Use binder for communication between service running on vendor partition and clients running on system partition

Question

Need to do ipc between service running on vendor partition and clients running on system partition. I'm trying to use binder for the ipc, but with no luck. service code:

int main(int argc, char** argv)
{
    
    //sp<ProcessState> proc(ProcessState::self());
    //android::ProcessState::initWithDriver("/dev/vndbinder");
    
    //ALOGI("Done init vndbinder from server side\n");
    
    sp<HelloService> hello = new HelloService("HELLO-API");
    sp<IServiceManager> sm = defaultServiceManager();
    
    sm->addService(String16("hello.service"), hello);
    
    ProcessState::self()->startThreadPool();
    IPCThreadState::self()->joinThreadPool();  
    return 0;
}

client code:

int main(int argc, char** argv)
{
    //sp<ProcessState> proc(ProcessState::self());
    
    //android::ProcessState::initWithDriver("/dev/vndbinder");
    //ALOGI("Done init vndbinder from client side\n");
    
    sp<IServiceManager> sm = defaultServiceManager();
    if (sm == NULL) {
        ALOGI("can not get service manager");
    }
    
    
    sp<IBinder> b = sm->getService(String16("hello.service"));

    if (b == 0)
    {
        ALOGI("can't get hello service\n");
        return -1;
    }
    else
    {
        ALOGI("we get hello service\n");    
    }
    
    sp<IHello> hello(interface_cast<IHello>(b));

    if (hello == NULL) {
        ALOGI("can not cast interface");
    }
    ... 

If I run the server and client both from system/bin folder, I do see the communication. But if I run the server from vendor/bin folder and the client from system/bin folder, it always gives errors "ProcessState: Not able to get context object on /dev/vndbinder.".

Thanks for any suggestions!