Develop Reference

How to connect to a broker API using sockets and Java?

I've been trying to connect to the XTB API and I can't seem to make it work.
I have zero experience with sockets and I'm learning on the go. I'm trying to send the JSON object and I'm expecting some kind of response either a success message or an error but I don't get anything. I don't even know if I'm doing it right.
public static void main(String[] args) {
String host = "xapi.xtb.com";
int port = 5112;
Socket s;
try {
JSONObject main = new JSONObject();
JSONObject user = new JSONObject();
main.put("command", "login");
user.put("userId", "MY_ID");
user.put("password", "MY_PSSWD");
main.put("arguments", user);
s = new Socket(host, port);
SocketAddress a;
a = new InetSocketAddress("xapi.xtb.com", 5112);
BufferedReader in = new BufferedReader(new InputStreamReader(s.getInputStream()));
BufferedWriter out = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));
out.write(main.toString());
String response = in.readLine();
System.out.println(response);
in.close();
out.close();
} catch (IOException ex) {
ex.printStackTrace(System.out);
}
}

I only managed to get their WebSocket endpoints to work. That, in addition to the fact that their entire API documentation contains WebSocket commands only, makes me think they expect users to connect that way.
I can't help you with Java, but the algorithm is as follows:
1. Define connection
Get a WebSocket client library / package. Usually first thing you do is to instantiate an object using the wss://... address as parameter. Don't issue the connect command at this stage.
2. Define event handlers
Most WebSocket clients dispatch events which you need to handle in your code.
First event will typically be 'open' and it will be fired once the connection is established. Every message coming from server will fire a 'message' event. You need to write handlers for the 'onOpen' and 'onMessage' events (however the naming convention may be) which will execute your code's logic.
Typically there will be a 'send' command in your WebSocket package that you can use to send messages to the server. Use the command described in the documentation as payload of the send command:
// pseudocode
ws.send({
"command":"login",
"arguments": {
"userId":"1000",
"password":"PASSWORD"
}
})
3. Connect
Once the event handlers are defined, you can issue the 'connect' command.
Good luck with your trading. Hope it helps.

maybe im very, very, very too late but... I have been playing with your example.
You are getting null, because the connection is plain http.
To fix it, you need to change:
import java.net.Socket;
to
import javax.net.ssl.SSLSocket;
import javax.net.ssl.SSLSocketFactory;
And then, when creating the socket...
instead of
Socket s
s = new Socket(host, port);
You must put this:
SSLSocketFactory factory = (SSLSocketFactory) SSLSocketFactory.getDefault();
SSLSocket s = (SSLSocket) factory.createSocket(host, port);
Also, after out.write.... add
out.flush();
And you are done
Why? in the xtb api docs they said this:
All servers use SSL connection.
And after messing a bit with wireshark, I found that the JSON was sent in plain text...
You may have already found it before, because this question is old, but it remains here in case someone else has the problem

Smack send and receive message without chat

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.

Converting JMS Message to IBM PCF

I am in a bit of a bind. I am trying to read a message of a WMQ via jms and then convert it to a pcf message for processing. I have only been able to find one resource on this and it hasn't been very helpful [bottom of http://www-01.ibm.com/support/docview.wss?uid=swg21395682 ]
I have tried to implement the technique in the above doc but every time I get to line
PCFMessage response = new PCFMessage(dataInput);
I throw MQRC 3013 - MQRCCF_STRUCTURE_TYPE_ERROR
This is the way my code looks, maybe you can see something I don't.
BytesMessage message = null;
do {
// The consumer will wait 10 seconds (10,000 milliseconds)
message = (BytesMessage) myConsumer.receive(10000);
// get the size of the bytes message & read into an array
int bodySize = (int) message.getBodyLength();
byte[] data = new byte[bodySize];
message.readBytes(data, bodySize);
// Read into Stream and DataInput Stream
ByteArrayInputStream bais = new ByteArrayInputStream(data);
DataInput dataInput = new DataInputStream(bais);
// Pass to PCF Message to process
//MQException.logExclude(new Integer(2079));
PCFMessage qStatsPcf = new PCFMessage(dataInput);
session.commit();
if (message != null) {
processMessage(qStatsPcf);
}
} while (message != null);
myConsumer.close();
A couple updates in response to T.Rob's answer.
I am currently running MQ 7.0. This is a what it is type thing, I can't currently upgrade.
As to what I am trying to do, I am pulling messages from SYSTEM.ADMIN.STATISTICS.QUEUE and I want to parse that information for auditing purposes. The reasoning behind converting to a PCF message is that I am looking to pull some PCF parameters from these messages - for example .getParameter(PCFConstants.MQIAMO_PUTS)
I am not attempting to send messages to MQ in anyway, just pull messages off and process them.

