I just started with java and minecraft modding. I want to implement a very simple task but unfortunately I do not know the right event for it.
Messages sent via
Minecraft.getMinecraft().player.sendChatMessage(message);
from the client to the server I can use:
public void onChat(ClientChatReceivedEvent event)
to read it back in.
However, there are now also messages that are sent via
Minecraft.getMinecraft().player.sendMessage(m)
only direct to the client. Is there also a possibility to read these messages? Another mod writes these "client only" messages that I want to respond to.
You can. You have to read output packet that contains sent messages like that :
#Inject(method = "sendPacket(Lnet/minecraft/network/Packet;)V", at = #At("HEAD"), cancellable = true)
private void onSendPacket(Packet<?> packet, CallbackInfo callbackInfo) {
// System.out.println("Packet Sent: " + packet.toString());
// here you can get the packet type, then if it's chat's you can get content
// you can cancel it with: callbackInfo.cancel();
}
Source
Related
Currently have a TCP server built in Java and I'm sending messages/packets out to clients using their socket's OutputStream:
// Send all player's information to everyone else
outerPlayerIter = players.iterator();
while(outerPlayerIter.hasNext()) {
Player outerPlayer = outerPlayerIter.next();
Iterator<Player> innerPlayerIter = players.iterator();
while(innerPlayerIter.hasNext()) {
Player innerPlayer = innerPlayerIter.next();
boolean isYou = false;
if(innerPlayer.equals(outerPlayer)) isYou = true;
// Send innerPlayer's info to outerPlayer
Thread.sleep(100);
dataBuffer.clearBuffer();
dataBuffer.writeByte(Msgs.mm_toclient.MES_SENDPLAYERINFO);
dataBuffer.writeBool(isYou);
dataBuffer.writeBool(innerPlayer.getIsHost());
dataBuffer.writeString(innerPlayer.getName());
dataBuffer.writeString(innerPlayer.getPublicIP().getHostAddress());
dataBuffer.writeShort((short)innerPlayer.getUdpPort());
outerPlayer.getSocket().getOutputStream().write(dataBuffer.getByteArray());
outerPlayer.getSocket().getOutputStream().flush();
}
}
However, sometimes the clients don't appear to receive all the messages. I can't send multiple messages at the exact same time over one socket.
One way to temporarily fix this was to sleep before I send another packet out. But I'm not sure why this is needed.
Am I doing something wrong in regards to how I'm sending/writing the packets out to be sent? What can be fixed to allow multiple packets to be received correctly at once without sleeping?
It might be due to the fact that the client closes the socket way too fast before the communication should actually finished. Could you please try to bump up the thread.sleep value or, on the client side, if you use any kind of timing, try to bump up that one as well.
So I have a one client-server based ecosystem where I am using RabbitMQ as a persistent Middleware.
Now the flow of a single message goes like this.
Step-1: Client A sends a message to the server with the destination
being set to Client B in the metadata of that message.
Step-2: Server upon receiving a message pushes the message to the
RabbitMQ and sends Client B a notification that he has some messages
to fetch.
Step-3: Client B upon getting notified calls the fetch message API to
get messages from the server.
Step-4: On the server, after getting called from the Client B pulls
messages from the RabbitMQ using the pull-based approach
(channel.basicGet(queueName, false)) and hands over the list of
messages.
Now in the above flow, there are few things that I have some doubt with.
First of all, if my client receives two notifications and calls the pull message API twice, there might be a concurrency problem.
Suppose I am not sending the message Acknowledgement while getting the message but I am sending afterwards, then can It be possible that the same message being sent to two pull API? If so is there any way to prevent this from happening?
