We Keep Coding

Behaviour setTimeToWait() method in java paho library

I use library paho for connectivity with mqtt broker, sending messages and almost everything work fine, but i have problem with setTimeToWait() method. it does not metter how many milliseconds i put into method setTimeToWait(2000) or setTimeToWait(10). I always get messages from publiusher.
Why can i get messages within the hours? If i set waiting time 2000 milliseconds. I thought after 2 secs absence of messages from publisher my subscriber cannot get messages from publiser and control will be returned.
What Am i doing wrong?
Publisher code:
public class MqttPublishSample {
public static void main(String[] args) throws MqttException {
String messageString = "{\"device_status\": \"ready\"}";
if (
args.length == 2 ) {
messageString = args[1];
}
System.out.println("== START PUBLISHER ==");
MqttClient client = new MqttClient("tcp://localhost:1883" , MqttClient.generateClientId());
client.connect();
MqttMessage message = new MqttMessage();
message.setPayload(messageString.getBytes());
message.setQos(1);
client.publish("/catalog", message);
System.out.println("\tMessage '"+ messageString +"' to 'iot_data'");
client.disconnect();
System.out.println("== END PUBLISHER ==");
}
}
Subscriber code:
public class MqttSuscribeSample {
public static void main(String[] args) {
System.out.println("== START SUBSCRIBER ==");
try{
MqttClient client=new MqttClient("tcp://localhost:1883", MqttClient.generateClientId());
client.setTimeToWait(2000);
client.setCallback( new SimpleMqttCallback() );
client.connect();
client.subscribe( "/catalog");
}catch (Exception ex){
ex.printStackTrace();
}
}
}
SimpleMqttCallback code
public class SimpleMqttCallback implements MqttCallback {
public void connectionLost(Throwable throwable) {
System.out.println("Connection to MQTT broker lost!");
}
public void messageArrived(String s, MqttMessage mqttMessage) throws Exception {
System.out.println("Message received:\t"+ new String(mqttMessage.getPayload()) );
}
public void deliveryComplete(IMqttDeliveryToken iMqttDeliveryToken) {
}
}

The setTimeToWait() method is how long the the client should wait for a response from the broker when carrying out specific actions e.g.
publishing a message
making a subscription
connecting or disconnecting from the broker
It is not how long the client should wait or a message to be delivered for an existing subscription.
If you want this sort of behaviour you need to run your own timer and either unsubscribe from the topic or disconnect from the broker when it times out.

SparkJava websocket not working

SparkJava web sockets won't work. Whenever I attempt to connect to it with a websocket tester, at 'ws://localhost:4567/echo' it gets an error 'undefined' and never connects, nor do any of the sout's or printStackTrace get called.
#WebSocket
public class EchoWebSocket {
private static final Queue<Session> sessions = new ConcurrentLinkedQueue<>();
#OnWebSocketConnect
public void connected(Session session) {
System.out.println("Client connected");
//sessions.add(session);
}
#OnWebSocketClose
public void closed(Session session, int statusCode, String reason) {
System.out.println("Client disconnected");
//sessions.remove(session);
}
#OnWebSocketMessage
public void message(Session session, String message) throws IOException {
System.out.println("Got: ");// + message); // Print message
//session.getRemote().sendString(message); // and send it back
}
#OnWebSocketError
public void throwError(Throwable error) {
error.printStackTrace();
}
}
how I call it
Spark.webSocket("/echo", new EchoWebSocket());
Spark.init();

You need to define the class, not create an object.
Spark.webSocket("/echo", EchoWebSocket.class);

unable to subscribe paho mqtt java

I'm new to mqtt. Getting started I tried publishing and subscribing topics to mosquitto broker. I was able to publish messages. But my subscriber is not listening to the topic, it will start and stop without waiting/polling for messages.
Here is the subscriber code,
public class MqttSubscriber implements MqttCallback {
private static final String TOPIC = "iot/endpoint";
public static void main(String[] args) {
new MqttSubscriber().listen();
}
public void listen() {
MqttClient client = null;
try {
client = MqttClientGenerator.generateSubscriberClient();
client.connect();
System.out.println("Fetching messages...");
client.subscribe(TOPIC);
client.setCallback(this);
client.disconnect();
} catch (MqttException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
public void connectionLost(Throwable t) {
t.printStackTrace();
}
public void deliveryComplete(IMqttDeliveryToken arg0) {
}
public void messageArrived(String topic, MqttMessage message) throws Exception {
System.out.println("Message received from broker...");
System.out.println("Received Message: -- ");
System.out.println(message.getPayload().toString());
}
}
MqttClientGenerator :
public class MqttClientGenerator {
private static final String BROKER_URI = "tcp://localhost:1883";
private static final String CLIENT_ID = "pub";
private static final String SUBSCRIBER_ID = "sub";
private MqttClientGenerator () {}
public static MqttClient generatePublisherClient() throws MqttException{
//adding timestamp to make client name unique every time
return new MqttClient(BROKER_URI, CLIENT_ID+new Date().getTime());
}
public static MqttClient generateSubscriberClient() throws MqttException{
//adding timestamp to make client name unique every time
return new MqttClient(BROKER_URI, SUBSCRIBER_ID+new Date().getTime());
}
}
what am i missing here?

