Mastering Distributed Tracing

The Span Count job

Let's look at how the SpanCountJob is implemented. The Jaeger collector writes spans to Kafka in Protobuf format, so we need a way to parse them. The package io.jaegertracing.api_v2 is auto-generated by the Protobuf compiler from the IDL file found in the Jaeger codebase (model/proto/model.proto in Jaeger v1.8). Protobuf-generated classes are not particularly convenient to work with in Flink, so in the model package we define a simplified model of the trace that only contains the span data that we need for the purpose of the span count calculations:

public class Span implements Serializable { public String traceId; public String spanId; public String serviceName; public String operationName; public long startTimeMicros; public ...