I'll try to be brief.
I wish to create communication between 2 java apps (that will later be transported to android) without passing through a server. As such, I have spent weeks looking around, and after a lot of work I found stun and ice4j. The best explanation of how to use ice4j I found here, and it pretty much showed me what I need to do to add stun servers to an agent (I don't really know what an agent is, just that it manages my communications with STUN and TURN), through this code:
import java.io.IOException;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.ice4j.Transport;
import org.ice4j.TransportAddress;
import org.ice4j.ice.Agent;
import org.ice4j.ice.IceMediaStream;
import org.ice4j.ice.harvest.StunCandidateHarvester;
public class ice4jTesting {
public static void main(String[] args) {
Agent agent = new Agent();
String[] hostnames = new String[] {"jitsi.org", "numb.viagenie.ca", "stun.ekiga.net"};
for(String hostname: hostnames) {
try {
TransportAddress address;
address = new TransportAddress(InetAddress.getByName(hostname), 3478, Transport.UDP);
agent.addCandidateHarvester(new StunCandidateHarvester(address));
} catch (UnknownHostException ex) {
Logger.getLogger(SimpleStun.class.getName()).log(Level.SEVERE, null, ex);
}
}
IceMediaStream stream = agent.createMediaStream("audio");
int port = 5000;
try {
agent.createComponent(stream, Transport.UDP, port, port, port+100);
// The three last arguments are: preferredPort, minPort, maxPort
} catch (IllegalArgumentException | IOException ex) {
Logger.getLogger(SimpleStun.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
however, after this the tutorial utilizes SDPUtils, a class that is in the source code of ice4j I found on github, to recieve the SDP information from the agent. However I got ice4j.jar from the central maven repository, and added it to my netbeans regular project (I did this because I am not very familiar with maven, and just wanted a regular library on my regular project). This jar library does not have the SDPUtils class, and since I don't really understand enough of this code to fix it myself, I was wondering if any of you could help me either fix the code above, or show me an example of how to answer the question on the title.
However, unless you can either do what I said in the last sentence, or point me to some sample code, your help will most likely not be useful, since I am mentally incapable of understanding the theory behind this completely because of the many concepts I do not know.
I have until the end of this week to figure this out, and if I don't I'm pretty screwed. So please, if you can or know someone that can help, I would extremely appreciate it.
Thanks for reading it so far and trying to help :)
There you go
SdpUtils.java
Actually i'm also working on the same as my University project. From last week i'm digging web for p2p connection establish over nat.
I know that form where you got above Code snipet, i would like to inform you that there is errors in that code Here is the one that i corrected
import java.io.IOException;
import java.net.BindException;
import java.net.InetAddress;
import org.ice4j.Transport;
import org.ice4j.TransportAddress;
import org.ice4j.ice.Agent;
import org.ice4j.ice.IceMediaStream;
import org.ice4j.ice.harvest.StunCandidateHarvester;
public class IceTest {
public static void main(String[] args) throws Exception {
Agent agent = new Agent(); // A simple ICE Agent
/*** Setup the STUN servers: ***/
String[] hostnames = new String[] { "jitsi.org", "numb.viagenie.ca", "stun.ekiga.net" };
// Look online for actively working public STUN Servers. You can find
// free servers.
// Now add these URLS as Stun Servers with standard 3478 port for STUN
// servrs.
for (String hostname : hostnames) {
try {
// InetAddress qualifies a url to an IP Address, if you have an
// error here, make sure the url is reachable and correct
TransportAddress ta = new TransportAddress(InetAddress.getByName(hostname), 3478, Transport.UDP);
// Currently Ice4J only supports UDP and will throw an Error
// otherwise
agent.addCandidateHarvester(new StunCandidateHarvester(ta));
} catch (Exception e) {
e.printStackTrace();
}
}
/*
* Now you have your Agent setup. The agent will now be able to know its
* IP Address and Port once you attempt to connect. You do need to setup
* Streams on the Agent to open a flow of information on a specific
* port.
