tags: implement spec for HTTP propagation (original) (raw)

While working on the interop tests across Go and Java, one of the requirements was that tag propagation be tested for both gRPC and HTTP. In Go, we only have tag propagation for gRPC which
sends tags as an encoded blob in the metadata headers(I don't see a spec here though, so perhaps also file an issue for it?).

This issue is a request for us to work the spec for it and I left reminders for that such as
https://github.com/census-instrumentation/opencensus-experiments/blob/c6a2b2d00eb184da894de2ae14ef5dce4ab45951/integration/go-http-client/client_test.go#L122
and I also filed an issue on the Go package census-instrumentation/opencensus-go#537