This is a helper for messaging (queue or topic) libraries such as JMS and
Kafka. Specifically, this includes samplers for producers and consumers,
configured with MessagingTracing.
The MessagingTracing class holds a reference to a tracing component and
sampling policy.
The default sampling policy is to use the default (trace ID) sampler for consumer and producer requests.
For example, if there's a incoming message that has no trace IDs in its
headers, the sampler indicated by MessagingTracing.Builder.consumerSampler
decides whether or not to start a new trace. Once a trace is in progress, it is
used for any outgoing messages (producer requests).
On the other hand, you may have outgoing messages didn't originate from a
server or message consumer. For example, bootstrapping your application might
send a message to an infrastructure service. In this case, the policy defined
by MessagingTracing.Builder.producerSampler decides if a new trace will be
started or not.
You can change the sampling policy by specifying it in the MessagingTracing
component. The default implementation MessagingRuleSampler allows you to
declare rules based on declare rules based on messaging properties and apply an
appropriate sampling rate.
Ex. Here's a sampler that traces 100 consumer requests per second, except for
the "alerts" channel. Other requests will use a global rate provided by the
Tracing component.
import brave.sampler.Matchers;
import static brave.messaging.MessagingRequestMatchers.channelNameEquals;
messagingTracingBuilder.consumerSampler(MessagingRuleSampler.newBuilder()
.putRule(channelNameEquals("alerts"), Sampler.NEVER_SAMPLE)
.putRule(Matchers.alwaysMatch(), RateLimitingSampler.create(100))
.build());Check for instrumentation written here and Zipkin's list before rolling your own Messaging instrumentation! Besides documentation here, you should look at the core library documentation as it covers topics including propagation. You may find our feature tests helpful, too.