Storm Blueprints: Patterns for Distributed Real-time Computation

Introducing Trident topologies

To fulfill these requirements, we will need to count the occurrences in our topologies. This can be challenging while using standard Storm topologies because tuples can get replayed, which leads to double counting. As we will see in the next few sections, Trident provides primitives to solve this problem.

We will use the following topology:

The code for the preceding topology is as follows:

public class OutbreakDetectionTopology { public static StormTopology buildTopology() { TridentTopology topology = new TridentTopology(); DiagnosisEventSpout spout = new DiagnosisEventSpout(); Stream inputStream = topology.newStream("event", ...