Sockets and net communication

I got a project for school and i decided to program an net checkers game.
I've looked up tutorial and found out some stuff on sockets but dont really understand how to send data from one computer to another.
I need to send a string from one computer in the network to another, can anyone direct me to some source code or tutorial which will help me with this, or just help me in any way.

What do you mean when you say client to client sockets? P2Pparhapse?
I believe there is no such thing as client to client sockets... You'll need to create P2P architecture on your own if that is what you need...

Similar Messages

Sockets and thread communication multiplexing?

Hello,
I need to implement a server which will have a maximum of 10 clients connected.
I wanted to go for classic blocking I/O because I won't have much clients.
My problem is that even if I accept() some sockets and then create a thread for each socket,
then I still need to communicate some data to the other threads, problem is that I am blocked
on the read() operation, how could I address this problem?
I mean, lets say I am thread1 and blocked on read() on my socket, now thread7 wants to tell
me something like a chat message coming from client he handles, how could thread7 manage
to wake thread1 and send him a message somehow?
I do not want to deal with NIO stuff if possible because I do not need to scale, I just have a
problem because I am stuck on the read.
I will run on Windows.
Thanks for help.
Edited by: Marzullo on Jul 15, 2010 1:05 PM

Fully answered in [your other thread|http://forums.sun.com/thread.jspa?threadID=5445070&messageID=11020688#11020688].
Please don't multipost, as it can lead to people wasting their time repeating others' answers.

Conflict between socket and RMI

Hi
I wrote a program in client-server using socket and it was fine. I also wrote a client-server program using RMI. Fine as well. But after I connected the client-server using socket (open socket, send-receive messages, close socket), then use RMI. I got java.rmi.NotBoundException.
Would anyone have a look and provide your feedback please? Thanks.
big J
*****************this is Server.java ***************************
package single;
import java.io.*;
import java.rmi.Naming;
import java.rmi.RemoteException;
import java.net.*;
import java.rmi.*;
public class Server
extends Thread {
public static final int SOCKETPORT = 5555;
private String serverName;
public Server() throws IOException {
System.out.println("*** socket opened ***");
serverName = new String("localhost");
ServerSocket serverSocket = new ServerSocket(SOCKETPORT);
Socket socket = serverSocket.accept();
InputStream is = socket.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(is));
System.out.println(bufferedReader.readLine());
OutputStream os = socket.getOutputStream();
PrintWriter printWriter = new PrintWriter(new OutputStreamWriter(os), true);
printWriter.println("from server");
os.close();
is.close();
socket.close();
System.out.println("*** socket closed ***");
public void runServer() {
System.out.println("*** start of run():RMI ***");
System.setSecurityManager(new SecurityManager());
try {
RMIInterfaceImpl rMIInterfaceImpl = new RMIInterfaceImpl();
Naming.bind("//" + serverName + ":9999/RMIInterface", rMIInterfaceImpl);
catch (RemoteException ex) {
catch (MalformedURLException ex) {
catch (AlreadyBoundException ex) {
System.out.println("*** end of run():RMI ***");
public static void main(String args[]) throws Exception {
Server server = new Server();
server.runServer();
******************this is Client.java **************************
package single;
import java.io.*;
import java.net.*;
import java.rmi.Naming;
public class Client {
private String serverName;
private final static int SOCKETPORT = 5555;
public Client() throws IOException {
serverName = new String("localhost");
Socket socket = new Socket(serverName, SOCKETPORT);
OutputStream os = socket.getOutputStream();
PrintWriter printWriter=new PrintWriter(os, true);
printWriter.println("from client");
InputStream is = socket.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(is));
System.out.println(bufferedReader.readLine());
is.close();
os.close();
socket.close();
public void runClient() throws Exception {
System.out.println("*** start of runClient():RMI ***");
System.setSecurityManager(new SecurityManager());
RMIInterface rMIInterfaceImpl = (RMIInterface) Naming.lookup(
"//" + serverName + ":9999/RMIInterface");
String str = rMIInterfaceImpl.print();
System.out.println(str);
rMIInterfaceImpl.serverSide();
System.out.println("*** end of runClient():RMI ***");
public static void main(String args[]) throws Exception {
Client client = new Client();
client.runClient();
***************** this is RMIInterface.java ***********************
package single;
import java.rmi.Remote;
import java.rmi.RemoteException;
interface RMIInterface
extends Remote {
String print() throws RemoteException;
void serverSide() throws RemoteException;
********************* this is RMIInterfaceImpl.java ***************
package single;
import java.rmi.RemoteException;
import java.rmi.server.UnicastRemoteObject;
public class RMIInterfaceImpl
extends UnicastRemoteObject
implements RMIInterface {
public RMIInterfaceImpl() throws RemoteException {}
public String print() {
return new String("hello world");
public void serverSide(){
System.out.println("this should appear in serverside");

