extract abstract method

SpanContext? extract(String format, dynamic carrier)

Returns a SpanContext instance extracted from carrier in the given format.

• Throws SpanContextCorruptedError if the SpanContext is missing fields or contains invalid values.

OpenTracing defines a common set of format values (see formatTextMap, formatHttpHeaders, and formatBinary), and each has an expected carrier type.

Consider this pseudo-code example:

// Use the inbound HTTP request's headers as a text map carrier.
var headersCarrier = inboundHttpReq.headers;
var wireCtx = Tracer.extract(Constants.formatHttpHeaders, headersCarrier);
var serverSpan = Tracer.startSpan('...', { childOf : wireCtx });

Implementation

SpanContext? extract(String format, dynamic carrier);