Mastering Apache Storm

Trident function

Trident functions contain logic to modify the original tuple. A Trident function gets a set of fields of the tuple as input and emits one or more tuples as output. The fields of the output tuples are merged with the fields of the input tuple to form the complete tuple, which will pass to the next action in the topology. If the Trident function emits no tuples corresponding to the input tuple, then that tuple is removed from the stream.

We can write a custom Trident function by extending the storm.trident.operation.BaseFunction class and implementing the execute(TridentTuple tuple, TridentCollector collector) method.

Let's write the sample Trident function, which will return the new field called sum:

public class SumFunction ...