I think you have a timing problem between your client and server. As soon as your client and server programs have finished their socket communication, they will both do their "runServer"/"runClient" methods. If the client attempts to lookup the server before the server has registered itself via Naming.bind(), I would expect that's why you're getting a NotBoundException in the client.
You probably wouldn't use the design of your test client/server for something significant, but a quick and dirty way to make this work might be to have the client call Thread.sleep() for a few seconds before trying to do the lookup.

Socket and Security Policy

I've tried to set experiment with Socket communication in Flex, but I keep hitting problems. Approach 1: in a Flex web app, I load a crossdomain security policy from a server. I then open a socket and write a few bytes to the server. In my server, I do not get the expected output on the stream--in fact, I get nothing at all--until I close the Flex application, at which point I get a seemingly inifinite stream of the bytes '0xEFBFBF'. Here's a hexdump view of a fragment of the data Flash Player sends to the server after I close the Flex app:
00000130 ef bf bf ef bf bf ef bf bf ef bf bf ef bf bf ef |................|
00000140 bf bf ef bf bf ef bf bf ef bf bf ef bf bf ef bf |................|
00000150 bf ef bf bf ef bf bf ef bf bf ef bf bf ef bf bf |................|
Approach 2: I then tried it in air, but although the connection seems to initiate properly and I can go through the above trivial client-server interaction, after a few seconds, I get a SecurityErrorEvent. From what I've been able to follow of the docs, Air applications are trusted in this respect, and should not need to load security policy, right? I tried to add a call to Security.loadPolicy(), but it seems to be ignored. This is the message flow:
Received [class Event] connect
Received [class ProgressEvent] socketData
Received [class Event] close
Received [class SecurityErrorEvent] securityError
Security error: Error #2048: Security sandbox violation: app:/main.swf cannot load data from localhost:5432.
The Air version of my client code is below:
<?xml version="1.0" encoding="utf-8"?>
<mx:WindowedApplication xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute">
<mx:Script>
    <![CDATA[
        var str:Socket;
        private function handleClick(e:Event):void {
            Security.loadPolicyFile("xmlsocket://localhost:2525");
            str = new Socket('localhost', 5555);
            var message:String = 'hello';
            for (var i:int = 0; i < message.length; i++) {
                str.writeByte(message.charCodeAt(i));
            str.writeByte(0);
            str.flush();
            str.addEventListener(Event.ACTIVATE, handleEvent);
            str.addEventListener(Event.CLOSE, handleEvent);
            str.addEventListener(Event.CONNECT, handleEvent);
            str.addEventListener(Event.DEACTIVATE, handleEvent);
            str.addEventListener(IOErrorEvent.IO_ERROR, handleEvent);
            str.addEventListener(ProgressEvent.SOCKET_DATA, handleEvent);
            str.addEventListener(SecurityErrorEvent.SECURITY_ERROR, handleEvent);
        private function handleEvent(e:Event):void {
             trace("Received", Object(e).constructor, e.type);
             if (e is ProgressEvent) {
                 var strBytes:Array = [];
                 while(str.bytesAvailable > 0) {
                     var byte:int = str.readByte();
                     strBytes.push(byte);
                 trace(String.fromCharCode.apply(null, strBytes));
             } else if (e is SecurityErrorEvent) {
                 trace("Security error:", SecurityErrorEvent(e).text);
    ]]>
</mx:Script>
<mx:Button label="test" click="handleClick(event)"/>
</mx:WindowedApplication>
The server is in Java and is as follows:
import java.net.*;
import java.io.*;
public class DeadSimpleServer implements Runnable {
    public static void main(String[] args) throws Exception {
        if (args.length != 2) {
            throw new Exception("Usage: DeadSimpleServer policy-port service-port");
        int policyPort = Integer.parseInt(args[0]);
        int servicePort = Integer.parseInt(args[1]);
        new Thread(new DeadSimpleServer(policyPort,
                                        "<?xml version=\"1.0\"?>\n" +
                                        "<cross-domain-policy>\n" +
                                        "<allow-access-from domain=\"*\" to-ports=\"" + servicePort + "\"/>\n" +
                                        "</cross-domain-policy>\n"
                   ).start();
        new Thread(new DeadSimpleServer(servicePort, "world")).start();
        while (true) Thread.sleep(1000);
    private int port;
    private String response;
    public DeadSimpleServer(int port, String response) {
        this.port = port;
        this.response = response;
    public String getName() {
        return DeadSimpleServer.class.getName() + ":" + port;
    public void run() {
        try {
            ServerSocket ss = new ServerSocket(port);
            while (true) {
                Socket s = ss.accept();
                System.out.println(getName() + " accepting connection to " + s.toString());
                OutputStream outStr = s.getOutputStream();
                InputStream inStr = s.getInputStream();
                int character;
                System.out.print(getName() + " received request: ");
                while ((character = inStr.read()) != 0) {
                    System.out.print((char) character);
                System.out.println();
                Writer out = new OutputStreamWriter(outStr);
                out.write(response);
                System.out.println(getName() + " sent response: ");
                System.out.println(response);
                System.out.println(getName() + " closing connection");
                out.flush();
                out.close();
                s.close();
        } catch (Exception e) {
            System.out.println(e);
Am I missing something? From what I understand, either of these approaches should work, but I'm stuck with both. I have Flash Player 10,0,15,3 and am working with Flex / Air 3.0.0 under Linux.

