Package com.linecorp.armeria.common.grpc.protocol

Class GrpcWebTrailers

java.lang.Object
com.linecorp.armeria.common.grpc.protocol.GrpcWebTrailers
@UnstableApi public final class GrpcWebTrailers extends Object
Retrieves gRPC-Web trailers.

  • Method Details

    • get

      @Nullable public static @Nullable HttpHeaders get​(RequestContext ctx)
      Returns the gRPC-Web trailers which was set to the specified RequestContext using set(RequestContext, HttpHeaders).

      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 AggregatedHttpObject.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) -> {
                    // Note that we should aggregate the response to get the trailers.
                    return response.aggregate().thenApply(aggregated -> {
                        HttpHeaders trailers = GrpcWebTrailers.get(ctx);
                        // Retry if the 'grpc-status' is not equal to 0.
                        return trailers != null && trailers.getInt(GrpcHeaderNames.GRPC_STATUS) != 0;
                    });
                })))
        .build(MyGrpcStub.class);

    • set

      public static void set​(RequestContext ctx, HttpHeaders trailers)
      Sets the specified gRPC-Web trailers to the RequestContext.