*/
IceMediaStream stream = agent.createMediaStream("audio");
int port = 5000; // Choose any port
try {
agent.createComponent(stream, Transport.UDP, port, port, port + 100);
// The three last arguments are: preferredPort, minPort, maxPort
} catch (BindException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
/*
* Now we have our port and we have our stream to allow for information
* to flow. The issue is that once we have all the information we need
* each computer to get the remote computer's information. Of course how
* do you get that information if you can't connect? There might be a
* few ways, but the easiest with just ICE4J is to POST the information
* to your public sever and retrieve the information. I even use a
* simple PHP server I wrote to store and spit out information.
*/
String toSend = null;
try {
toSend = SdpUtils.createSDPDescription(agent);
// Each computersends this information
// This information describes all the possible IP addresses and
// ports
} catch (Throwable e) {
e.printStackTrace();
}
/*The String "toSend" should be sent to a server. You need to write a PHP, Java or any server.
* It should be able to have this String posted to a database.
* Each program checks to see if another program is requesting a call.
* If it is, they can both post this "toSend" information and then read eachother's "toSend" SDP string.
* After you get this information about the remote computer do the following for ice4j to build the connection:*/
String remoteReceived = ""; // This information was grabbed from the server, and shouldn't be empty.
SdpUtils.parseSDP(agent, remoteReceived); // This will add the remote information to the agent.
//Hopefully now your Agent is totally setup. Now we need to start the connections:
agent.addStateChangeListener(new StateListener()); // We will define this class soon
// You need to listen for state change so that once connected you can then use the socket.
agent.startConnectivityEstablishment(); // This will do all the work for you to connect
}
}
This code Requires SIP server to be setup and the one on ice4j test is saying something else just have a look at Ice.java
Related
While performing a client-server communication with various forums, I am unable to perform Remote-object's lookup on the client machine.
The errors which I receive are ConnectIOException(NoRouteToHostException), and sometimes ConnectException and sometimes someother.
This is not what I want to ask. But, the main concern is how should I setup client platform and server platform --- talking about networking details --- this is what I doubt interferes with my connection.
My questions :-
How should I edit my /etc/hosts file on both client-side and server-side? Server's IP- 192.168.1.8 & Client's IP-192.168.1.100. Means, should I add the system name in both the files:
192.168.1.8 SERVER-1 # on the server side
192.168.1.100 CLIENT-1 # on the client side
Should I edit like this? Can this be one of the possible concerns? I just want to remove any doubts left over to perform the rmi-communication!
Also, I am also setting Server's hostname property using System.setProperty("java.rmi.server.hostname",192.168.1.8); on the server side. Should I do the same on the client-side too?
I've read about setting classpath while running the java program on both server-side as well as the client-side. I did this too,but,again the same exceptions. No difference at all. I've read that since Java update 6u45, classpaths aren't necessary to include! Please throw some light on this too...
If I am missing something, Please enlighten about the same too. A brief idea/link to resources are most preferred.
You don't need any of this unless you have a problem. The most usual problem is the one described in the RMI FAQ #A.1, and editing the hosts file of the server or setting java.rmi.server.hostname in the server JVM is the solution to that.
'No route to host' is a network connectivity problem, not an RMI problem, and not one you'll solve with code or system property settings.
Setting the classpath has nothing to do with network problems.