So... apparently, with the Air approach, this is what I was missing: http://www.ultrashock.com/forums/770036-post10.html
It'd be nice if FlashPlayer gave us a nicer error here.
I'm still trying to figure out what the heck is going on in the web app (i.e., non-Air Flex) example. If anyone has any suggestions, that would be very helpful.

Need help on Socket and HTTP

Hi,
I need help ... please ... I have to use socket and not HTTPURLConnection
I try to connect with a socket to a web server (apache2) and request one page but two times.
The first time it works well but the second one it doesn't ... I get a null message.
Why ?
Does the server close the socket as soon as the page is sent ?
If it doesn't how I can continue sending and receiving data on the same socket ?
Here is my code:
package test;
import java.net.*;
import java.io.*;
public class Test
private String laRequete = new String(
"POST http://localhost:5577/Test/ HTTP/1.0\r\n"+
"Host:localhost:5577\r\n"+
"\r\n");
PrintWriter laSortie;
BufferedReader lEntree;
Socket laSocketTCP;
public Test()
String tmp;
try
laSocketTCP = new Socket("localhost", 5577);
laSortie = new PrintWriter(laSocketTCP.getOutputStream());
lEntree = new BufferedReader(new InputStreamReader(laSocketTCP.getInputStream()));
laSortie.println(laRequete);
laSortie.flush();
// Premier essai OK
System.out.println(lEntree.readLine());
while((tmp = lEntree.readLine()) != null)
System.out.println(tmp);
// Second essai => Not OK
laSortie.println(laRequete);
laSortie.flush();
System.out.println(lEntree.readLine());
while((tmp = lEntree.readLine()) != null)
System.out.println(tmp);
catch (Exception e)
e.printStackTrace();
public static void main(String args[])
Test tp = new Test();
Here is the result of the execution
HTTP/1.1 200 OK
Date: Wed, 29 Sep 2004 08:35:35 GMT
Server: Apache/2.0.51 (Win32)
Last-Modified: Wed, 29 Sep 2004 08:27:57 GMT
ETag: "23a46-9a-56c93f9a"
Accept-Ranges: bytes
Content-Length: 154
Connection: close
Content-Type: text/html; charset=ISO-8859-1
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<TITLE> Index Test 1 </TITLE>
</HEAD>
<BODY>
Test 1
</BODY>
</HTML>
null
Thanks, bye.

