Storm Blueprints: Patterns for Distributed Real-time Computation

Introducing the word count topology data flow

Our word count topology (depicted in the following diagram) will consist of a single spout connected to three downstream bolts.

Word count topology

Sentence spout

The SentenceSpout class will simply emit a stream of single-value tuples with the key name "sentence" and a string value (a sentence), as shown in the following code:

{ "sentence":"my dog has fleas" }

To keep things simple, the source of our data will be a static list of sentences that we loop over, emitting a tuple for every sentence. In a real-world application, a spout would typically connect to a dynamic source, such as tweets retrieved from ...