Support streaming HttpBody proto?

[npuichigo]

The support for handling google.api.HttpBody is cool, especially when I want to directly reply http response with audio content_type. I notice that streaming case is remained to be done, so may I ask you when will that be supported? It's really use for me in implementing speech synthesis because l can transfer large audio data to client by clipping them into audio clips with chunked audio/mp3 content_type.

[mattklein123]

@lizan

[lizan]

@npuichigo we don't have specific timeline to implement that. That is useful so if you're interested feel free to open a PR and I can help you with that.

[npuichigo]

@dio

[npuichigo]

I tried to add the logic of httpbody streaming in grpc-gateway repo, and maybe I can try to implement that in envoy. (https://github.com/grpc-ecosystem/grpc-gateway/pull/1088/files) Can you give me some advice?

[belyalov]

Is this issue about this to-be-done part?

envoy/source/extensions/filters/http/grpc_json_transcoder/json_transcoder_filter.cc

Lines 521 to 525 in 404d73c

	// TODO(dio): Add support for streaming case.
	if (has_http_body_response_) {
	buildResponseFromHttpBodyOutput(*response_headers_, data);
	return Http::FilterDataStatus::StopIterationAndBuffer;
	}

[belyalov]

@lizan - ping,
if this is correct - please assign this to me - I'll be working on it.

[qiwzhang]

Yes, I think it is referring to support server streaming of HttpBody.

But HttpBody has content-type, will we allow different content-type from different HttpBody? I don't think different chunk can have different content-type.

[belyalov]

Yep, I think it is suppose to be either:

• the same for all gRPC stream response messages
• first message has content-type set, the rest is unset

As for workaround for "misbehaves" upstream - seems we can just ignore content-type for messages except first?

[lizan]

@belyalov yes the part of code you're referring is right.

As for workaround for "misbehaves" upstream - seems we can just ignore content-type for messages except first?

I think this is fine, as long as we clearly document it.

[npuichigo]

@belyalov Many thanks if you can help to fix this.😀

[npuichigo]

@lizan by the way, is this kind of transcoder can be directly used in ambassador or istio?