The tracing ecosystem today is fairly fragmented and probably confusing. Traditional APM vendors made a lot of investment in the agent-based instrumentation, all with their own APIs and data protocols. After Twitter released Zipkin, the first industrial-grade open source tracing system, it started gaining traction among the users as the de facto standard, at least for its B3 metadata propagation format (many systems at Twitter were named after birds, and Zipkin was originally called Big Brother Bird, or B3, which was used as the prefix for HTTP headers, for example, X-B3-TraceId).
In 2016, both Google and Amazon announced the availability of their own managed tracing systems, Stackdriver and X-Ray, both with their own metadata and trace data formats. These systems can be used to trace the applications running in the respective clouds, as well as receive tracing data from the internal applications running, by their customers on premises. A number of other tracing systems...