Try deleting the line where you disconnect the client.

Netty Channel fail when write and flush too many and too fast

When I write a producer to publish message to my server. I've seen this:
java.io.IOException: Connection reset by peer
at sun.nio.ch.FileDispatcherImpl.read0(Native Method)
at sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:39)
at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:223)
at sun.nio.ch.IOUtil.read(IOUtil.java:192)
at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:384)
at io.netty.buffer.UnpooledUnsafeDirectByteBuf.setBytes(UnpooledUnsafeDirectByteBuf.java:447)
at io.netty.buffer.AbstractByteBuf.writeBytes(AbstractByteBuf.java:881)
at io.netty.channel.socket.nio.NioSocketChannel.doReadBytes(NioSocketChannel.java:242)
at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:119)
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:511)
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:468)
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:382)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:354)
at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:111)
at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:137)
at java.lang.Thread.run(Thread.java:745)
I've searched all around and was told that because of channel is closed.
But, in my code. I'm just close my channel when my channel pool destroy the channel.
Here my code:
public static class ChannelFactory implements PoolableObjectFactory<Channel> {
private final Bootstrap bootstrap;
private String host;
private int port;
public ChannelFactory(Bootstrap bootstrap, String host, int port) {
this.bootstrap = bootstrap;
this.host = host;
this.port = port;
}
#Override
public Channel makeObject() throws Exception {
System.out.println("Create new channel!!!");
bootstrap.validate();
return bootstrap.connect(host, port).channel();
}
#Override
public void destroyObject(Channel channel) throws Exception {
ChannelFuture close = channel.close();
if (close.isSuccess()) {
System.out.println(channel + " close successfully");
}
}
#Override
public boolean validateObject(Channel channel) {
System.out.println("Validate object");
return (channel.isOpen());
}
#Override
public void activateObject(Channel channel) throws Exception {
System.out.println(channel + " is activated");
}
#Override
public void passivateObject(Channel channel) throws Exception {
System.out.println(channel + " is passivated");
}
/**
* #return the host
*/
public String getHost() {
return host;
}
/**
* #param host the host to set
* #return
*/
public ChannelFactory setHost(String host) {
this.host = host;
return this;
}
/**
* #return the port
*/
public int getPort() {
return port;
}
/**
* #param port the port to set
* #return
*/
public ChannelFactory setPort(int port) {
this.port = port;
return this;
}
}
And here is my Runner:
public static class Runner implements Runnable {
private Channel channel;
private ButtyMessage message;
private MyChannelPool channelPool;
public Runner(MyChannelPool channelPool, Channel channel, ButtyMessage message) {
this.channel = channel;
this.message = message;
this.channelPool = channelPool;
}
#Override
public void run() {
channel.writeAndFlush(message.content()).syncUninterruptibly().addListener(new ChannelFutureListener() {
#Override
public void operationComplete(ChannelFuture future) throws Exception {
channelPool.returnObject(future.channel());
}
});
}
}
And my main:
public static void main(String[] args) throws InterruptedException {
final String host = "127.0.0.1";
final int port = 8080;
int jobSize = 100;
int jobNumber = 10000;
final Bootstrap b = func(host, port);
final MyChannelPool channelPool = new MyChannelPool(new ChannelFactory(b, host, port));
ExecutorService threadPool = Executors.newFixedThreadPool(1);
for (int i = 0; i < jobNumber; i++) {
try {
threadPool.execute(new Runner(channelPool, channelPool.borrowObject(), new ButtyMessage()));
} catch (Exception ex) {
System.out.println("ex = " + ex.getMessage());
}
}
}
With ButtyMessage extends ByteBufHolder.
In my Runner class, if I sleep(10) after writeAndFlush it run quite OK. But I don't want to reply on sleep. So I use ChannelFutureListener, but the result is bad. If I send about 1000 to 10.000 messages, it will crash and throw exception above. Is there any way to avoid this?
Thanks all.
Sorry for my bad explain and my English :)

