Here is the main logic for jaeger agent and jaeger collector. (Based on jaeger 1.13.1)
Jaeger Agent
Collect UDP packet from 6831 port, convert it to model.Span, send to collector by gRPC
Jaeger Collector
Process gRPC or process packet from Zipkin(port 9411).
Jaeger Query
Listen gRPC and HTTP request from 16686.