Hi, After implementing SourceFunction, you can use it to create a DataStream using env.addSource() in your main method. For example, if you have your custom source class with the name CustomSource that implements SourceFunction<String>, then it can be used for getting input data and the if-statement after it can be removed:
// get input data DataStream<String> text = env.addSource(new CustomSource()); ExampleCountSource in [1] implements SourceFunction<Long>, which can be used to get a DataStream with type Long, not String, such as: DataStream<Long> numbers = env.addSource(new ExampleCountSource()); If you only want to have a look at how checkpoint being triggered, see [2] for another sample that has a custom endless source named TransactionSource. When enabled checkpoint it can be triggered with your rules. It might be easier for a beginner than implement it by yourself. However, it may not restore from a checkpoint perfectly since it doesn't implement CheckpointedFunction. That is to say, if you want your source to be restored successfully after failures, CheckpointedFunction is also necessary and ExampleCountSource in [1] is a good example. [1]. https://ci.apache.org/projects/flink/flink-docs-release-1.12/api/java/org/apache/flink/streaming/api/functions/source/SourceFunction.html [2]. https://ci.apache.org/projects/flink/flink-docs-release-1.12/try-flink/datastream_api.html Regards, Smile -- Sent from: http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/
