Hi,
To keep it simple I would say that a tuple is a kind of key-value pair. In
storm the list of keys(or names) is defined in the declareOutputFields().
In word count topology the names can be ("word","count").
Every value which is emitted from the spout or bolt is associated with the
name declared in the declareOutputFields(). So if a tuple emitted in the
above example is ("sample",1), then sample is the word and 1 is the count.
In this example you will notice that the values emitted are of types String
and Integer. You need not specify the type of the value which is emitted
from the spout or bolt.
Regards,
Richards Peter.
