In the code below I would like the subscriber to control when the Flowable emits an event by holding a reference to the Subscription inside subscribe() and requesting the number of elements I want to be produced.
What I am experiencing is that observeOn()'s buffer with size 2 is hiding my call to subscription.request(3) as the producer is producing 2 elements at a time instead of 3.
public class FlowableExamples {
public static void main(String[] args) throws InterruptedException {
long start = new Date().getTime();
Flowable<Integer> flowable = Flowable
.generate(() -> 0, (Integer state, Emitter<Integer> emitter) -> {
int newValue = state + 1;
log("Producing: " + newValue);
emitter.onNext(newValue);
return newValue;
})
.take(30);
flowable
.subscribeOn(Schedulers.io())
.observeOn(Schedulers.computation(), false, 2)
.subscribe(new Subscriber<Integer>() {
Subscription subscription;
#Override
public void onSubscribe(Subscription subscription) {
this.subscription = subscription;
subscription.request(5);
}
#Override
public void onNext(Integer integer) {
log("\t\treceived: " + integer);
if (integer >= 5) {
sleep(500);
log("Requesting 3 should produce 3, but actually produced 2");
subscription.request(3);
sleep(1000);
}
}
#Override
public void onError(Throwable throwable) {}
#Override
public void onComplete() {
log("Subscription Completed!!!!!!!!");
}
});
sleep(40_000);
System.out.println("Exit main after: " + (new Date().getTime() - start) + " ms");
}
private static void log(String msg) {
System.out.println(Thread.currentThread().getName() + ": " + msg);
}
private static void sleep(long ms) {
try {
Thread.sleep(ms);
} catch (InterruptedException e) {}
}
}
How could I accomplish this?
I am using this example Flink CEP where I am separating out the data as I have created one application which is Sending application to Kafka & another application reading from Kafka... I generated the producer for class TemperatureWarning i.e. in Kafka,I was sending data related to TemperatureWarning Following is my code which is consuming data from Kafka...
StreamExecutionEnvironment env=StreamExecutionEnvironment.getExecutionEnvironment();
env.setStreamTimeCharacteristic(TimeCharacteristic.EventTime);
env.enableCheckpointing(5000);
Properties properties=new Properties();
properties.setProperty("bootstrap.servers", "PUBLICDNS:9092");
properties.setProperty("zookeeper.connect", "PUBLICDNS:2181");
properties.setProperty("group.id", "test");
DataStream<TemperatureWarning> dstream=env.addSource(new FlinkKafkaConsumer09<TemperatureWarning>("MonitoringEvent", new MonitoringEventSchema(), properties));
Pattern<TemperatureWarning, ?> alertPattern = Pattern.<TemperatureWarning>begin("first")
.next("second")
.within(Time.seconds(20));
PatternStream<TemperatureWarning> alertPatternStream = CEP.pattern(
dstream.keyBy("rackID"),
alertPattern);
DataStream<TemperatureAlert> alerts = alertPatternStream.flatSelect(
(Map<String, TemperatureWarning> pattern, Collector<TemperatureAlert> out) -> {
TemperatureWarning first = pattern.get("first");
TemperatureWarning second = pattern.get("second");
if (first.getAverageTemperature() < second.getAverageTemperature()) {
out.collect(new TemperatureAlert(second.getRackID(),second.getAverageTemperature(),second.getTimeStamp()));
}
});
dstream.print();
alerts.print();
env.execute("Flink Kafka Consumer");
But when I execute this application,it throws following Exception:
Exception in thread "main" java.lang.NullPointerException
at org.apache.flink.api.common.operators.Keys$ExpressionKeys.<init>(Keys.java:329)
at org.apache.flink.streaming.api.datastream.DataStream.keyBy(DataStream.java:274)
at com.yash.consumer.KafkaFlinkConsumer.main(KafkaFlinkConsumer.java:49)
Following is my class TemperatureWarning :
public class TemperatureWarning {
private int rackID;
private double averageTemperature;
private long timeStamp;
public TemperatureWarning(int rackID, double averageTemperature,long timeStamp) {
this.rackID = rackID;
this.averageTemperature = averageTemperature;
this.timeStamp=timeStamp;
}
public TemperatureWarning() {
this(-1, -1,-1);
}
public int getRackID() {
return rackID;
}
public void setRackID(int rackID) {
this.rackID = rackID;
}
public double getAverageTemperature() {
return averageTemperature;
}
public void setAverageTemperature(double averageTemperature) {
this.averageTemperature = averageTemperature;
}
public long getTimeStamp() {
return timeStamp;
}
public void setTimeStamp(long timeStamp) {
this.timeStamp = timeStamp;
}
#Override
public boolean equals(Object obj) {
if (obj instanceof TemperatureWarning) {
TemperatureWarning other = (TemperatureWarning) obj;
return rackID == other.rackID && averageTemperature == other.averageTemperature;
} else {
return false;
}
}
#Override
public int hashCode() {
return 41 * rackID + Double.hashCode(averageTemperature);
}
#Override
public String toString() {
//return "TemperatureWarning(" + getRackID() + ", " + averageTemperature + ")";