Here is server example of which transfers an concrete class. This class must be exist in server and client classpath with same structure
Message:
public class MyMessage implements Serializable {
private static final long serialVersionUID = -696658756914311143L;
public String Title;
public String Body;
public MyMessage(String strTitle) {
Title = strTitle;
Body = "";
}
public MyMessage() {
Title = "";
Body = "";
}
}
And here is the server code that gets an message and returns another message:
public class SimpleServer {
public String ServerName;
ServerRemoteObject mRemoteObject;
public SimpleServer(String pServerName) {
ServerName = pServerName;
}
public void bindYourself() {
try {
mRemoteObject = new ServerRemoteObject(this);
java.rmi.registry.Registry iRegistry = LocateRegistry.getRegistry(RegistryContstants.RMIPort);
iRegistry.rebind(RegistryContstants.CMName, mRemoteObject);
} catch (Exception e) {
e.printStackTrace();
mRemoteObject = null;
}
}
public MyMessage handleEvent(MyMessage mMessage) {
MyMessage iMessage = new MyMessage();
iMessage.Body = "Response body";
iMessage.Title = "Response title";
return iMessage;
}
public static void main(String[] server) {
SimpleServer iServer = new SimpleServer("SERVER1");
iServer.bindYourself();
while (true) {
try {
Thread.sleep(10000);
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
and here is the remote interface of server remote object:
public interface ISimpleServer extends java.rmi.Remote{
public MyMessage doaction(MyMessage message) throws java.rmi.RemoteException;
}
all you need is adding MyMessage class both in server and client classpath.
I am trying to connect with a Biometric Fingerprint Attendance Device using a Java program. The device I am using is a Biocom Fingerprint attendance system. However, I am search and reading about that and I see the SDK could used which based on device type (which hard, not logical, moreover, it is not global solution!)
I research for a global standard on how to connect, send and retrieve data with a Fingerprint Device which again I wasn't lucky enough to find a clear solution. Currently, I tried to connect with the device by creating a Socket object (through Ethernet port) but also not executed with me. This open infinite loop problems on my head.
Is there any general, standard way to connect, send and retrieve data from such device using Java?
Can a Socket be considered as a solution for such problem?
If yes, what is wrong in my code below? What additional things more than the host IP and port number are needed to connect with the device?
The Socket code that used:
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.Socket;
import java.net.UnknownHostException;
public class Requester {
Socket requestSocket;
ObjectOutputStream out;
ObjectInputStream in;
String message;
Requester() {
}
void run() throws IOException {
try {
// 1. creating a socket to connect to the server
requestSocket = new Socket("192.168.0.19", 4370);
System.out.println("Connected to given host in port 4370");
// 2. get Input and Output streams
in = new ObjectInputStream(requestSocket.getInputStream());
// 3: Communicating with the server
String line;
while (true) {
line = in.readLine();
if (line != null) {
System.out.println(line);
}
}
} catch (UnknownHostException unknownHost) {
System.err.println("You are trying to connect to an unknown host!");
} catch (IOException ioException) {
ioException.printStackTrace();
} catch (Exception Exception) {
Exception.printStackTrace();
} finally {
in.close();
requestSocket.close();
}
}
void sendMessage(String msg) {
try {
out.writeObject(msg);
out.flush();
System.out.println("client: " + msg);
} catch (IOException ioException) {
ioException.printStackTrace();
}
}
public static void main(String args[]) throws IOException {
Requester client = new Requester();
client.run();
}
}
This image may give more details:
You don't need the ObjectInputStream. Just use the InputStream you get from requestSocket.getInputStream().
Alternatively use a terminal programm like putty to connect to your device. This requires no coding.
Biocom Biometrics are ZKTeco devices. ZkTeco devices are launched only with windows SDK. You can download the SDK from https://www.zkteco.com/en/download_catgory.html and use the DLL in java which can run only on Windows platorm. For HTTP communication, to work in any platform through any language, refer http://camsunit.com/application/zk-teco-essl-api-integration.html
I'm trying to make a Java interface to send some AT commands to a GPRS Module.
I already had a working interface on Processing, but I migrated to pure Java because I find it easier to make graphic interfaces.
The Processing program sends data over serial to COM#. COM# is an Arduino with a GPRS Shield. All the Arduino Code does is pass the data received to the GPRS module and viceversa:
void loop(){
if (GPRS.available())
{
while(GPRS.available())
{
buffer[count++]=GPRS.read();
if(count == 64)break;
}
Serial.write(buffer,count);
clearBufferArray();
count = 0;
}
if (Serial.available()){
delay(100);
while(Serial.available()){
GPRS.write(Serial.read());
}
}
}
So I know that works fine because I've tested it using the Processing interface, and an external tool called SSCOM and all the comands are interpreted correctly.
