THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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Clearer definition: From the DataStream's perspective, it only needs to understand the semantics of functions. Built-in operations such as map / flatMap / reduce / join can still be supported, but are decoupled from the core framework. That is to say, for DataStream V2, every operation is a process function .
Don'
t expose operators to users: We believe functions with access to proper runtime information and services are good enough for users to define custom data processing logics. Operators on the other hand are more an internal concept of Flink and users should not be allowed to directly use them. Besides, in V1 users are invited to extend `AbstractStreamOperator` in order to define their custom operators, leading to unnecessary dependencies and unpredictable behaviors. In V2, users should define their custom behaviors by implementing interfaces rather than extending framework classes.t expose operators to users: We believe functions with access to proper runtime information and services are good enough for users to define custom data processing logics. Operators on the other hand are more an internal concept of Flink and users should not be allowed to directly use them. Besides, in V1 users are invited to extend `AbstractStreamOperator` in order to define their custom operators, leading to unnecessary dependencies and unpredictable behaviors. In V2, users should define their custom behaviors by implementing interfaces rather than extending framework classes.
Requirements for input and output streams
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