return "TemperatureWarning(" + getRackID() +","+averageTemperature + ") "+ "," + getTimeStamp();
}
}
Following is my class MonitoringEventSchema :
public class MonitoringEventSchema implements DeserializationSchema<TemperatureWarning>,SerializationSchema<TemperatureWarning>
{
#Override
public TypeInformation<TemperatureWarning> getProducedType() {
// TODO Auto-generated method stub
return null;
}
#Override
public byte[] serialize(TemperatureWarning element) {
// TODO Auto-generated method stub
return element.toString().getBytes();
}
#Override
public TemperatureWarning deserialize(byte[] message) throws IOException {
// TODO Auto-generated method stub
if(message!=null)
{
String str=new String(message,"UTF-8");
String []val=str.split(",");
TemperatureWarning warning=new TemperatureWarning(Integer.parseInt(val[0]),Double.parseDouble(val[1]),Long.parseLong(val[2]));
return warning;
}
return null;
}
#Override
public boolean isEndOfStream(TemperatureWarning nextElement) {
// TODO Auto-generated method stub
return false;
}
}
Now what is required to do keyBy operation as I have mentioned the key which is required for stream to partition ?? What needs to be done here to solve this error ??
The problem is in this function:
#Override
public TypeInformation<TemperatureWarning> getProducedType() {
// TODO Auto-generated method stub
return null;
}
you cannot return null here.
I'm new to socket programming and Netty framework. I was trying to modify the Echo Server example so that the message is not sent from client as soon as a message is received, but a call from another thread would trigger the client send a message to the server.
The problem is, the server does not get the message unless the client sends it from readChannel or MessageReceived or channelActive which are where the server is specified with a parameter (ChannelHandlerContext). I couldn't manage to find a way to save the server channel and send a message later and repeatedly.
Here's my Client Handler code;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
public class EchoClientHandler extends ChannelHandlerAdapter {
ChannelHandlerContext server;
#Override
public void channelActive(ChannelHandlerContext ctx) {
this.server = ctx;
}
#Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
// ctx.write(msg); //not
}
#Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
//ctx.flush();
}
public void externalcall(String msg) throws Exception {
if(server!=null){
server.writeAndFlush("[" + "] " + msg + '\n');
}
}
#Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
// Close the connection when an exception is raised.
ctx.close();
}
}
When Client creates the handler, it also creates a thread with a "SourceGenerator" object which gets the handler as parameter so as to call the externalcall() method.
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
/**
* Sends one message when a connection is open and echoes back any received
* data to the server. Simply put, the echo client initiates the ping-pong
* traffic between the echo client and server by sending the first message to
* the server.
*/
public class EchoClient {
private final String host;
private final int port;
public EchoClient(String host, int port, int firstMessageSize) {
this.host = host;
this.port = port;
}
public void run() throws Exception {
// Configure the client.
EventLoopGroup group = new NioEventLoopGroup();
final EchoClientHandler x = new EchoClientHandler();
SourceGenerator sg = new SourceGenerator(x);
new Thread(sg).start();
try {
Bootstrap b = new Bootstrap();
b.group(group)
.channel(NioSocketChannel.class)
.option(ChannelOption.TCP_NODELAY, true)
.handler(new ChannelInitializer<SocketChannel>() {
#Override
public void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addLast(x);
}
});
// Start the client.
ChannelFuture f = b.connect(host, port).sync();
// Wait until the connection is closed.
f.channel().closeFuture().sync();
} finally {
// Shut down the event loop to terminate all threads.
group.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
// Print usage if no argument is specified.
if (args.length < 2 || args.length > 3) {
System.err.println(
"Usage: " + EchoClient.class.getSimpleName() +
" <host> <port> [<first message size>]");
return;
}
// Parse options.
final String host = args[0];
final int port = Integer.parseInt(args[1]);
final int firstMessageSize;
if (args.length == 3) {
firstMessageSize = Integer.parseInt(args[2]);
} else {
firstMessageSize = 256;
}
new EchoClient(host, port, firstMessageSize).run();
}
}
and the SourceGenerator class;
public class SourceGenerator implements Runnable {
public String dat;
public EchoClientHandler asd;
public SourceGenerator(EchoClientHandler x) {
asd = x;
System.out.println("initialized source generator");
dat = "";
}
#Override
public void run() {
try{
while(true){
Thread.sleep(2000);
dat += "a";
asd.externalcall(dat);
System.out.print("ha!");
}
}catch(Exception e){
e.printStackTrace();
}
}
}
Thanks in advance!
