Span Data Conventions

The Span Interface specifies a series of timed application events that have a start and end time. Below describes the conventions for the Span interface for the data field on the span.

The data field on the span is expected to follow OpenTelemetry's semantic conventions for attributes as much as possible.

Keys on the data field should be lower-case and use underscores instead of camel-case. There are some exceptions to this, but these exist because of backwards compatability.

Below describes the conventions for the Span interface for the data field on the span that are currently used by the product or are important to bring up.


http.querystringThe Query string present in the URL.?foo=bar&bar=baz
http.fragmentstringThe Fragments present in the URL.#foo=bar


blocked_main_threadbooleanWhether the main thread was blocked by the span.true
call_stackStackFrame[]The most relevant stack frames, that lead to the File I/O span. The stack frame should adhere to the StackFrame interface.


urlstringThe URL of the resource that was fetched.
methodstringThe HTTP method used.GET
typestringThe type of the resource that was fetched.xhr
Encoded Body SizenumberThe encoded body size of the request.123
Decoded Body SizenumberThe decoded body size of the request.456
Transfer SizenumberThe transfer size of the request.789
resource.render_blocking_statusstringThe render blocking status of the resource.non-blocking
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