[APM] Dependencies Downstream services

[glucaci]

• When using messaging the traces are splitted between the sender service and the receiver service. In the bellow example the gateway api is calling todo api which is sending a message and the user api is receiving it.

• In this case is there only one way navigation possible, from the receiver to the sender. This is possible by navigating to the Receive /users trace and click on View full trace which I think is linked to the sender by the trace.id

• The sender has also a link to a Dependency/Backend

• The dependency is displaying only Upstream services. Would it be possible to display also the Downstream services? It will be very useful to see all the consumers from a specific message.

[elasticmachine]

Pinging @elastic/apm-ui (Team:apm)

[sorenlouv]

@chrisdistasio This came up, and is yet another use case for https://github.com/elastic/kibana/issues/146531. If we had filter capabilities on service map we could link from dependencies to service map filtered by the selected span.name. Thus the service map would only show upstream and downstream services from from that particular operation.