@Override
    public void prepare() {
        serviceId = IDManager.ServiceID.buildId(serviceName, serviceLayer.isNormal());
        relatedServiceId = IDManager.ServiceID.buildId(relatedServiceName, relatedServiceLayer.isNormal());
    }
The service layer of the lower service.
oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/hierarchy/service/ServiceHierarchyRelation.java