You have several issues that could explain this. Most of them are related to wrong usage of asynchronous operations and future usage.
I don't know if it could be in link with your issue but, if you really want to print when the channel is really closed, you have to wait on the future, since the future on close() (or any other operations) immediately returns, without waiting for the real close. Therefore your test if (close.isSuccess()) shall be always false.
public void destroyObject(final Channel channel) throws Exception {
channel.close().addListener(new ChannelFutureListener() {
#Override
public void operationComplete(ChannelFuture close) {
if (close.isSuccess()) {
System.out.println(channel + " close successfully");
}
}
});
}
However, as I suppose it is only for debug purpose, it is not mandatory.
Another one: you send back to your pool a channel that is not already connected (which could explain your sleep(10) maybe?). You have to wait on the connect().
public Channel makeObject() throws Exception {
System.out.println("Create new channel!!!");
//bootstrap.validate(); // this is implicitely called in connect()
ChannelFuture future = bootstrap.connect(host, port).awaitUninterruptibly();
if (future.isSuccess()) {
return future.channel();
} else {
// do what you need to do when the connection is not done
}
}
third one: validation of a connected channel might be better using isActive():
#Override
public boolean validateObject(Channel channel) {
System.out.println("Validate object");
return channel.isActive(); // instead of isOpen()
}
fourth one: in your runner, you wrongly await on the future while you should not. You can remove your syncUninterruptibly() and let the rest as is.
#Override
public void run() {
Channel.writeAndFlush(message.content()).addListener(new ChannelFutureListener() {
#Override
public void operationComplete(ChannelFuture future) throws Exception {
channelPool.returnObject(future.channel());
}
});
}
And finally, I suppose you know your test is completely sequential (1 thread in your pool), such that each client will reuse over and over the very same channel?
Could you try to change the 4 points to see if it corrects your issue?
EDIT: after requester comment
For syncUntinterruptibly(), I did not read carefully. If you want to block on write, then you don't need the extra addListener since the future is done once the sync is over. So you can directly call your channelPool.returnObject as next command just after your sync.
So you should write it this way, simpler.
#Override
public void run() {
Channel.writeAndFlush(message.content()).syncUntinterruptibly();
channelPool.returnObject(future.channel());
}
For fireChannelActive, it will be called as soon as the connect finished (so from makeObject, sometime in the future). Moreover, once disconnected (as you did have notice in your exception), the channel is no more usable and must be recreated from zero. So I would suggest to use isActive however, such that, if not active, it will be removed using destroyObject...
Take a look at the channel state model here.

Finally, I've found a solution for myself. But, I'm still think about another solution. (this solution is exactly copy from 4.0.28 netty release note)
final String host = "127.0.0.1";
final int port = 8080;
int jobNumber = 100000;
final EventLoopGroup group = new NioEventLoopGroup(100);
ChannelPoolMap<InetSocketAddress, MyChannelPool> poolMap = new AbstractChannelPoolMap<InetSocketAddress, MyChannelPool>() {
#Override
protected MyChannelPool newPool(InetSocketAddress key) {
Bootstrap bootstrap = func(group, key.getHostName(), key.getPort());
return new MyChannelPool(bootstrap, new _AbstractChannelPoolHandler());
}
};
ChannelPoolMap<InetSocketAddress, FixedChannelPool> poolMap1 = new AbstractChannelPoolMap<InetSocketAddress, FixedChannelPool>() {
#Override
protected FixedChannelPool newPool(InetSocketAddress key) {
Bootstrap bootstrap = func(group, key.getHostName(), key.getPort());
return new FixedChannelPool(bootstrap, new _AbstractChannelPoolHandler(), 10);
}
};
final ChannelPool myChannelPool = poolMap.get(new InetSocketAddress(host, port));
final CountDownLatch latch = new CountDownLatch(jobNumber);
for (int i = 0; i < jobNumber; i++) {
final int counter = i;
final Future<Channel> future = myChannelPool.acquire();
future.addListener(new FutureListener<Channel>() {
#Override
public void operationComplete(Future<Channel> f) {
if (f.isSuccess()) {
Channel ch = f.getNow();
// Do somethings
ch.writeAndFlush(new ButtyMessage().content()).addListener(new ChannelFutureListener() {
#Override
public void operationComplete(ChannelFuture future) throws Exception {
if (future.isSuccess()) {
System.out.println("counter = " + counter);
System.out.println("future = " + future.channel());
latch.countDown();
}
}
});
// Release back to pool
myChannelPool.release(ch);
} else {
System.out.println(f.cause().getMessage());
f.cause().printStackTrace();
}
}
});
}
try {
latch.await();
System.exit(0);
} catch (InterruptedException ex) {
System.out.println("ex = " + ex.getMessage());
}
As you can see, I use SimpleChannelPool and FixedChannelPool (an implementation of SimpleChannelPool provided by netty).
What it can do:
SimpleChannelPool: open channels as much as it need ---> if you has 100.000 msg -> cuz error, of course. Many socket open, then IOExeption: Too many file open occur. (is that really pool? Create as much as possible and throw exception? I don't call this is pooling)
FixedChannelPool: not work in my case (Still study why? =)) Sorry for my stupidness)
Indeed, I want to use ObjectPool instead. And I may post it as soon as when I finish. Tks #Frederic Brégier for helping me so much!

