Package com.linecorp.armeria.client.grpc

Class GrpcWebUtil

java.lang.Object

com.linecorp.armeria.client.grpc.GrpcWebUtil

@UnstableApi
public final class GrpcWebUtil
extends Object

Utilities for working with gRPC-Web.

Note that this class will be removed once a retry ClientInterceptor is added. See: https://github.com/line/armeria/issues/2860

Method Summary

Modifier and Type	Method	Description
static HttpHeaders	parseTrailers(ClientRequestContext ctx, HttpData response)	Returns a gRPC-Web trailers parsed from the specified response body.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

parseTrailers

@Nullable public static HttpHeaders parseTrailers(ClientRequestContext ctx, HttpData response)

Returns a gRPC-Web trailers parsed from the specified response body. null if fail to parse a gRPC-Web trailers.

A gRPC-Web response does not contain a separated trailers according to the gRPC-Web spec:

• Trailers must be the last message of the response.
• Trailers may be sent together with response headers, with no message in the body.

That means the response trailers should be pulled out from AggregatedHttpResponse.headers()} or parsed from AggregatedHttpMessage.content().

This method is useful when RetryRuleWithContent needs GrpcHeaderNames.GRPC_STATUS to decide whether to retry. For example:

 Clients.builder(grpcServerUri)
        .decorator(RetryingClient.newDecorator(
                RetryRuleWithContent.onResponse((ctx, response) -> {
                    return response.aggregate().thenApply(aggregated -> {
                        HttpHeaders trailers = GrpcWebUtil.parseTrailers(ctx, aggregated.content());
                        // Retry if the 'grpc-status' is not equal to 0.
                        return trailers != null && trailers.getInt(GrpcHeaderNames.GRPC_STATUS) != 0;
                    });
                })))
        .build(MyGrpcStub.class);
 

Throws:

RequestLogAvailabilityException - if the RequestLogProperty.SCHEME or RequestLogProperty.RESPONSE_HEADERS is not available yet from the RequestLog of the specified RequestContext.log().