There are several good reasons to want to have more than one output stream from your Flink pipeline, such as reporting:
exceptions
malformed events
late events
operational alerts, such as timed-out connections to external services
Side outputs are a convenient way to do this.
Each side output channel is associated with an OutputTag. The tags have generic types that correspond to the type of the side output’s DataStream, and they have names. Two OutputTags with the same name should have the same type, and will refer to the same side output.
There are several good reasons to want to have more than one output stream from your Flink pipeline, such as reporting:
exceptions malformed events late events operational alerts, such as timed-out connections to external services Side outputs are a convenient way to do this.
Each side output channel is associated with an OutputTag. The tags have generic types that correspond to the type of the side output’s DataStream, and they have names. Two OutputTags with the same name should have the same type, and will refer to the same side output.