A couple problems with this question:
There is no mention of the version of the version of MQ jms client that is in use. Since IBM has repackaged the Java/JMS classes several times, it is necessary to mention which version you are working with to get a better answer.
It is unclear what it is you are trying to do. An MQ PCF message is processed by the MQ Command Server. The messages are a binary format consisting of a linked list of name/type/value tuples. If your message body is not already in PCF name/type/value format, then casting it as a PCF message is expected to fail.
Since it is not possible to respond to the question as worded with a solution, I'll provide some recommendations based on wild guesses as to what it is you might be trying to do.
Use a modern MQ client. The Technote you linked to is for out-of-support versions of MQ client. You want one that is at least MQ v7.1, but preferably v8.0. since any version of MQ client works with any version of MQ, use the version that is most current. Just remember, the functionality you get is based on the oldest version of MQ used at the client or server. A v8.0 client doesn't get you v8.0 function on a v7.0 QMgr. Go to the SupportPacs page and look for entries with names like MQC**. The MQ v8.0 client is current and it is SupportPac MQC8.
If you really are trying to submit PCF messages to MQ's command processor, instantiate a PCF Agent to do it. Then construct the PCF message using one of the PCF message constructors that lets you specify the selectors and their values.
What happened when you tried using the PCF Java samples? Did they also fail? Did they work? If so, how does your code differ? You did look at IBM's PCF samples, right? Please see Installation directories for samples for the location for the sample programs, including the PCF samples.
If you are not attempting to send messages to the MQ Command Processor, please update the question to let us know what it is you are trying to do and why you believe you need PCF messages to do it.

my 2 cents...
Why are you using JMS to retrieve PCF Messages?
MQ Java is best placed to handle all statistics and event message. My suggestion is go with MQQueueManager object and retrieve a MQMessage out of SYSTEM.ADMIN.STATISTICS.QUEUE and pass it to PCFMessage constructor.
I have not compiled or tested the following, but it gives an outline.
//no try catch block to keep it simple
//assumed MQQueueManager (qmgr object) is already created
//assumed statQueue is available through qmgr.accessQueue() method
do {
MQMessage message = new MQMessage();
//gmo as CMQC.MQGMO_FAIL_IF_QUIESCING | CMQC.MQGMO_WAIT | CMQC.MQGMO_SYNCPOINT | CMQC.MQGMO_CONVERT;
message = statQueue.get(message, gmo);
// Pass to PCF Message to process
PCFMessage qStatsPcf = new PCFMessage(message);
qmgr.commit();
if (message != null) {
processMessage(qStatsPcf);
}
} while (message != null);
statQueue.close();
qmgr.close();

Designing java client

I'm currently developing a client/server application in Java and i can't make up my mind on how to design the client.
At the moment i have a server that can accept multiple connections and every connection has a loop listening for commands and respond to them. The server looks like this:
try{
mIn = new DataInputStream(mSocket.getInputStream());
mOut = new DataOutputStream(mSocket.getOutputStream());
while(true){
byte tPackType = mIn.readByte();
switch(tPackType){
case PackType.LOGIN:
login();
break;
case PackType.REGISTER:
register();
break;
default:
}
}
}catch (IOException e){
mLog.logp(Level.WARNING, this.getClass().getName(), "run()", "IOException in run()", e);
}finally{
try{
mOut.close();
mIn.close();
mSocket.close();
}catch (IOException e){
e.printStackTrace();
}
}
Now, the client is basically just a number of methods sending a request to the server and returns the response. I want to be able to receive updates from the server.
I would appreciate any suggestions on reading that can help me find a solution.
Is there any patterns i could look into?
Thank you in advance, veLr.