Send an HTTP 1.1 request instead of a 1.0 request.
HTTP 1.0 does not support keeping the connection open, so yes, the server closes the connection.
Dave.

Hidden network drives "home" and "net" shown in folder view Adobe Bridge CS5 / Lion Problem

Updated to Mac OS X 10.7.2 Lion and got this "problem":
The hidden network drives "home" and "net" shown in folder view Adobe Bridge CS5 (unlike in 10.6 Snow Leopard).
Normally these network drives are hidden (in Finder and other Apps) - but Adobe Bridge CS5 is showing them, despite "show hidden files" is unchecked in Adobe Bridge.
Not a dramatic "bug", but it also shouldn't be a big problem for Adobe Bridge engineers to solve this. My first question to the Adobe Support was answered like: "we don't know what Apple did change, so we cannot do anything". Hmmm, are you serious?
I tried to resolve that problem by myself but failed. So, if an Adobe engineer is reading this post: perhaps Adobe Bridge is ignoring the automounter master map (that was my approach to resolve it):
# Automounter master map
+auto_master                    # Use directory service
/net           -hosts                 -nobrowse,hidefromfinder,nosuid
/home                                        auto_home       -nobrowse,hidefromfinder
/Network/Servers               -fstab
/-                              -static
You cannot do anything to these folders, so it is not a serious issue, but, I mean, did someone at Adobe check compatibiliy with 10.7 and ignored this issue? If so, are there an other issues ignored?
But I guess, the compatibilty update for Bridge CS5 for Lion is Bridge CS6 - to be fair: I also have to say, that in general Bridge is running okay on Mac OS X 10.7.2 (but could be better, as always;)

Hi Curt Y,
thanks for your answer! Yes you' re right, I forgot to mention that ... before I posted here, I sent a bug report via the Apple Bug Report webpage about the issue ... of course, here are 2 parties involved.
I had a similiar problem once and I got a meesage back from Apple: "that it is a 3rd party problem, sorry" (it was about color management).
I am just a user and I often feel very strange about Apple's (topsecret) communication behaviour ... Whatever, what do I know about software engineering? - Right.
Maybe someone on this forum has an idea, because I'm afraid, thus it is not a serious bug, no one would take care about it in the next time (during my research I found an older post here on the forum about the same problem ...).
thanks for help in advance,
jobumac

Implementing sockets and threads in a jframe gui program

Hi, I am trying to find a solution to a problem I am having designing my instant messenger application.
I am creating listening sockets and threads for each client logged into the system. i want to know if there is a way to listen to other clients request from the main gui and then if another client tries to establish a connection with me for example, a thread is created for that client and then my chat gui opens automatically has soon has the other client sends his or hers first text message to me.
I am relatively new at socket programming has I am currently studying along this area. I know how to create threads and sockets but I am having trouble finding out a solution to my problem. Here is the code that I have done so far for the listening method from my main gui, and the thread class of what I have done so far.
listening socket:
     private void listeningSocket()
            ServerSocket serverSocket = null;
            boolean listening = true;
            try
                //listen in port 4444;
                serverSocket = new ServerSocket(4444);
            catch(IOException x)
                JOptionPane.showMessageDialog(null, "cannot listen to port 4444", null, JOptionPane.ERROR_MESSAGE);
            while(listening)
                client_thread w;
                try
                   w = new client_thread(serverSocket.accept(), jTextArea1);
                   Thread t = new Thread(w);
                   t.start();
                catch(IOException x)
                     JOptionPane.showMessageDialog(null, "error, cannot start new thread", null, JOptionPane.ERROR_MESSAGE);
        }thread class:
import java.io.*;
import java.net.*;
import javax.swing.*;
import java.sql.*;
import java.awt.event.*;
* @author jonathan
public class client_thread extends Thread
     //define new socket object
    private Socket client_user = null;
    private JTextArea textArea;
    public client_thread(Socket client_user, JTextArea textArea)
        this.client_user = client_user;
        this.textArea = textArea;
    public void run()
        BufferedReader in = null;
        PrintWriter out = null;
        String error = "error has occured, messege was not sent";
        String messege = null;
         try
            //create input and output streams
            in = new BufferedReader(new InputStreamReader (client_user.getInputStream()));
            out = new PrintWriter(client_user.getOutputStream(), true);
            while(true)
               //read messege sent by user
               messege = in.readLine();
                //display messege in textfield
               out.println(messege);
               textArea.append(messege);
        catch (IOException e)
            //error messege
            JOptionPane.showMessageDialog(null, error, null, JOptionPane.ERROR_MESSAGE);
}