Sample Code to Get Message From the MQ:
long currentMessageCount = channel.messageCount(QUEUE_NAME);
while (currentMessageCount-- > 0) {
GetResponse getResponse = channel.basicGet(QUEUE_NAME, false);
if (getResponse == null) {
break;
}
AMQP.BasicProperties props = getResponse.getProps();
Envelope envelope = getResponse.getEnvelope();
int messageCount = getResponse.getMessageCount();
byte[] body = getResponse.getBody();
/*
Do some logic
*/
channel.basicAck(envelope.getDeliveryTag(), false);
}
TIA
basicGet is rarely the correct solution. In Step 2, the client should be consuming from RabbitMQ. No notification that a message is ready is necessary. RabbitMQ will send the message to Client B as soon as it's in the queue. Step-3 and Step-4 become unnecessary.
NOTE: the RabbitMQ team monitors the rabbitmq-users mailing list and only sometimes answers questions on StackOverflow.
I would like to send a simple message from one client to another one not opening a chat because there will never be a response and all messages fire the same event.
In the smack (4.1.7) documentation I found out that it is possible to do so but so far I did not find a way how to do it.
Do you have any ideas how to do it?
Would it be better (especially acording to performance: runtime and memory) to use the chat?
For receiving you'd probably want to use a synchronous stanza listener with a suitable filter.For example, if you want to receive messages with a body from user#example.org, then you could
XMPPConnection connection = …;
connection.addSyncStanzaListener(new StanzaListener() {
#Override
void process(Stanza stanza) {
Message message = (Message) stanza;
// Received new message with body from user#example.org
}, new AndFilter(MessageWithBodiesFilter.INSTANCE,
FromMatchesFilter.create("user#example.org")));
Sending messages is even easier
Message message = new Message("user#example.org", "Hi, how are you?");
XMPPConnection connection = …;
connection.sendStanza(message);
Hint: Reading the source code of Smack is a great way to learn about such stuff. If you look at the source of ChatManager, you will find what I've just written above.
I'm implementing simple netty server for a multiplayer game. I'm just trying to figure out Netty.
I test the server via telnet. What i done is broadcast the messages to all channels. It's working smoothly. Also I remove channels from map on close event which is fine.
But the problem is if one of the clients disconnect unexpectedly, before closed callback, messageReceived callback called which the sender is disconnected channel.
How can i properly ignore the message comes from disconnected client?
I use StringBuffer in messagedReceived but for the case StringBuffer.toString is also not a proper string. At the end disconnected channel broadcast pointless message to other channels and itself, when receiver channel is itself throws an exception Connection reset by peer
which it's normal because the channel itself is not available at the moment.
Here is the code ;
#Override
public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) {
System.out.println();
System.out.println("------------------");
Channel current = e.getChannel();
System.out.println("SenderChannel:"+current.getId());
if(!current.isOpen())
System.out.println("Not Open");
ChannelBuffer buf = (ChannelBuffer) e.getMessage();
StringBuffer sbs = new StringBuffer();
while(buf.readable()) {
sbs.append((char) buf.readByte());
}
String s = sbs.toString();
System.out.println(s);
String you = "You:" + s;
String other = "Other:" + s;
byte [] uResponse = you.getBytes();
byte [] otherResponse = other.getBytes();
Iterator iterator = channelList.entrySet().iterator();
while(iterator.hasNext()){
Map.Entry pairs = (Map.Entry)iterator.next();
Integer key = (Integer)pairs.getKey();
Channel c = (Channel)pairs.getValue();
System.out.println("ReceiverChannel:"+c.getId());
if(key != current.getId())
c.write(ChannelBuffers.wrappedBuffer(otherResponse));
else
c.write(ChannelBuffers.wrappedBuffer(uResponse));
}
}
#Override
public void channelDisconnected(ChannelHandlerContext ctx,
ChannelStateEvent e){
Channel ch = e.getChannel();
channelList.remove(ch.getId());
System.out.println();
System.out.println("*****************");
System.out.println("DisconnectEvent:"+ch.getId());
System.out.println("*****************");
System.out.println();
ch.close();
}
You can't solve the problem in the manner that you would like. If there's a network problem then technically the sender could disconnect at any time, for example
as soon as the thread enters messageReceived
while you're iterating through channelList
while you're iterating through channelList but after you've echoed back to the sender
after you've broadcast the message
Netty can't raise the disconnected event while messageReceived is processing because you're running in the thread that will raise the event (unless you have a non-ordered execution handler in your pipeline). The correct solution really depends on your application. If the broadcast results in all the other receivers responding it's probably better / easier to have the server suppress any messages destined for a client that's no longer connected.