I want to be able to receive updates from the server
I think that you have two options to do this.
Option 1 is to make your client poll the server for updates. I would not recommend this since this will eventually increase your load on your server. You will most likely have performance issue the moment you attempt to scale your system up.
Option 2 is to create a small server on your client. So basically, whenever there is an update, the server would connect to the client and send it the updates. I would recommend this procedure since it allows you to establish connections between your server and clients only when needed. The problem, when opposed to the previous method, is that you will need to track of the ports and IP's of your clients. You could implement a HashTable with Client ID's as keys and their connection properties as their keys. Once you have an update, you will look up the client in the HashTable, obtain the connection information, connect and send the information.
The server on the client side will then get the data and do whatever you want the client to do once an update is received.

Java websocket host?

I'm trying some multiplayer game ideas out at the moment and am trying to create a Java application to serve a web browser based multiplayer game.
My development environment is Eclipse on the main machine, and notepad + Google Chrome on this laptop.
I'm creating the websocket using javascript at the client end, and using the java.net.Socket at the server end.
I've managed to get a connection acknowledged at both ends, but can't seem to send or recieve any data between them without the client closing the connection (doesn't even error; just seems to freak out at something and call socket.close).
Does anyone have any ideas?
Here's some code:
Client:
<script type="text/javascript">
var socket;
function init() {
socket = new WebSocket("ws://192.168.0.3:10000");
socket.onopen = function() { alert('OPEN: ' + socket.readyState); }
socket.onmessage = function (msg) { alert('DATA: ' + msg.data); }
socket.onerror = function (msg) { alert('DATA: ' + msg.data); }
socket.onclose = function () { alert('CLOSED: ' + socket.readyState); }
}
function onClick() {
socket.send("YAY!");
}
</script>
Server:
public static void main(String args[])
{
System.out.printLn("Websocket server test");
ServerSocket connectSocket = null;
try
{
Socket clientSocket;
connectSocket = new ServerSocket(10000);
System.out.printLn("Waiting for connection...");
clientSocket = connectSocket.accept();
System.out.printLn("Got one!");
PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);
BufferedReader in = new BufferedReader(
new InputStreamReader(clientSocket.getInputStream()));
for(int i=0;i<100;i++) //Shit but easy
{
String data = in.readLine();
System.out.printLn("Got data: " + data);
out.printLn("YAY!");
}
}
catch (IOException e)
{
System.out.printLn("You fail: " + e.getMessage());
}
System.out.printLn("Finished!");
}

Rather than going the painful way of implementing the spec in Java, I'd suggest that you use an existing solution like jWebSocket.
Also if you don't mind leaving Java land, I'd also suggest that you take a look at Node.js for your Server.
Doing both Server and Client in JavaScript will save you lots of time and lots of Code, especially since JSON just doesn't fit that well into static land. Also creating multiplayer servers in Node.js is trivial, since the event based, single threaded model fits the whole thing pretty well.
More information on WebSocket can be found in the FAQ. In case you want to get started with Node.js take a look at the TagWiki.
shameless plug follows
For two multiplayer games that were written using Node.js take a look at my GitHub page.

Try this lib - https://github.com/mrniko/netty-socketio
Based on high performance socket lib Netty. It supports latest protocol of Socket.IO server. Several transports including websocket.
On web side use Socket.IO client javascript lib:
<script type="text/javascript">
var socket = io.connect('http://localhost:81', {
'transports' : [ 'websocket' ],
'reconnection delay' : 2000,
'force new connection' : true
});
socket.on('message', function(data) {
// here is your handler on messages from server
});
// send object to server
var obj = ...
socket.json.send(obj);
</script>

I would suggest our high level solution: Bristleback Server. It contains both server and client, you can choose from several existing low level WebSocket engines (like Jetty, Netty or Tomcat), developing with Bristleback is extremally fast and easy. However, it is still Beta and we are working hard to release a final 1.0.0 version. If you use Maven, we have provided an archetype with ready to use web application.
I am one of the co-creators of Bristleback Server.

As no one yet really answered your question: the reason it does not work, is because you are not implementing the websocket specification. It takes of lot more work to setup a proper websocket connection than just opening a socket, as the websocket connection setup starts with a HTTP upgrade request. Your client is closing the connection, because it does not receive a positive answer on the upgrade request to start with.

I can't help you with sockets, but can i suggest you to use RMI technology? I'm trying to make a multiplayer rpg in java, and i'm using remote method invocation between server and client (it is possible also call-back the client from the server). It's really easy use it, but it uses TCP instead of UDP. In LAN experience there is no lag, on internet I have not tried yet. However, if your game tolerates just a bit retard between request and response, there is no problem.
This is the link of my project, Client and Server classes may be useful for you.