Seems like all you need to do is create a new dialog for each socket that is established. Your current design looks like it will attempt to use the same textarea for all the sockets.
I would say in your thread class do the following:
MyConversationDialog dialog = new MyConversationDialog();
while(true)
               //read messege sent by user
               messege = in.readLine();
                //display messege in textfield
               out.println(messege);
               dialog.setVisible (true);
               dialog.addMessage (message);
            }

Sockets and timing out

Hello
I wish to continue processing stuff, if my socket is inactive for 10 seconds. I'll achieve this with the following method:
setSoTimeout(int timeout)
Out of interest wis there a default timeout for a socket and if so how long is it?
Cheers
Steve

take a look at setSoTimeout()
http://java.sun.com/j2se/1.4/docs/api/java/net/Socket.html#setSoTimeout(int)

Sockets and lockups in applets.

I've handed this project in a while aog now, and it had partial functionality. I was however wondering why I came accross this same recurring problem?
I believe i have set my loops in the correct places but my applet seems to 'lock up' after one result is returned.
If anyone can shed some light on this (I think the applet is resetting the connection each time?) I would be most grateful.
This is the server
import java.io.*;
import java.net.*;
public class PizzaExpressServer {
     public static void main (String []args){
          try
               ServerSocket   SS = new ServerSocket(6000);
               Socket   sts = SS.accept();
               DataInputStream isfc = new DataInputStream(sts.getInputStream());
               DataOutputStream ostc = new DataOutputStream(sts.getOutputStream());
               while(true) {
                    int select = isfc.readInt();
                    System.out.println("Selection received from client " + select);
                   double total = 0.0;
                switch(select){
                case 1: total += 2; break;
                    case 2: total += 3; break;
                    case 3: total += 4; break;
                    case 4: total += 5; break;
                    case 5: total += 0.5; break;
                    case 6: total += 0.5; break;
                    case 7: total += 0.5; break;
                    case 8: total += 0.5; break;
                    case 9: total += 0.5; break;
                    case 10: total = 0; break;
                    ostc.writeDouble(total);
                    ostc.flush();
                    System.out.println("Price of Pizza is: " + total);
} catch (IOException e) {
               System.out.println(e);
And here is the client...
//<title> Pizza Express </title>
//<applet code="PizzaExpress.class"
//     width=300 height=200>
//</applet>
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.*;
public class PizzaExpress extends Applet implements ItemListener {
   private CheckboxGroup One;
   private Checkbox small, medium, large, Family, Ham, Pineapple, Chicken, Sweetcorn, ExtraChesse, Reset;
   private double total;
   private int selection;
   private TextField tf;
   Panel Top = new Panel();
   Panel Bottom = new Panel();
   public void init(){
    One = new CheckboxGroup();
     add (new Label(" Select pizza size   "));
     Panel Top = new Panel();
    Panel Bottom = new Panel();
     small = new Checkbox("Small", One, false);
     add(small);
     small.addItemListener(this);
    medium = new Checkbox("Medium", One, false);
     add(medium);
     medium.addItemListener(this);
     large = new Checkbox("Large", One, false);
     add(large);
     large.addItemListener(this);
     Family = new Checkbox("Family", One, false);
     add(Family);
     Family.addItemListener(this);
     Ham = new Checkbox("Ham");
     add(Ham);
     Ham.addItemListener(this);
     Pineapple = new Checkbox("Pineapple");
     add(Pineapple);
     Pineapple.addItemListener(this);
     Chicken = new Checkbox("Chicken");
     add(Chicken);
     Chicken.addItemListener(this);
     Sweetcorn = new Checkbox("Sweetcorn");
     add(Sweetcorn);
     Sweetcorn.addItemListener(this);
     ExtraChesse = new Checkbox("ExtraChesse");
     add(ExtraChesse);
     ExtraChesse.addItemListener(this);