Also, if you're really going to use strings then take a look at StringEncoder / StringDecoder. There's no guarantee in your code that the message event buffer contains a complete string.
Just put a try/catch around each send. If one of them fails, close the corresponding channel.
If this is for a multiplayer game server, it might be better to use an existing Netty game server solution like java game server. Disconnects become events which get sent to the session and since it is event driven, you could write your own handler to decide whether or not to receive anymore events on the same session. Since events are queued in a FIFO order, if disconnect happens then you need not go ahead with subsequent broadcasts.
I am not a Java Developer. But from socket point of view this data is in buffer or sent before disconnecting of user. So when you are in receiving stage user is still connected and exactly on time of completing of receiving user is already disconnected. So I think best way to prevent this things is to check if user is still connected after each receiving of data.
In C# I personally use this code to check if user is still connected:
if (client.Poll(0, SelectMode.SelectRead))
{
byte[] checkConn = new byte[1];
if (client.Receive(checkConn, SocketFlags.Peek) == 0)
return false;
}
return true;
I am not sure about Java And Netty (And if your connection is TCP) but this is what I use and this could be possible to convert it easily to Java.
I've created a mock XMPP server that processes PLAIN encryption stanzas. I'm able to use Pidgin and go through the entire session creation, to the point where Pidgin thinks the user is on an actually XMPP server and is sending regular pings.
However, it seems like not all messages are processed correctly and when I do get a successful login, it was just luck. I'm talking, maybe 1/10th of the time I actually get connected. The other times it seems like Pidgin missed a message or I dumped messages to fast on the transport.
If I enable Pidgin's XMPP Console plugin, the first connection is ALWAYS successful, but a second user fails to make it through, typically dying when Pidgin requests Service Discovery.
My Mina code is something like this:
try
{
int PORT = 20600;
IoAcceptor acceptor = null;
acceptor = new NioSocketAcceptor();
acceptor.getFilterChain().addFirst("codec", new ProtocolCodecFilter( new ProtocolCodecFactoryImpl()));
acceptor.getFilterChain().addLast("executor", new ExecutorFilter(IoEventType.MESSAGE_RECEIVED));
acceptor.setHandler( new SimpleServerHandler());
acceptor.getSessionConfig().setIdleTime(IdleStatus.BOTH_IDLE, 10);
acceptor.bind( new InetSocketAddress(PORT));
}
catch (Exception ex)
{
System.out.println(ex.getMessage());
}
and the SimpleServerHandler is responsible for message/stanza processing and session creation. The messageReceived function looks like:
#Override
public void messageReceived(IoSession session, Object msg) throws Exception
{
String str = msg.toString();
System.out.println("MESSAGE: " + str);
process(session, str);
}
and finally, process is in charge of parsing the message out, and writing the response. I do use sychonized on my write:
public void sessionWrite(IoSession session, String buf)
{
synchronized(session)
{
WriteFuture future = session.write(buf);
}
}
I have omitted my processing code for brevity, but it simply looks for certain pieces of data, crafts a response and calls sessionWrite(...)
My question is, will this pattern work? And if not, should I consider shoving received messages in a Queue and simply processing the Queue from say a Timer?
It turns out, Pidgin would send two IQ stanzas, but I wasn't handling them correctly. My decoder now determines the end of a stanza and only writes a stanza to the buffer I read from.
Works like a dream now!