Now the problem is, that when I tried to make the interface on java, using RXTX, it's not working at all. I'm not getting any errors on the console, and the only data I'm receiving on the Arduino is ΓΏ (char 255) each time I run java, and it's being sent when opening the port, not when writing to the serial port.
Here's the SerialHandlerclass I'm using. I found it around the web.
import gnu.io.CommPortIdentifier;
import gnu.io.NoSuchPortException;
import gnu.io.PortInUseException;
import gnu.io.SerialPort;
import gnu.io.UnsupportedCommOperationException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
public class SerialPortHandler {
private SerialPort serialPort;
private OutputStream outStream;
private InputStream inStream;
public void connect(String portName) throws IOException, PortInUseException, NoSuchPortException {
try {
// Obtain a CommPortIdentifier object for the port you want to open
CommPortIdentifier portId =
CommPortIdentifier.getPortIdentifier(portName);
// Get the port's ownership
serialPort =
(SerialPort) portId.open("Demo application", 5000);
// Set the parameters of the connection.
setSerialPortParameters();
// Open the input and output streams for the connection. If they won't
// open, close the port before throwing an exception.
outStream = serialPort.getOutputStream();
inStream = serialPort.getInputStream();
} catch (NoSuchPortException e) {
throw new IOException(e.getMessage());
} catch (PortInUseException e) {
throw new IOException(e.getMessage());
} catch (IOException e) {
serialPort.close();
throw e;
}
}
/**
* Get the serial port input stream
* #return The serial port input stream
*/
public InputStream getSerialInputStream() {
return inStream;
}
/**
* Get the serial port output stream
* #return The serial port output stream
*/
public OutputStream getSerialOutputStream() {
return outStream;
}
/**
* Sets the serial port parameters
*/
private void setSerialPortParameters() throws IOException {
int baudRate = 19200;
try {
serialPort.setSerialPortParams(
baudRate,
SerialPort.DATABITS_8,
SerialPort.STOPBITS_1,
SerialPort.PARITY_NONE);
serialPort.setFlowControlMode(
SerialPort.FLOWCONTROL_NONE);
} catch (UnsupportedCommOperationException ex) {
throw new IOException("Unsupported serial port parameter");
}
}
}
And here's my main class:
public class Main {
SerialPortHandler serial = new SerialPortHandler();
serial.connect("COM3");
OutputStream serialOut = serial.getSerialOutputStream();
String s = "AT+CPOWD=0\r\n";
serialOut.write(s.getBytes());
serialOut.flush();
}
}
rxtxSerial.dll and RXTXcomm.jar are in jre\bin and jre\lib\ext respectively.
I can't find the problem, like I said, I don't get any errors or warnings anywhere.
I'm using NetBeans 7.3.1, JDK 1.7 and Windows 8.1 x64.
I also tried using jSSC but I get the same results.
I solved the problem. It wasn't the jSSC or RXTX library.
PeterMmm was right, I needed a delay, but I needed it on my java program.
When I was testing communication, I was opening the port and sending data right away. The problem is Arduino by default resets when a connection is established, so the Arduino wasn't ready to process it.
A couple days ago, I decided to try again, with jSSC, but this time, the java program asked for an input to send through the serial port, leaving time for Arduino to boot. Arduino successfully received anything I typed.
Now that I implemented serial communication on the user interface I was developing, everything runs smoothly.
In java RMI i am building a chat application. But i am not able to figure out a way to find out, whether the IP which is hitting my server is from my internal organization network(INTRANET) or from external world(INTERNET).