     Reset = new Checkbox("Reset");
     add(Reset);
     Reset.addItemListener(this);
     tf = new TextField(30);
     add(tf);
    Top.add(small);
     Top.add(medium);
     Top.add(large);
     Top.add(Family);
     Bottom.add(Ham);
    Bottom.add(Pineapple);
    Bottom.add(Chicken);
    Bottom.add(Sweetcorn);
     Bottom.add(ExtraChesse);
     Bottom.add(tf);
     Bottom.add(Reset);
    add(Top);
     add(Bottom);
   public void itemStateChanged(ItemEvent e) {
      try
       Socket NS = new Socket(getCodeBase().getHost(), 6000);
       DataInputStream Dis = new DataInputStream(NS.getInputStream());
       DataOutputStream Dos = new DataOutputStream(NS.getOutputStream());
       if (e.getSource() == small){
          selection = 1;}
      if (e.getSource() == medium){
          selection += 2;}
      if (e.getSource() == large){
          selection += 3;}
      if (e.getSource() == Family){
          selection += 4;}
       if (e.getSource() == Ham){
          selection += 5;}
        if (e.getSource() == Pineapple){
          selection += 6;}
        if (e.getSource() == Chicken){
          selection += 7;}
       if (e.getSource() == Sweetcorn){
          selection += 8;}
       if (e.getSource() == ExtraChesse){
          selection += 9;}
        if (e.getSource() == Reset){
          selection = 10;}
      Dos.writeInt(selection);
       Dos.flush();
       total = Dis.readDouble();
       tf.setText("Pizza total is ?" + total);
       } catch (IOException ex) {
               System.out.println(ex);}
}I've included some HTML in at the top for easy running.

If your code hangs somewhere, find out where. Put in some debugging println()'s to zero in on the line where it hangs.
Looking at the code quickly, one bug seems to be that you open sockets and streams and never close them. Do that in both the server and in the client.
You probably want to put your accept() call inside the loop, and close the accepted socket after you are done.

Need to use only one sender and receiver communication channel.

Hello Experts.
I have a scenario where in I have to use only one sender and receiver communication channel to push files from different source directories to different receiver directories.
For Eg;
Sender
D://dir1/file1 --->                  E://dir1/File1
F://dir2/file2 ---->                 G://dir2/file2
H://dir3/file3----->                 I://dir3/file3.
Can this be achieved by using pass through scenario?
Please let me know if the requirement is not clear.
Thanks in advance.
Advit Ramesh

Hi Advit,
I think it is possible. You have to use the Advanced Selection for Source file in the sender channel to define multiple files to be picked up. Also, the Dynamic configuration must also be enabled and used in the mapping so you can manipulate the target directory and target file name based on your source files.
For Polling from multiple directories:
http://wiki.scn.sap.com/wiki/display/XI/File+Sender+Adapter+-+Polling+Multiple+Directories
Dynamic Configuration:
Dynamic file name and directory in Receiver File Adapter - summary of possibilities - Process Integration - SCN Wiki

Welcome to the Design and Architecture Community

Welcome to the Network Infrastructure Design and Architecture Community. We encourage everyone to share their knowledge and start conversations on design and overall network topology. All topics are welcome, including requirements and constraints of the network, tools and techniques, issues of hierarchy, leading practices, services, build strategies, architectures and solutions to solve business problems.
Remember, just like in the workplace, be courteous to your fellow forum participants. Please refrain from using disparaging or obscene language or posting advertisements.
Cheers,
Dan BruhnCSC Community Manager

been waiting to see a forum like this. This forum should amalgamate all the other areas like R&S, security, DC design, and provide more quality , proven solns and discuss problems/challenges as well. Will be following this forum regularly
thanks dan for creating this community
Regards Kishore

Is it possible to download iOS 5 from one iMac and not get them totally wiped of apps and stuff. We have an iPad each and a communal email address and an iCloud address each. One iPad now is totally screwed up.

