Question

I'm currently doing a Flink project. The main idea of the project is to read a datastream of JSON's (network logs), correlate them, and generate a new JSON, which is a combination of different JSON's information.

At this moment, I'm able to read the JSON's, genereate a KeyedStream (based on the machine that generates the log), and then generate a window stream of 5 seconds.

The next step I want to perform is to use the apply function to the window and combine the information of each JSON. I'm a bit confused of how to do it.

The code I currently have is the following one:

$newarr = array(
'id' => 'Id',
'payment_status' => 'Payment status',
'created_at' => 'Created At');

$columns = $newarr;

The .apply(new generateMetaAlert()) part is complaining with the next error:

The method apply(WindowFunction,R,Tuple,TimeWindow>) in the type WindowedStream,Tuple,TimeWindow> is not applicable for the arguments (MetaAlertGenerator.generateMetaAlert)

Any other code structure proposal distinct that the one I made up?

Thank you in advance for your help

Answer 1

当您应用/usr/local/lib/node_modules函数（不使用匿名类）时，自定义keyBy（第3个字段）中的键的类型应为WindowFunction，因为编译器无法确定你的钥匙的类型。此代码编译时没有错误（考虑到我试图用虚拟代码填充空白）：

Tuple

但最简单的方法是使用匿名类，以便保持public class Test { public Test() { StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment(); env.setStreamTimeCharacteristic(TimeCharacteristic.EventTime); DataStream<String> events = env.readTextFile("datastream.log"); DataStream<Tuple2<String, JSONObject>> MetaAlert = events .flatMap(new JSONParser()) .keyBy(0) .timeWindow(Time.seconds(5)) .apply(new GenerateMetaAlert()); } public class JSONObject { } public class JSONParser implements FlatMapFunction<String, Tuple2<String, JSONObject>> { @Override public void flatMap(String s, Collector<Tuple2<String, JSONObject>> collector) throws Exception { } } public class GenerateMetaAlert implements WindowFunction<Tuple2<String, JSONObject>, Tuple2<String, JSONObject>, Tuple, TimeWindow> { @Override public void apply(Tuple key, TimeWindow timeWindow, Iterable<Tuple2<String, JSONObject>> iterable, Collector<Tuple2<String, JSONObject>> collector) throws Exception { } } }类型：

String

最后，如果你想保留这个课程，但你也希望保持你的关键类型，你可以实现DataStream<Tuple2<String, JSONObject>> MetaAlert = events .flatMap(new JSONParser()) .keyBy(0) .timeWindow(Time.seconds(5)) .apply(new WindowFunction<Tuple2<String, JSONObject>, Tuple2<String, JSONObject>, Tuple, TimeWindow>() { @Override public void apply(Tuple tuple, TimeWindow timeWindow, Iterable<Tuple2<String, JSONObject>> iterable, Collector<Tuple2<String, JSONObject>> collector) throws Exception { // Your code here } });：

KeySelector

Flink apply function on timeWindow

1 个答案: