Support for Proxying SOAP/XML Endpoints via Spring Cloud Gateway

Question

Trying to log request and response while proxying soap service using Spring cloud gateway. Below is the code snippet... which is throwing IllegalStateException.

java.lang.IllegalStateException: Only one connection receive subscriber allowed. at reactor.netty.channel.FluxReceive.startReceiver(FluxReceive.java:271) [reactor-netty-0.8.4.RELEASE.jar:0.8.4.RELEASE] at reactor.netty.channel.FluxReceive.subscribe(FluxReceive.java:121) [reactor-netty-0.8.4.RELEASE.jar:0.8.4.RELEASE]

--- Spring Versions ---

SpringBoot                  : 2.1.2.RELEASE
spring-cloud-gateway        : 2.1.1.BUILD-SNAPSHOT
spring-boot-starter-webflux : 2.1.2.RELEASE
reactor-core                : 3.2.5.RELEASE

GatewaySampleApplication

public class  GatewaySampleApplication {
@Bean
public RouteLocator customRouteLocator(RouteLocatorBuilder builder) {
return builder.routes() 
.route(
r ->
r.path("/security/getToken")
.filters( f -> f.preserveHostHeader()
.filter(new PolicyHandlerReactive()))
.uri("http://targetendpoint.xyz.com")
)
.build();
}
}

PolicyHandlerReactive :

PolicyHandlerReactive implements GatewayFilter  {

@Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) 
    {
        ServerHttpRequest request = (ServerHttpRequest) exchange.getRequest();
                Flux<DataBuffer> xmlReqFlux = request.getBody();    
                Mono<List<DataBuffer>> monoDataList = xmlReqFlux.collectList();
                monoDataList.map(dataA -> logRequest2(dataA)).subscribe();
        return chain.filter(exchange);
        }
}

private List<DataBuffer> logRequest(List<DataBuffer> dataA) {           

    ListIterator<DataBuffer> dataAList = dataA.listIterator();

    while(dataAList.hasNext() ) {
        DataBuffer dataBuffer = dataAList.next();
        InputStream is = dataBuffer.asInputStream();
        System.out.println(convertStreamToString(is));
    }       
    return dataA;
}   

Answer 1

able to sort this out using .modifyRequestBody instead of filters... updated java DSL below...

    .route(
                    r ->
                    r.path("external/v2/security/")
                    .filters( f -> f
                            .preserveHostHeader()
                            .modifyRequestBody(String.class, String.class, 
                            (exchange, s) -> {
                                Mono<String> dataA = Mono.just(s); 
                                dataA.subscribe(System.out::print); 
                                return dataA; 
                            })                              
                         )                                                                                               
                    .uri("http://targetendpoint.xyz.com")
                    )