Right now i am using
try {
System.setProperty("java.rmi.server.hostname",InetAddress.getLocalHost().getHostAddress());
Registry statusRegistry = LocateRegistry.createRegistry(ChatConstants.statusPort);
ChatInterface chat = new ChatImpl(ChatConstants.statusPort) ;
statusRegistry.rebind("statusconnection",chat);
System.out.println("RMIStatusConnection Server is started...");
} catch (RemoteException e) {
System.out.println("RMIStatusConnection failed...");
e.printStackTrace();
} catch (UnknownHostException e) {
e.printStackTrace();
}
Try RemoteServer.getClientHost(), but it may only provide the address of the nearest NAT device.
NB there's not much point in setting java.rmi.server.hostname like that. That's the default. You only need to set it if there's something wrong with the default setting.
Using JXTA 2.6 from http://jxse.kenai.com/ I want to create application that can run multiple peers on one or more hosts. The peers should be able to find each other in a group and send direct messages as well as propagate messages.
What would a simple hello world type of application look like that meet these requirements?
I created this question with the intention of supplying a tutorial like answer, an answer I tried very hard to find two months ago when starting to look at JXTA for a uni project. Feel free to add your own answers or improve on mine. I will wait a few days and accept the best one.
Introduction to JXTA 2.6 Peer discovery and pipe messaging
The guide I wish I had 2 months ago =)
After spending a lot of time during a university course building
a JXTA p2p application I feel a lot of the frustrations and
confusion I went through could have been avoided with a good
starting point.
The jar files you will need can be found here:
https://oss.sonatype.org/content/repositories/comkenaijxse-057/com/kenai/jxse/jxse/2.6/jxse-2.6.jar
http://sourceforge.net/projects/practicaljxta/files/lib-dependencies-2.6.zip/download
Throw them into Yourproject/lib, open up eclipse, create a new project "Yourproject" and it should sort out
importing the libraries for you.
You will soon come to realize that almost any information on the web is out dated, very out dated.
You will also run into a lot of very confusing error messages and most of them can be avoided by
going through this check list.
Is your firewall turned off or at least open for the ports you use?
You can disable iptables using "sudo service iptables stop" under Fedora.
Check spelling! Many times when joining groups or trying to send messages spelling the group name wrong or not using the
exact same advertisement when looking for peers and services or opening pipes will cause very confusing messages.
Was trying to figure out why my pipe connections timed out when I spotted the group names being "Net info" and "Net_info".
Are you using a JXTA home directory? One per each peer you run on the same computer?
Do you really use a unique peer id? The seed provided to IDFactory need to be long enough or else you will get duplicates.
Turn off SELinux. I have had SELinux turned off during the development but can imagine it causing errors.
While it is common to group all fields together I introduce them as I go to show where they are needed.
Note: This will not work in 2.7. Some issue with PSE membership I think.
public class Hello implements DiscoveryListener, PipeMsgListener {
// When developing you should handle these exceptions, I don't to lessen the clutter of start()
public static void main(String[] args) throws PeerGroupException, IOException {
// JXTA logs a lot, you can configure it setting level here
Logger.getLogger("net.jxta").setLevel(Level.ALL);
// Randomize a port to use with a number over 1000 (for non root on unix)
// JXTA uses TCP for incoming connections which will conflict if more than
// one Hello runs at the same time on one computer.
