can skywalking OAP receive opentelemetry trace now

[Aresxiao]

I have a question when using opentelemetry and skywalking. In java project, use opentelemetry to generate trace and span infomation, then I want to collect these trace to skywalking aop to analysis and display. I have deploy skywalking version is 10.2.0, and there is the java code:

public class Main {

    private static final int MAX_PACKET_LEN = 65536;
    private static Tracer tracer;

    public static void main(String[] args) {
        Config.readConfig(args);
        initOpenTelemetry();

        Pointer handle = WinDivert.INSTANCE.WinDivertOpen(Config.filter, WinDivert.WINDIVERT_LAYER_NETWORK, (short)0, 0L);
        if (handle == null) {
            System.err.println("WinDivertOpen failed. Run as Administrator!");
            return;
        }

        Pointer addr = new Memory(256);
        IntByReference readLenRef = new IntByReference();

        System.out.println("WinDivert sidecar running...");

        byte[] packetBuf = new byte[MAX_PACKET_LEN];
        while (true) {
            try {
                boolean success = WinDivert.INSTANCE.WinDivertRecv(handle, packetBuf, MAX_PACKET_LEN, readLenRef, addr);
                if (!success) continue;

                int packetLen = readLenRef.getValue(); // 保证无符号

                // 安全检查长度
                if (packetLen <= 0 || packetLen > MAX_PACKET_LEN) {
                    System.err.println("Invalid packet length: " + packetLen);
                    continue;
                }

                Span span = tracer.spanBuilder("winDivertUdpHandler")
                        .setAttribute("network.protocol", "udp")
                        .startSpan();
                try (Scope scope = span.makeCurrent()) {
                    System.out.println("traceId: " + span.getSpanContext().getTraceId() + ", spanId: "
                            + span.getSpanContext().getSpanId() + ", flag: " + span.getSpanContext().getTraceFlags());
                    IntByReference writeLen = new IntByReference();
                    byte[] newBytes = PacketUtil.editUdpPacket(packetBuf);
                    if (newBytes == null) {
                        continue;
                    }
                    boolean sent = WinDivert.INSTANCE.WinDivertSend(handle, newBytes, newBytes.length, writeLen, addr);
                    if (!sent) {
                        System.err.println("Failed to inject packet");
                    } else {
                        System.out.println("Packet captured & injected, length=" + writeLen.getValue());
                    }
                } finally {
                    span.end();
                }


            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    // 初始化 OpenTelemetry SDK 并注册全局 Tracer
    private static void initOpenTelemetry() {
        // OTLP exporter (gRPC)，endpoint 以环境变量或常量为准
        OtlpGrpcSpanExporter exporter = OtlpGrpcSpanExporter.builder()
                .setEndpoint(Config.oltpEndPoint)
                .build();

        // Resource（service.name）
        Resource resource = Resource.getDefault()
                .merge(Resource.create(Attributes.of(AttributeKey.stringKey("service.name"), "udp-sidecar")));

        SdkTracerProvider tracerProvider = SdkTracerProvider.builder()
                .setResource(resource)
                .addSpanProcessor(BatchSpanProcessor.builder(exporter).build())
                .build();

        OpenTelemetrySdk.builder()
                .setTracerProvider(tracerProvider)
                .setPropagators(ContextPropagators.create(W3CTraceContextPropagator.getInstance()))
                .buildAndRegisterGlobal();

        tracer = GlobalOpenTelemetry.getTracer("udp-sidecar");
        System.out.println("OpenTelemetry initialized, OTLP endpoint = " + Config.oltpEndPoint);
    }

}

opentelemetry-->skywalking oap directly, no other collector.Config.oltpEndPoint=http://192.168.163.128:11800
but it seems like failed, no error in java program, no trace in skywalking.
I read update record like this "https://www.mail-archive.com/notifications%40skywalking.apache.org/msg213462.html", it mentioned that skywalking can receive otel trace?

what happend about it, how to figure it out.

[wu-sheng]

It can be collected, https://skywalking.apache.org/docs/main/latest/en/setup/backend/otlp-trace/

But it is a zipkin-like format. So it could only be queried by zipkin query API, and available in lens UI. Further, don't expect to analysis metrics and topology from it. It is not proper to do that. From otlp perspective, trace is trace.