I am using Tapestry 5, Smack api 3.1.0.
I have established a connection and am able to communicate with a user through the xmpp server but the replies i get are sent to the standard output as they come in:
Chat chat = connection.getChatManager().createChat("blah#jabber.org", new MessageListener() {
public void processMessage(Chat chat, Message message) {
// Print out any messages we get back to standard out.
System.out.println("Received message: " + message.getBody()); // this works
showonbrowser = message.getBody();
System.out.println(showonbrowser) // this prints nothing
}
};
I am looking to get the replies to my html file so i can read them on the web instead of the console. However, when i try to set message.getBody() to showonbrowser (a property on the page) i see no result. Does anyone know how I get around this?
Regards,
Kace
Smack is multi-threading and it has a nasty habit of eating up exceptions that are thrown (silently.) Most likely you are not using a thread-safe GUI and its throwing an exception that you never get.
I think the processMessage method is being called after the page is rendered.
You are creating a MessageListener instance (through an anonymous class), so you don't know when the processMessage method will be called. I think you would have to do something with AJAX to do partial updates on the page, polling the server and getting any new messages to show them on the page.
Related
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 have an application using MQTT implemented with the paho-mqtt-1.0.2 and I am using ActiveMQ as the broker. I have a class implementing the MqttCallback, what I am wondering is why does the client hang
#Override
messageArrived(...)
do work
mqtt.publish(TOPIC,PAYLOAD,2,false) <- here
I want to send a "response" message to the broker for the next step of the work to be done. Similar to this, I read in the docs for that callback function
It is possible to send a new message within an implementation of this callback (for example, a response to this message), but the implementation must not disconnect the client, as it will be impossible to send an acknowledgment for the message being processed, and a deadlock will occur.
Has anyone out there tried doing the above and get it to work?
I also tried using the MqttAsyncClient and that ended up with
"Error too many publishes in progress" leading to undelivered messages.
I know how to get around this issue, I'm not looking for workaround; I'm looking for receiving and publishing on the thread where messageArrived() gets executed.
Happy Hunting!
I'm working on a websocket implementation that collects data from several (around 10) android clients.
So I have created a classic ServerEndpoint running currently on localhost and on client side an app that opens up a connection to the ServerEndpoint and sends sensor data every 500ms.
The whole thing works fine and on time if I use just one client.
However if I use multiple clients, they send their messages all on time, but the ServerEndpoints onMessage is called at random times. It looks like it "queues" messages from a clients for several seconds, and then fires the onMessage method 5 times in a row. I would need it always on the exact time however. Can I force this?
No errors or exceptions showing up.
This is the very basic server side:
#ServerEndpoint("/ServerEndpoint")
public class ServerEndpoint {
static Set<Session> connections = Collections.synchronizedSet(new HashSet<Session>());
#OnOpen
public void handleOpen(Session userSession){
log("opened session: "+ userSession);
connections.add(userSession);
}
#OnMessage
public void handleMessage(String message, Session userSession) throws IOException{
String userName = (String) userSession.getUserProperties().get("username");
log("received message from: "+ userName+": "+Calendar.getInstance().get(Calendar.SECOND)+":"+Calendar.getInstance().get(Calendar.MILLISECOND)+ " "+ message );
....
}
#OnClose
public void handleClose(Session userSession){
log("closed session: "+userSession);
connections.remove(userSession);
}
I guess I miss some configuration option of the ServerEndpoint or something. Does someone know what causes this behavior and how to solve it?
Alright got it. The issue was Tomcat 7 which has obviously some issues with websockets. Using Tomcat 8, it works now without any queues or big delay. Also other minor errors and connection problems were solved by the update and it seems to be much more stable.
Maybe this helps someone facing similar problems.
I am new here so forgive me if I am not familiar with standard operating procedure, but I have researched this topic at length and haven't found a lot of info.
I am trying to implement a client in a Java Http Servlet that can subscribe to a server-sent-event stream and parse data from that stream. Every time I have a client POST a request to my Http servlet, I need to pass on some data from that client to another server and then open an SSE listener, as that is how the other server will notify me it has data for me to hand back to the client.
It needs to be asynchronous and probably multi-threaded because I will have many requests from the client happening in a short time frame and I need to catch every event coming back from the server. The data I pass back from the server to the client can be large so I need threading so I don't miss new events coming in.
I am at a loss for where to start. I have tried implementing some of the example code using the Jersey SSE API (https://jersey.java.net/documentation/latest/sse.html) but when I implement their asynchronous SSE event handling example, the events coming in happen too fast for my handler to process all the data back to the client and the function gets called again from a new event before it finishes, or at least that's what seems to be happening.
Here is a synopsis of what I have written so far:
Client client = ClientBuilder.newBuilder().register(SseFeature.class).build();
WebTarget target = client.target("Target URL");
EventSource eventSource = new EventSource(target) {
#Override
public void onEvent(InboundEvent inboundEvent){
if ("in".equals(inboundEvent.getName())) {
//Check if the event is of the type we care about
//If it is, open an input stream to read the payload and store in a byte array via an HttpURLConnection object
//Open an output stream and stream the payload to a client via an HttpServletResponse Object - This never seems to happen
}
}
};
}
I know it's sloppy, I'm not as familiar with Java so I am just piecing things together so I apologize for that.
This gets called from within my servlet class but it never makes it to the point where I write to the output stream, I think because it's getting interrupted by another event coming in. If anyone has insight into how I can make this work, or another way to do it, I would greatly appreciate it. Thanks.
I recommend you the JEaSSE library (Java Easy Server-Sent Events): http://mvnrepository.com/artifact/info.macias/jeasse
You can find some usage examples here:
https://github.com/mariomac/jeasse
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!