Is it possible to download iOS 5 from one iMac on two ipads and not get them totally wiped of apps and stuff. We have an iPad each and a communal email address and an iCloud address each. One iPad now is totally screwed up.

Thank you for your reply.
I am somewhat new to iOS and OS having grown up with DOS and Windows. I am not familiar with IMAP and iCloud and I am not even sure which types of servers my various emails use.
The problem I would anticipate with iCloud is that (I assume) it would limit my access to data (including mail) on the iCloud to when I happen to be logged onto the internet. I also assume(?) that large files (photos etc.) would require some time to download whenever I wish to access them from whichever device I happen to be using (I hope I am wrong about this).
I have kept my devices to 500gb - 1TB for OS and 32gb - 128gb for iOS but since I have pretty slow WiFi (shared with DirecTV Whole Home and Netflix streaming) it is my impression that iCloud might be quite limited due to data transfer times.
Perhaps a factor would be that I have 2 DSL lines and my main DSL line is connected to two wireless routers (to also provide WiFi in a metal building that blocks WiFi and Cellular signals)
I may be totally wrong in my assumptions regarding iCloud. My mail is not so urgent that I need access to it instantly and I could wait until I had internet access or I can get it on my iPhone. My main concern with iCloud would be my data files (Word, Pages, Excel, Numbers etc.).
On the other hand, if I wanted to keep my 10,000 emails that would take up a lot of iCloud memory and I don't know how to measure how much storage it would take or how to move Hotmail or even iCloud mail to iCloud.
It may take me some time to figure this out.

