xSub socket subscription throws IllegalArgumentException

[komape]

My system has a broker with two sockets, one xPub and one xSub. When I try to subscribe the xSub socket to all topics I get an IllegalArgumentException with the error message Unknown Option 6. It looks like that the subscription command is internally mapped to the number 6. But there is no switch case option that handles the number 6.

ZMQ.Socket xSubSocket = context.createSocket(SocketType.XSUB);
xSubSocket.bind(X_SUB_ADDRESS);
xSubSocket.subscribe(""); // subscribe to all

Exception in thread "main" java.lang.IllegalArgumentException: Unknown Option 6
    at zmq.Options.setSocketOpt(Options.java:547)
    at zmq.SocketBase.setSocketOpt(SocketBase.java:234)
    at org.zeromq.ZMQ$Socket.setSocketOpt(ZMQ.java:910)
    at org.zeromq.ZMQ$Socket.subscribe(ZMQ.java:2113)

What's the recommended way to handle this?

[Muspah]

Bit late, but calling socket#subscribe() on an XSUB socket doesn't work indeed. We've fixed it like:

for (String sub : subscriptions) {
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    bos.writeBytes(new byte[]{0x01});
    bos.writeBytes(sub.getBytes(StandardCharsets.UTF_8));
    socket.send(bos.toByteArray());
}

Btw, we're using socket#connect() instead of socket#bind() on an XSUB, but I'm not sure about the reasoning behind that anymore.