How to consume only some chat messages of XMPP server using Smack lib ? - xmpp

I would like to know if it is possible to decide when consume a menssage from a xmmp server ?
Let me try to explain better... Imagine that i developed a bot to read all messages that the body of the message start with" MESSAGETOBOTONLY: " if i do the usual method to read a message:
public void processMessage(Chat chat, Message message) {
if (message.getType() == Message.Type.chat) { ... }
}
All messages i received will be consumed and lost... What i want is just to consume messages that start with: " MESSAGETOBOTONLY: " and let the other messages still on server to be consumed by a xmpp chat client.
best regards,

Don't abuse magic strings within a messages body element to indicate a special message type.
If you want to control a bot then use IQ packets or add an extra extension to the message type packet to indicate that this message serves a special purpose. Then you could add a packetListener with a packetFilter to get notified if these types of XMPP stanzas are received.

Related

Azure Service Bus Queue gives control characters in fetched message

I am using BizTalk Server SB-Messaging adapter to retreive messages from Azure Service Bus Queue. I have successfully managed to send message to queue myself (using same adapter), and retreive message from queue and do further processing.
Problem arises when a 3rd party software supplier is sending messages to the queue, and for BizTalk Server to retreive and process message. I then receive the following additional "header"-information and control characters in the beginning of the message:
In text: #ACKstringBShttp://schemas.microsoft.com/2003/10/Serialization/?$SOH
Seems like there is some sort of enveloped message, including headers to handle ACKnowledgement of the message to the queue.
SB-Messaging adapter gave following initial error message:
"The WCF service host at address has faulted and as a result no
more messages can be received on the corresponding receive location.
To fix the issue, BizTalk Server will automatically attempt to restart
the service host."
And, another error message:
"No Disassemble stage components can recognize the data."
Did anyone hit this problem before, and, what can be the cause of the problem? Can character encoding be a possible cause of this problem?
Here comes the feedback!
Turned out 3rd party software supplier had a setting to send message as stream, instead of string. Turns out it is a .Net application using BrokeredMessage object. Using string makes message serialized, and meta-data is added to the message. Using stream, no such serialization takes place, and message is kept untouched.
So, problem was using string and automatic serialization when sending to Service Bus Queue.
I have legacy Microsoft.ServiceBus.Messaging clients sending BrokeredMessage Xml content as <string> and I want to receive using the latest Microsoft.Azure.ServiceBus library and Message type.
Using Encoding.UTF8.GetString(message.Body) I get a unusable string prefaced with
#\u0006string\b3http://schemas.microsoft.com/2003/10/Serialization/��#
My approach is to explicitly use XmlDictionaryReader binary deserialization to undo the hidden serialization magic from the legacy library
private static string GetMessageBodyHandlingLegacyBrokeredMessage(Message message)
{
string str = null;
if (message.ContentType == null)
{
using (var reader = XmlDictionaryReader.CreateBinaryReader(
new MemoryStream(message.Body),
null,
XmlDictionaryReaderQuotas.Max))
{
var doc = new XmlDocument();
doc.Load(reader);
str = doc.InnerText;
}
}
else
throw new NotImplementedException("Unhandled Service Bus ContentType " + message.ContentType);
return str;
}
References
https://learn.microsoft.com/en-us/azure/service-bus-messaging/service-bus-messages-payloads#payload-serialization
https://carlos.mendible.com/2016/07/17/step-by-step-net-core-azure-service-bus-and-amqp/

NATS Request Reply - How it works?

I am new NATS. Not sure how NATS request reply works.
As per my understanding, this pattern can be use for bi-directional communication but questions is, Does it works between same message id/thread ? If not, can't we use two different queue for the same purpose? How it is different from pub-sub or queue pattern of NATS?
Can someone provide more use case on this?
Thanks.
You added nats-streaming-server tag, so I would first want to clarify that there is no request/reply API in NATS Streaming, because it does not really make sense.
In NATS, you would use request/reply when your publishing application wants to know that the subscribing application did receive and process the message. It is an end-to-end confirmation that the published message was received and processed.
It can also be simply because the subscribing application processes a job and send the result of that job back to the requestor.
A simple example would be:
// Request will create an internal subscription on
// a private inbox and set it to the message's Reply
// field.
msg, err := nc.Request("job", payload, time.Second)
if err != nil {
...
} else {
// msg is the reply sent by the subscribing application.
}
In the other side, you would have registered a subscription to handle the job requests.
nc.Subscribe("job", func(req *nats.Msg) {
// req is the request received by the publisher above.
// Send back a reply to the request reply subject.
nc.Publish(req.Reply, []byte(reply))
})
Not sure what language you use, but here is a link to the Go client