GPIB and RS232 communication problems

I've been having several "interesting" problems with GPIB and RS232 communications in LabVIEW VIs. Some I'll mention at the end for curiosity, but right now I'm facing a rather big problem. I'm essentially self-taught at doing LabVIEW (using 8.5.1 right now), but by now I've had a lot of experience as their either has not been any drivers or pre-made VIs for the instruments I've needed or I've not been able to get the available drivers to work and had to write my own anyway (such as with the HP 3458A), but nothing seems to be working right now. I'm not at work, but we typically find forum sites blocked anyway (I can't even download the NI drivers at work since they house them on a ftp server, go figures) so I can't give the VI itself (it wouldn't be easy to get approval even if I could) so the best I can do right now is in words describe everything I've tried. I will be happy to post follow-ups of specific details if I can if they would be helpful.
I've been working on a routine to read data from an MKS 670 Signal Conditioner/Display with a MKS 274 Multiplexer with 3 connected MKS 690A Baratrons. Previously I've worked on programs using other older displays and the analog outputs which were being read by a DAQ card, but for a new project it was decided to try and just read the data directly. I first worked with a unit with just an RS232 Serial Port which I managed to get to work, but had so much problems with garbage readings and having to add checks and re-reads that by the end no matter what delays I added between each reading and how simplified the command routine down to just 2 sequences and the read that it took at least 10 seconds to get 1 reading from each channel.
Figuring maybe it was a limitation of the serial communications for these instruments I tried to re-work it for a unit with a GPIB port with which I'm actually much more familiar. The problem is that I cannot get anything at all from the unit through GPIB. Everything even the bare-bones built-in GPIB CLR function times out with no response from the instrument no matter how long I set the timeout limit and it also freezes the entire GPIB bus as well. It isn't a waiting issue as it freezes on the very first command. The GPIB initialization function seems to work (I typically find this to be unnecessary), but the instrument itself doesn't even respond with a status code. I've also tried just the basic GPIB write functions with even just passing the <cr> and <lf> characters as well. In Measurement and Automation Explorer most of the time the instrument won't even appear when doing search for instruments and when it does it shows as not responding to the *IDN? command (yes I've messed with the EOI, EOS, etc settings and I've even changed the GPIB address even though when it gets this far it confirms that I have the correct address) and even tried manually doing the *IDN?, *RST, and *CLR commands even with <cr> and <lf> characters which the manual for these units clearly states are compatible commands and NI SPY and everything show no response at all. I've tried 2 different GPIB units, 3 different computers including several that are not online and haven't been updated for a while, and using older LabVIEW versions, extensive re-booting and resetting of computers and devices and still nothing. I'm using an NI GPIB-USB-HS GPIB to USB adaptor which I've used extensively on other systems and even re-connected to those systems and everything worked fine. When I hooked up equipment that I knew was working, it would either freeze the entire GPIB bus until well past whatever timeout setting I set at which point all the instruments would appear, but none responding to *IDN? queries or nothing would appear at all, or if I manually turned it off when frozen the other instruments would work and most even respond to the *IDN? queries. The same goes for both of the GPIB instruments of this type that I tried and again for different versions of LabVIEW, difference computers (all Windows XP though), and every GPIB configuration setting I can find to mess with in every combination.
Any thoughts or suggestions would be greatly appreciated. I've had all sorts of weird problems with equipment and LabVIEW (you've got to love undocumented design features) that have frustrated me before, but I've never had an instrument never respond at all especially a GPIB one. Getting garbage yes, no response at all, no.
The side side issues I'm just mentioning as they may be related, but I'm really interested in the above as I have working solutions for these:
One I've had is with a Hart Scientific (prior to being bought by Fluke) 1560 Black Stack that would continually stop responding to GPIB commands when on a continual read function taking readings just every 4 seconds with 250ms between each GPIB read or write command but for up to hours in total and the times it stops responding are random as far as I can tell. I even started sending the *RST command before and after every read or write command and still it freezes. The only thing is to manually turn it off and then back on or manually go through the menus and manually trigger the GPIB reset routine at which point it immediately starts responding. However, when I got sick of having to babysit it and just decided to try the RS232 serial port (as that is all it has without the extended communications module) it works fine no problem and I can even get readings slightly faster from it. Using a Hart Scientific 1529 Chub-e it could give me data on all 4 channels every second without problems. I just find it a bit odd.
When I couldn't get any of the HP 3458A driver packs to work to even give a single measurement reading and just made my own using basic GPIB read/write commands using the programming manual I still have a few interesting problems in randomly when reading off the full possible 256 bytes on the bus and clearing the bus I often find garbage partial readings on the bus every now and then. I've added a few routines to do some basic checks, but it is annoying. What is really weird is when just doing basic DC Voltage reads the "-" sign will randomly be dropped from some readings (started as about 1 out of every 5, down now to about 1 out of every 10). Fortunately I'm taking several readings and averaging and taking the standard deviation with limits on the deviations and basically added a routine to say if there is even 1 negative number take the absolute value of all then make all negative, but again I find it weird.
Thanks.
-Leif
Leif King
Metrology Engineer
Oak Ridge Metrology Center

Greetings Leif,
I understand you have completed extensive troubleshooting techniques to pin-point the problem with the GPIB communication. To begin, I want to ask you a few questions to help me understand your set-up and the issue at hand.
1) Is the NI GPIB-USB-HS cable the one which cannot communicate with your instrument?
2) When using the GPIB-USB-HS, does the GPIB interface show up in MAX?
3) If yes, does the instrument appear in MAX after scanning for instruments (from what I understand in your issue, it does so in an intermittent manner..)?
4) What driver version of VISA do you have installed in your computer?
5) Are you able to communicate to the same instrument using another GPIB cable?
Thank you for trying out some of these steps again, but we want to make sure we rule out other aspects in the systems which might be affecting the GPIB communication.
As for your other issues, please post seperate threads for each so we can help you accordingly. Thanks!
Sincerely,
Aldo
Aldo A
Applications Engineer
National Instruments

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