int port = 9000 + new Random().nextInt(100);
Hello hello = new Hello(port);
hello.start();
hello.fetch_advertisements();
}
private String peer_name;
private PeerID peer_id;
private File conf;
private NetworkManager manager;
public Hello(int port) {
// Add a random number to make it easier to identify by name, will also make sure the ID is unique
peer_name = "Peer " + new Random().nextInt(1000000);
// This is what you will be looking for in Wireshark instead of an IP, hint: filter by "jxta"
peer_id = IDFactory.newPeerID(PeerGroupID.defaultNetPeerGroupID, peer_name.getBytes());
// Here the local peer cache will be saved, if you have multiple peers this must be unique
conf = new File("." + System.getProperty("file.separator") + peer_name);
// Most documentation you will find use a deprecated network manager setup, use this one instead
// ADHOC is usually a good starting point, other alternatives include Edge and Rendezvous
try {
manager = new NetworkManager(
NetworkManager.ConfigMode.ADHOC,
peer_name, conf.toURI());
}
catch (IOException e) {
// Will be thrown if you specify an invalid directory in conf
e.printStackTrace();
}
NetworkConfigurator configurator;
try {
// Settings Configuration
configurator = manager.getConfigurator();
configurator.setTcpPort(port);
configurator.setTcpEnabled(true);
configurator.setTcpIncoming(true);
configurator.setTcpOutgoing(true);
configurator.setUseMulticast(true);
configurator.setPeerID(peer_id);
}
catch (IOException e) {
// Never caught this one but let me know if you do =)
e.printStackTrace();
}
}
private static final String subgroup_name = "Make sure this is spelled the same everywhere";
private static final String subgroup_desc = "...";
private static final PeerGroupID subgroup_id = IDFactory.newPeerGroupID(PeerGroupID.defaultNetPeerGroupID, subgroup_name.getBytes());
private static final String unicast_name = "This must be spelled the same too";
private static final String multicast_name = "Or else you will get the wrong PipeID";
private static final String service_name = "And dont forget it like i did a million times";
private PeerGroup subgroup;
private PipeService pipe_service;
private PipeID unicast_id;
private PipeID multicast_id;
private PipeID service_id;
private DiscoveryService discovery;
private ModuleSpecAdvertisement mdadv;
public void start() throws PeerGroupException, IOException {
// Launch the missiles, if you have logging on and see no exceptions
// after this is ran, then you probably have at least the jars setup correctly.
PeerGroup net_group = manager.startNetwork();
// Connect to our subgroup (all groups are subgroups of Netgroup)
// If the group does not exist, it will be automatically created
// Note this is suggested deprecated, not sure what the better way is
ModuleImplAdvertisement mAdv = null;
try {
mAdv = net_group.getAllPurposePeerGroupImplAdvertisement();
} catch (Exception ex) {
System.err.println(ex.toString());
}
subgroup = net_group.newGroup(subgroup_id, mAdv, subgroup_name, subgroup_desc);
// A simple check to see if connecting to the group worked
if (Module.START_OK != subgroup.startApp(new String[0]))
System.err.println("Cannot start child peergroup");
// We will spice things up to a more interesting level by sending unicast and multicast messages
// In order to be able to do that we will create to listeners that will listen for
// unicast and multicast advertisements respectively. All messages will be handled by Hello in the
// pipeMsgEvent method.
unicast_id = IDFactory.newPipeID(subgroup.getPeerGroupID(), unicast_name.getBytes());
multicast_id = IDFactory.newPipeID(subgroup.getPeerGroupID(), multicast_name.getBytes());
pipe_service = subgroup.getPipeService();
pipe_service.createInputPipe(get_advertisement(unicast_id, false), this);
pipe_service.createInputPipe(get_advertisement(multicast_id, true), this);
// In order to for other peers to find this one (and say hello) we will
// advertise a Hello Service.
