String element) throws Exception { return element.startsWith("a"); } }) .next("b ") .where( new SimpleCondition () { @Override public boolean filter(String element) throws Exception { return element.startsWith("b"); } }) .oneOrMore().consecutive() .next("c") .where( new SimpleCondition () { @Override public boolean filter(String element) throws Exception { return element.startsWith("c"); } }); PatternStream patternStream = CEP.pattern(events, pattern).inProcessingTime(); patternStream.select(new SelectSegment()).addSink(new PrintSinkFunction<>(true)); env.execute(); } public static class SelectSegment implements PatternSelectFunction { public String select(Map
> mistake and confusion with CEP example in docs
> ----------------------------------------------
>
> Key: FLINK-27456
> URL: https://issues.apache.org/jira/browse/FLINK-27456
> Project: Flink
> Issue Type: Bug
> Components: Documentation, Library / CEP
> Affects Versions: 1.14.4
> Reporter: David Anderson
> Priority: Major
>
> [https://nightlies.apache.org/flink/flink-docs-master/docs/libs/cep/#contiguity-within-looping-patterns]
> In the section of the docs on contiguity within looping patterns, what it says about strict contiguity for the given example is either incorrect or very confusing (or both). It doesn't help that the example code doesn't precisely match the scenario described in the text.
> To study this, I implemented the example in the text and find it produces no output for strict contiguity (as I expected), which contradicts what the text says.
> {code:java}
> public class StreamingJob {
> public static void main(String[] args) throws Exception {
> StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
> DataStream<String> events = env.fromElements("a", "b1", "d1", "b2", "d2", "b3", "c");
> AfterMatchSkipStrategy skipStrategy = AfterMatchSkipStrategy.skipPastLastEvent();
> Pattern<String, String> pattern =
> Pattern.<String>begin("a", skipStrategy)
> .where(
> new SimpleCondition<String>() {
> @Override
> public boolean filter(String element) throws Exception {
> return element.startsWith("a");
> }
> })
> .next("b+")
> .where(
> new SimpleCondition<String>() {
> @Override
> public boolean filter(String element) throws Exception {
> return element.startsWith("b");
> }
> })
> .oneOrMore().consecutive()
> .next("c")
> .where(
> new SimpleCondition<String>() {
> @Override
> public boolean filter(String element) throws Exception {
> return element.startsWith("c");
> }
> });
> PatternStream<String> patternStream = CEP.pattern(events, pattern).inProcessingTime();
> patternStream.select(new SelectSegment()).addSink(new PrintSinkFunction<>(true));
> env.execute();
> }
> public static class SelectSegment implements PatternSelectFunction<String, String> {
> public String select(Map<String, List<String>> pattern) {
> return String.join("", pattern.get("a"))
> + String.join("", pattern.get("b+"))
> + String.join("", pattern.get("c"));
> }
> }
> }
> {code}
>
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