Same message to several services

I have one MSMQ queue which is listened by five windows services. I used BeginPeek and PeekCompleted event for this purpose. My problem is among five services, only one service is the right recipient of the message. All four just read message, but no action is performed. This can only be identified when we read MQ message.
Now, I added a code in my services to check, if the criteria matches and the message is being processed by the right service, then I am using Receive to dequeue the message from MSMQ. Is that a good idea?
Secondly, If the message doesnot satisfy condition and all five services just peeked it, but not received, the message still lies in queue. I understand. But the same message is being processed infinite times, as the message was never removed.
private void queue_PeekCompleted(object sender, PeekCompletedEventArgs e)
{
MessageQueue queue = (MessageQueue)sender;
//Message msg = queue.EndPeek(e.AsyncResult);
Message msg = e.Message;
//Read message and check if the criteria matches
if(CriteriaMatches)
{
queue.ReceiveById(e.Message.Id);
}
queue.EndPeek(e.AsyncResult);
queue.BeginPeek();
}
Appreciate your help.
Thanks,
Fayaz
Set the messages to expire after a set (short) period. They will then move to the dead letter queue where you can have another service waiting for arrivals. This service could then raise an alert, for example, as soon as a message arrives.

NETTY 4.1.4: TCP Socket Server which replies back towards clients after processing requests

i'm new to Netty and intend to create a tcp socket server which reads the info of each client and replies back towards client before processing requests immediately ,i.e. sort of an acknowledgement towards client as and when the message enters overriden channelRead method of ChannelInboundHandlerAdapter class.
Please guide me in the above specified objective.
i'm currently trying the basic netty 4.1.4 echo server example however i wanted server to send back acknowledgement to the client so i updated channelread method as follows :
#Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {
ctx.write(msg);
ChannelFuture cf = ctx.channel().write("FROM SERVER");
System.out.println("Channelfuture is "+cf);
}
and the output obtained was as follows:
Channelfuture is DefaultChannelPromise#3f4ee9dd(failure: java.lang.UnsupportedOperationException: unsupported message type: String (expected: ByteBuf, FileRegion))
I understand the error that it is expecting bytebuf but how do i achieve it? also, whether this method would be able to send out acknowledgement towards client
You can use String.getBytes(Charset) and Unpooled.wrappedBuffer(byte[]) to convert to ByteBuf.
ChannelFuture cf = ctx.channel()
.write(Unpooled.wrappedBuffer("FROM SERVER".getBytes(CharsetUtil.UTF_8)));
Also note that ctx.channel().write(...); may not be what you want. Consider ctx.write(...); instead. The difference is that if your handler is a ChannelDuplexHandler it would receive a write event when you do channel().write(). Using ctx instead of channel will send the write out from your handlers point in the pipeline instead of from the end of the pipeline, which is usually what you want.

Send XMPP (Smack) Message

Ok, the problem should be trivial but I can't get to the bottom of it.
I have two users A & B
Their JID's for this example will be A#123 and B#123 where 123 is the IP of the server.
I'm sending a message from A->B using the following code:
chat = chatmanager.createChat(username,
new MessageListener() {
public void processMessage(Chat chat, Message message) {}});
String sendUsername = username + "#123";
Message msgObj = new Message(sendUsername, Message.Type.chat);
msgObj.setBody(message);
chat.sendMessage(msgObj);
I've hardcoded the IP so that I'm 100% sure that I attach the "#123" at the end of the nickname so there are no incorrect JIDs.
So A#123 sends msgObj to B#123. This is how I understood XMPP messaging to work. That you can't send from A->B but it must be A#123 -> B#123.
However, my server seems to think otherwise. It continuously informs me of the following error:
2010.12.27 19:02:52 [org.jivesoftware.openfire.session.LocalOutgoingServerSession
.createOutgoingSession(LocalOutgoingServerSession.java:258)] Error trying to
connect to remote server: A(DNS lookup: A:5269)
java.net.UnknownHostException: A
In both A and B's roster on the Openfire server, they have each other as a contact with the proper JIDs (username#123).
Can anyone provide some insight? I'm lost.
Edit
I'm trying to use Wireshark to catch the XML sent to and from the Openfire server to determine if the recipient of the message is named properly (A#123 instead of A).
Upon using Wireshark, I received this as the XML being transferred:
\302\3469\223\341\3429\000\000\000\000\377\377
I have disabled SSL, I have connected un-securely. I'm not sure why I'm getting SSL type XML, is that what it is?
Turns out the answer to this problem was something that was just overlooked.
In the first line of code:
chat = chatmanager.createChat(username, new MessageListener() {
public void processMessage(Chat chat, Message message) {}
});
I didn't make the variable "username" have the proper IP extension. So it was merely "A" instead of "A#123"
Moving "sendUsername" to the top and Changing "username" to "sendUsername" makes everything work great :)
Silly mistake.
Using IP addresses is almost always more confusing than you think it is.
There's a good chance you have OpenFire misconfigured, so that the IP address isn't a valid hostname. Go into the admin console, under "System Properties", and make sure that the xmpp.domain property is set to your IP address.