If you want to write a String you need to have the StringEncoder in the ChannelPipeline.
Otherwise you can only send ByteBuf instances.
I am developing chat application by using Openfire XMPP server. I can text chat between two user. But i want to know Typing status when some one is typing message. So i created a class :-
public class typingStatus implements ChatStateListener {
#Override
public void processMessage(Chat arg0, Message arg1) {
// TODO Auto-generated method stub
}
#Override
public void stateChanged(Chat arg0, ChatState arg1) {
// TODO Auto-generated method stub
System.out.println(arg0.getParticipant() + " is " + arg1.name());
}
}
But i am confuse so that How will it work? I know that i need a packet where i can it in Listener. But i am unable to find that packet.
Please any one suggest, How will it work?
and also what is difference between Smack and asmack?
Thank you!
To enable ChatStateListener you need to create a custom MessageListener Class
public class MessageListenerImpl implements MessageListener,ChatStateListener {
#Override
public void processMessage(Chat arg0, Message arg1) {
System.out.println("Received message: " + arg1);
}
#Override
public void stateChanged(Chat arg0, ChatState arg1) {
if (ChatState.composing.equals(arg1)) {
Log.d("Chat State",arg0.getParticipant() + " is typing..");
} else if (ChatState.gone.equals(arg1)) {
Log.d("Chat State",arg0.getParticipant() + " has left the conversation.");
} else {
Log.d("Chat State",arg0.getParticipant() + ": " + arg1.name());
}
}
}
Then you create MessageListener object
MessageListener messageListener = new MessageListenerImpl();
And then pass this in the create chat method
Chat newChat = chatmanager.createChat(jabber_id_of_friend, messageListener);
what is difference between Smack and asmack? <-- Check This
finally I got the solution. I need to use chat listener along with chat manager and also I need to use in built sendcomposingnotification function. No need to use Messageeventrequestlistener interface or any other custom class for this. I added the following lines,,
connection.getChatManager().addChatListener(new ChatManagerListener() {
#Override
public void chatCreated(final Chat arg0, final boolean arg1) {
// TODO Auto-generated method stub
arg0.addMessageListener(new MessageListener()
{
#Override
public void processMessage(Chat arg0, Message arg1)
{
// TODO Auto-generated method stub
Log.d("TYpe Stat",title[0] + " is typing......");
Toast.makeText(getApplicationContext(),title[0] + " is typing......",Toast.LENGTH_SHORT).show();
}
}
});
}
});
and also need to send notification like this..
mem.sendComposingNotification(etRecipient.getText().toString(), message.getPacketID());
System.out.println("Sending notification");
where mem is type of MessageEventManger.
Ref: http://www.igniterealtime.org/builds/smack/docs/latest/javadoc/org/jivesoftware/smackx/MessageEventManager.html
ChatManager chatManager = ChatManager.getInstanceFor(connection);
Chat chat= chatManager.createChat(to, new ChatStateListener() {
#Override
public void stateChanged(Chat chat, ChatState state) {
switch (state){
case active:
Log.d("state","active");
break;
case composing:
Log.d("state","composing");
break;
case paused:
Log.d("state","paused");
break;
case inactive:
Log.d("state","inactive");
break;
case gone:
Log.d("state","gone");
break;
}
}
#Override
public void processMessage(Chat chat, Message message) {
Log.d("processMessage","processMessage");
}
});
use this code.hope so will work
i am using chat state listener :
Chat chat = chatManager.createChat(jid,
new ChatStateChangedListener());
bind the chatstatelistener with each jid like above , then :
public class ChatStateChangedListener implements ChatStateListener {
public ChatStateChangedListener() {
printLog("Chat State Changed Listner Constructor");
}
#Override
public void processMessage(Chat arg0, Message arg1) {
}
#Override
public void stateChanged(Chat chat, ChatState state) {
if (state.toString().equals(ChatState.composing.toString())) {
tvLastSeen.setText("Typing...");
} else if (state.toString().equals(ChatState.paused.toString())) {
tvLastSeen.setText("paused...");
} else {
tvLastSeen.setText("nothing");
}
}
}
}
Create On Class MMessageListener to listen incoming messages
private class MMessageListener implements MessageListener, ChatStateListener {
public MMessageListener(Context contxt) {
}
#Override
public void stateChanged(Chat chat, ChatState chatState) {
mStatus = "Online";
if (ChatState.composing.equals(chatState)) {
mStatus = chat.getParticipant() + " is typing..";
Log.d("Chat State", chat.getParticipant() + " is typing..");
} else if (ChatState.gone.equals(chatState)) {
Log.d("Chat State", chat.getParticipant() + " has left the conversation.");
mStatus = chat.getParticipant() + " has left the conversation.";
} else if (ChatState.paused.equals(chatState)){
Log.d("Chat State", chat.getParticipant() + ": " + chatState.name());
mStatus = "Paused";
}else if (ChatState.active.equals(chatState)){
mStatus = "Online";
}
// do whatever you want to do once you receive status
}
#Override
public void processMessage(Message message) {
}
#Override
public void processMessage(Chat chat, Message message) {
}
}
Add Listener to your chat object
Chat Mychat = ChatManager.getInstanceFor(connection).createChat(
"user2#localhost"),
mMessageListener);
Send status to receiving user on edittext text change
ChatStateManager.getInstance(connection).setCurrentState(ChatState.composing, Mychat);
This works fine for me.
