Terminology - Hypertrace

Hypertrace supports OpenTracing which is being followed by most distributed tracing platforms. It gives Hypertrace ability to fetch traces from all available collectors and work as a single aggregator.

Let's start with undertsanding some basic terms around distributed tracing as per the specifications defined by OpenTracing.

Spans

The “span” is the primary building block or a logical unit of a distributed trace, representing an individual unit of work done in a distributed system.

Each component of the distributed system contributes a span - a named, timed operation representing a piece of the workflow. Multiple spans assemble to become a trace. Each span has it's own operation name along with a start and finish timestamp, A set key:value span Tags, A set key:value span logs and A SpanContext.

Logs

Logs are key:value pairs that are useful for capturing span-specific logging messages and other debugging or informational output from the application itself.

SpanContext

Each SpanContext encapsulates the following state:

Any OpenTracing-implementation-dependent state (for example, trace and span ids) needed to refer to a distinct Span across a process boundary
Baggage Items, which are just key:value pairs that cross process boundaries

Traces

Traces in OpenTracing are defined implicitly by their Spans. In particular, a Trace can be thought of as a directed acyclic graph (DAG) of Spans, where the edges between Spans are called References.

For example, the following is an example Trace made up of 8 Spans:

Causal relationships between Spans in a single Trace


        [Span A]  ←←←(the root span)
            |
     +------+------+
     |             |
 [Span B]      [Span C] ←←←(Span C is a `ChildOf` Span A)
     |             |
 [Span D]      +---+-------+
               |           |
           [Span E]    [Span F] >>> [Span G] >>> [Span H]
                                       ↑
                                       ↑
                                       ↑
                         (Span G `FollowsFrom` Span F)

Sometimes it's easier to visualize Traces with a time axis as in the diagram below:

Temporal relationships between Spans in a single Trace


––|–––––––|–––––––|–––––––|–––––––|–––––––|–––––––|–––––––|–> time

 [Span A···················································]
   [Span B··············································]
      [Span D··········································]
    [Span C········································]
         [Span E·······]        [Span F··] [Span G··] [Span H··]

Collector

Collector receives traces from various agents in our case Hypertrace can collect traces from Jaeger, Zipkin, OpenCensus and OpenTelemetry agents.