Howto add request header to Tyrus annotation based client

I'm trying to access a websocket server endpoint using a tyrus standalone client (tyrus-standalone-client-1.9) with an annotation based client endpoint. I was mainly following this example.
That is, my client endpoint currently looks like
#ClientEndpoint
public class MyClientEndpoint {
private static CountDownLatch latch;
private Logger logger = Logger.getLogger(this.getClass().getName());
#OnOpen
public void onOpen(Session session) throws Exception {
session.getBasicRemote().sendText("initialRequest")
}
#OnMessage
public void onMessage(String message, Session session) throws Exception {
// do something
}
#OnClose
public void onClose(Session session, CloseReason closeReason) {
logger.info(String.format("Session %s close because of %s", session.getId(), closeReason));
latch.countDown();
}
public static void main(String[] args) {
latch = new CountDownLatch(1);
ClientManager client = ClientManager.createClient();
try {
URI serverEndpointUri = new URI("ws://localhost/websockets/server/endpoint");
client.connectToServer(MyClientEndpoint.class, serverEndpointUri);
latch.await();
} catch (DeploymentException | URISyntaxException | InterruptedException e) {
throw new RuntimeException(e);
}
}
}
However I need to pass some session ID along with the request and I need to modify the origin header of the request to get my connection accepted by the server endpoint.
In a programmatic client endpoint I could do something like
final Builder configBuilder = ClientEndpointConfig.Builder.create();
configBuilder.configurator(new Configurator() {
#Override
public void beforeRequest(final Map<String, List<String>> headers) {
headers.put("Cookie", Arrays.asList("X-Session=0f822c8c-bf63-4ae7-9d2f-af263f86baad"));
headers.put("Origin", Arrays.asList("http://localhost"));
}
});
ClientEndpointConfig clientConfig = configBuilder.build();
ClientManager client = ClientManager.createClient();
URI serverEndpointUri = new URI("ws://localhost/websockets/server/endpoint");
client.connectToServer(new MyClientEndpoint(), clientConfig, serverEndpointUri);
But there doesn't seem to be any option to pass the configuration to an annotation based client.
Is there some other way to add/modify the request headers that I'm currently missing? I'd really like to stay with the annotation based approach as it seems to be much cleaner to me...

See ModifyRequestResponseHeadersTest.java:183
#ClientEndpoint(configurator = MyClientConfigurator.class)
public static class MyClientEndpoint {
public static final CountDownLatch messageLatch = new CountDownLatch(1);
public static volatile String receivedMessage;
#OnOpen
public void onOpen(Session session) throws IOException {
session.getBasicRemote().sendText(SENT_MESSAGE);
}
#OnMessage
public void onMessage(String message) {
receivedMessage = message;
messageLatch.countDown();
}
}
And MyClientConfigurator:
public static class MyClientConfigurator extends ClientEndpointConfig.Configurator {
static volatile boolean called = false;
#Override
public void beforeRequest(Map<String, List<String>> headers) {
called = true;
headers.put(HEADER_NAME, Arrays.asList(HEADER_VALUE));
headers.put("Origin", Arrays.asList("myOrigin"));
}
#Override
public void afterResponse(HandshakeResponse handshakeResponse) {
final Map<String, List<String>> headers = handshakeResponse.getHeaders();
assertEquals(HEADER_VALUE[0], headers.get(HEADER_NAME).get(0));
assertEquals(HEADER_VALUE[1], headers.get(HEADER_NAME).get(1));
assertEquals(HEADER_VALUE[2], headers.get(HEADER_NAME).get(2));
assertEquals("myOrigin", headers.get("origin").get(0));
}
}