Your or another xmpp client which you use, should sending chat state for You can catch the state.
Like This;
try {
ChatStateManager.getInstance(GlobalVariables.xmppManager.connection).setCurrentState(ChatState.composing, chat);
} catch (XMPPException e) {
e.printStackTrace();
}
or
try {
ChatStateManager.getInstance(GlobalVariables.xmppManager.connection).setCurrentState(ChatState.gone, chat);
} catch (XMPPException e) {
e.printStackTrace();
}
However you can get it from ProcessPacket also.
there you will get a Message object, after you can extract xml portion from there and handle them its contain specific chatstate or not.
Message message = (Message) packet;
String msg_xml = message.toXML().toString();
if (msg_xml.contains(ChatState.composing.toString())) {
//handle is-typing, probably some indication on screen
} else if (msg_xml.contains(ChatState.paused.toString())) {
// handle "stopped typing"
} else {
// normal msg
}
now handle as per your requirement.
Just add ChatStateManager after ChatManager intalization:
chatManager = ChatManager.getInstanceFor(getXmpptcpConnection());
ChatStateManager.getInstance(getXmpptcpConnection());
Then you need to add ChatStateListener during createChat(to,chatMesageListener):
chatManager.createChat(message.getTo(), chatMessageListener).sendMessage(message);
private ChatStateListener chatMessageListener = new ChatStateListener() {
#Override
public void stateChanged(Chat chat, ChatState state) {
//State Change composing,active,paused,gone,etc
Log.d(TAG, "ChatStateListener:::stateChanged -> " + chat.toString() + " \n -> " + state.toString());
}
#Override
public void processMessage(Chat chat, Message message) {
//Incoming Message
Log.d(TAG, "ChatStateListener:::processMessage -> " + chat.toString() + " \n -> " + message.toString());
}
};
I used cometd to realize notification push, but i found out the following issue :
After log in the system, at the beginning, the client can receive message from server, but after wait pretty long time or do some other operation, the client may not receive message from server any more. Did anyone else encountered this problem? Thanks in Advance.
Blow is my code :
1. Client Code
var cometd = dojox.cometd;cometd.websocketEnabled = false;
cometd.init(url);
cometd.subscribe("/foo/new", function(message) {
......The business logic......
}
);
2. The ServletContextAttributeListener that integrate with AbstractService
public class BayeuxInitializerListener implements ServletContextAttributeListener {
private static final String CLIENT_CHANNEL = "/foo/new";
#Override
public void attributeAdded(ServletContextAttributeEvent event) {
if(BayeuxServer.ATTRIBUTE.equals(event.getName())) {
BayeuxServer bayeuxServer = (BayeuxServer) event.getValue();
boolean isCreated = bayeuxServer.createIfAbsent(CLIENT_CHANNEL, new ConfigurableServerChannel.Initializer() {
#Override
public void configureChannel(ConfigurableServerChannel channel) {
channel.setPersistent(true);
}
});
new MyService(bayeuxServer);
}
}
3. Service
public class MyService extends AbstractService {
private static final Logger logger = Logger.getLogger(MyService .class);
private static final String CLIENT_CHANNEL = "/foo/new";
private static final String LISTENER_CHANNEL = "/service/notification";
public MyService(BayeuxServer bayeuxServer) {
super(bayeuxServer, "notification");
this.addService(LISTENER_CHANNEL, "processNotification");
}
public void processNotification(ServerSession serverSession, Map<String, Object> data) {
LocalSession localSession = this.getLocalSession();
if(logger.isDebugEnabled()) {
logger.debug("Local Session : " + localSession.getId() + ".");
}
ServerChannel serverChannel = this.getBayeux().getChannel(CLIENT_CHANNEL)
Set<ServerSession> subscribers = serverChannel.getSubscribers();
if(0 == subscribers.size()) {
logger.info("There are no subcribers for " + CLIENT_CHANNEL + ".");
}
for(ServerSession subscriber : subscribers) {
logger.info("The subscriber for " + CLIENT_CHANNEL + " : " + subscriber.getId() + ".");
}
serverChannel.publish(localSession, data, null);
}