Support streaming services for JSON transcoding

[jrhee17]

Currently, Armeria's HttpJsonTranscodingService doesn't support streaming messages and throws an exception.

armeria/grpc/src/main/java/com/linecorp/armeria/server/grpc/HttpJsonTranscodingService.java

Lines 162 to 165 in 104855a

	checkArgument(methodDefinition.getMethodDescriptor().getType() == MethodType.UNARY,
	"Only unary methods can be configured with an HTTP/JSON endpoint: " +
	"method=%s, httpRule=%s",
	methodDefinition.getMethodDescriptor().getFullMethodName(), httpRule);

Recently, we saw an issue where some users with streaming services in their proto files weren't able to use transcoding at all since the above exception was thrown. #5828 #5829

Although a workaround was added to log a warning instead of throwing an exception, this also probably isn't ideal since users will still see warning logs for which they can't (and shouldn't) take action.

Moreover, it seems like grpc-gateway supports streaming as seen in the following issue where ndjson is used: grpc-ecosystem/grpc-gateway#581

In an effort to 1) remove this discrepancy with upstream and 2) remove unnecessary warning logs, I suggest that we also support streaming messages for HttpJsonTranscodingService.

[jrhee17]

Note: At least to follow-up on #5829, we may want to consider returning a 405 Method Not Allowed when a request to a streaming service is made until this issue is fully addressed.

[dipeshsingh253]

Hi @jrhee17 , I would like to contribute to this issue. Can you please assign it to me.?

[jrhee17]

Sure, assigned

[dipeshsingh253]

Hi @jrhee17 ,

I followed the docs and tried to build Armeria locally using ./gradlew --parallel build but faced some failed test cases.

[dipeshsingh253]

Hi @jrhee17, @ikhoon , I have successfully set up the dev environment in locally.

I went through the HttpJsonTranscodingService.java file. Currently, we are just logging in case of nonunary.

Currently, two things I can see are mentioned, but I am not sure how to approach them yet. Can you please explain in brief or redirected me to some resource which might help me.

In an effort to 1) remove this discrepancy with upstream and 2) remove unnecessary warning logs, I suggest that we also support streaming messages for HttpJsonTranscodingService.