discovery = subgroup.getDiscoveryService();
discovery.addDiscoveryListener(this);
ModuleClassAdvertisement mcadv = (ModuleClassAdvertisement)
AdvertisementFactory.newAdvertisement(ModuleClassAdvertisement.getAdvertisementType());
mcadv.setName("STACK-OVERFLOW:HELLO");
mcadv.setDescription("Tutorial example to use JXTA module advertisement Framework");
ModuleClassID mcID = IDFactory.newModuleClassID();
mcadv.setModuleClassID(mcID);
// Let the group know of this service "module" / collection
discovery.publish(mcadv);
discovery.remotePublish(mcadv);
mdadv = (ModuleSpecAdvertisement)
AdvertisementFactory.newAdvertisement(ModuleSpecAdvertisement.getAdvertisementType());
mdadv.setName("STACK-OVERFLOW:HELLO");
mdadv.setVersion("Version 1.0");
mdadv.setCreator("sun.com");
mdadv.setModuleSpecID(IDFactory.newModuleSpecID(mcID));
mdadv.setSpecURI("http://www.jxta.org/Ex1");
service_id = IDFactory.newPipeID(subgroup.getPeerGroupID(), service_name.getBytes());
PipeAdvertisement pipeadv = get_advertisement(service_id, false);
mdadv.setPipeAdvertisement(pipeadv);
// Let the group know of the service
discovery.publish(mdadv);
discovery.remotePublish(mdadv);
// Start listening for discovery events, received by the discoveryEvent method
pipe_service.createInputPipe(pipeadv, this);
}
private static PipeAdvertisement get_advertisement(PipeID id, boolean is_multicast) {
PipeAdvertisement adv = (PipeAdvertisement )AdvertisementFactory.
newAdvertisement(PipeAdvertisement.getAdvertisementType());
adv.setPipeID(id);
if (is_multicast)
adv.setType(PipeService.PropagateType);
else
adv.setType(PipeService.UnicastType);
adv.setName("This however");
adv.setDescription("does not really matter");
return adv;
}
#Override public void discoveryEvent(DiscoveryEvent event) {
// Found another peer! Let's say hello shall we!
// Reformatting to create a real peer id string
String found_peer_id = "urn:jxta:" + event.getSource().toString().substring(7);
send_to_peer("Hello", found_peer_id);
}
private void send_to_peer(String message, String found_peer_id) {
// This is where having the same ID is important or else we wont be
// able to open a pipe and send messages
PipeAdvertisement adv = get_advertisement(unicast_id, false);
// Send message to all peers in "ps", just one in our case
Set<PeerID> ps = new HashSet<PeerID>();
try {
ps.add((PeerID)IDFactory.fromURI(new URI(found_peer_id)));
}
catch (URISyntaxException e) {
// The JXTA peer ids need to be formatted as proper urns
e.printStackTrace();
}
// A pipe we can use to send messages with
OutputPipe sender = null;
try {
sender = pipe_service.createOutputPipe(adv, ps, 10000);
}
catch (IOException e) {
// Thrown if there was an error opening the connection, check firewall settings
e.printStackTrace();
}
Message msg = new Message();
MessageElement fromElem = null;
MessageElement msgElem = null;
try {
fromElem = new ByteArrayMessageElement("From", null, peer_id.toString().getBytes("ISO-8859-1"), null);
msgElem = new ByteArrayMessageElement("Msg", null, message.getBytes("ISO-8859-1"), null);
} catch (UnsupportedEncodingException e) {
// Yepp, you want to spell ISO-8859-1 correctly
e.printStackTrace();
}
msg.addMessageElement(fromElem);
msg.addMessageElement(msgElem);
try {
sender.send(msg);
} catch (IOException e) {
// Check, firewall, settings.
e.printStackTrace();
}
}
#Override public void pipeMsgEvent(PipeMsgEvent event) {
// Someone is sending us a message!
try {
Message msg = event.getMessage();
byte[] msgBytes = msg.getMessageElement("Msg").getBytes(true);
byte[] fromBytes = msg.getMessageElement("From").getBytes(true);
String from = new String(fromBytes);
String message = new String(msgBytes);
System.out.println(message + " says " + from);
}
catch (Exception e) {
// You will notice that JXTA is not very specific with exceptions...
e.printStackTrace();
}
}
/**
* We will not find anyone if we are not regularly looking
*/
private void fetch_advertisements() {
new Thread("fetch advertisements thread") {
public void run() {
while(true) {
discovery.getRemoteAdvertisements(null, DiscoveryService.ADV, "Name", "STACK-OVERFLOW:HELLO", 1, null);
try {
sleep(10000);
}
catch(InterruptedException e) {}
}
}
}.start();
}
}