RegisterTCPServer and ConnectToTCPServer

I deal mainly in the LabVIEW world, but I'm having to translate some CVI code (the server side) to LabVIEW, and I'm trying to understand one piece of the CVI code first. In the server side, there is a call to RegisterTCPServer
else if ((status = RegisterTCPServer (xxTCP_PORT, xxTCP_Callback, NULL)) < 0)
and on the client side there is a call to ConnectToTCPServer
ConnectToTCPServer (TCPHandle, xxTCP_Port, "xxName", yyTCP_Callback)
The part that is unclear to me is that the client and server are on different computers, and the Client seems to specify a serverHostName (in this example, xxName), but the Server's call to RegisterTCPServer only has the Port number in common with the Client. I'm thinking that since no serverHostName is specified, it would default to localhost. So, why does the client (in this example) specify the serverHostName? Is the port number sufficient for the server/client to find each other, or is there some CVI call I should be searching for in the (server) code that must be being called somewhere that named the server to the samething the client is looking for?

As is clearly explained in the online help for the function, RegisterTCPServer
Registers your program as a valid TCP server and allows other applications to connect to it for network communication.
Clients attempting to connect to your program must use the same port number. Thereafter, all requests by the client are routed through the specified server callback function. You can register your program as a TCP server multiple times as long as you specify different port numbers.
On the server side you do not need the host name simply because you are the host!
On the contrary, on the client side you need to know the server name (together with the port number) so that your messages are properly routed to the correct machine: it could be the same machine or a different PC over the network.
Proud to use LW/CVI from 3.1 on.
My contributions to the Developer Zone Community
If I have helped you, why not giving me a kudos?

Similar Messages

ConnectToTCPServer Failure in Windows7

I am using "Measurement Studio Version 6.0, Labwindows/CVI" for my TcpIP Server and Client Program.
It works very well in the Windows XP circumstance using below functions.
But the function ConnectToTCPServer fails with error message like below, whereas RegisterTCPServer works successfully at Windows XP and Windows 7 OS.
I tried ConnectToTCPServer function at three computer, which results in same error message.
I am looking for anyone like an angel who can help me. Thanks.
<server side>
RegisterTCPServer(6000, Server1Callback, 0);
<client side>
unsigned int handle;
ConnectToTCPServer (&handle, 6000, "172.29.24.182", ClientCallback,NULL, 5000);
<error message at client side>
Non-fatal run-time error
Library function error (return value == -2 [0xfffffffe]).
Unable to establish conneciton

Hi seong-yeon
Did you confirmed if that port is available? Also try the computer name as the server host name in ConnectToTCPServer.
Do you have all firewalls disabled? You can confirm with your IT department if there is any network security installed.
This article discuss how to build applications with the TCP Support library and offers a couple of examples you can try to test the connection between the client and the server.
Regards
Chris S.

TCP/IP Library and Windows 7

Hi together,
I have the following problem: I am trying to build up TCP/IP connections as client. On my notebook (WindowsXP) everything works like a charm. But when I install the application on a Windows 7 PC, no connection is possible.
ConnectToTCPServer fails with "WSAE_UNKNOWN".
Probably this has to do with the socket handling from Win 7. Currently I still have the Measurement Studio Ver. 6.0 on my notebook, because my applications always worked fine on WinXP PCs.
So my question is: Is this a known behavior? If so, is there a workaround or is the only solution a newer CVI Version?
Thanks for any help,
Dirk

Hello Robert,
thanks for your answer.
To give a some more details:
I can´t say if it is happening with trying to use any TCP from CVI. Because if the application is running on an WinXP PC (my notebook, even installed from the distribution kit) everything is fine. On a Windows 7 PC my application already fails on the ConnectToTCPServer call with the above mentioned error. With PuTTY I can establish TCP connections, a python script (though I am not sure if my python supports Win 7) shows the same problem.
Some more details about the task: I have to establish two TCP connections as client, one to my data acquisition hardware, second one to a TCP Server provided by automationX (some soft-sps solution). If I run my application on my notebook with WinXP everything works fine (even the automationX stuff I connect to is running on a Windows 7 PC). Now I install the application on a Windows 7 PC and both ConnectToTCPServer calls fail with the above mentioned error. So I have no chance to test other TCP calls from the library.
Actually this behavior makes me think that is a problem with the Winsock of Windows 7. Why otherwise it would run on my XP notebook and would fail on the ConnectToTCPServer on the Windows 7 PC?
Unfortunately, being in Asia atm, I only have the CVI 6 version with me. I will travel back to Germany next week. I have the upgrades up to CVI 9 there, but I never installed them. (Never change a running system ) On the other hand, probably it is time to do so. Never had to work with Win 7 before.
I just wanted to know if anyone else experienced some similar problems and if there is a workaround (maybe even in Win 7 to make the socket behavior / handling like it was on WinXP).
But I guess I have to finally install the upgrades.
Is CVI 9 compatible / tested with Windows 7?
Best regards,
Dirk

ConnectToTCPServer

Hi,
Could someone help?
Why am I getting a library function error
if (ConnectToTCPServer (&g_hconversation, portNum, serverHostName, clientTCP, NULL, 5000) <0
     return 0;
portNum is 5000
serverHostName is 192.168.2.3 and I can ping it.
my clientTCP function is:
int clientTCP (unsigned handle, int event, int error, void *callbackData)
    char receiveBuf[256] = {0};
    int dataSize         = sizeof(receiveBuf)-1;
char lineBuf[130];
    switch (event)
        case TCP_DATAREADY:
#if 0
            if ((dataSize = ClientTCPRead (g_hconversation, receiveBuf, dataSize, 1000)) < 0)
    return -1;
   printf("TCP_DATAREADY received: %s\n",receiveBuf);
#endif
            break;
        case TCP_DISCONNECT:
   if(error)
    sprintf(lineBuf,"TCP_DISCONNECT received due to error= %d\n", error);
    PRINT_DBG(lineBuf);
       g_hconversation = INVALID_TCP_HANDLE;
   else
    PRINT_DBG("TCP_DISCONNECT received from TcpServer\n");
            break;
        default:
        printf("default received\n");
        break;
    return 0;

Hello agyna,
which error are you receiving and where? Does it happens every time you run the code?
Proud to use LW/CVI from 3.1 on.
My contributions to the Developer Zone Community
If I have helped you, why not giving me a kudos?

A problem with Threads and loops.

Hi, I have some code that needs to be constantly running, like while(true)
      //code here
}However, the code just checks to see if the user has input anything (and then if the user has, it goes to do some other stuff) so I don't need it constantly running and hogging up 98% of the CPU. So I made my class (which has the method that needs to be looped, call it ClassA) implement Runnable. Then I just added the method which needed to be looped into the public void run()
I have another class which creates an instance of the above class (call it ClassB), and the main(String[] args) is in there.
public static void main(String[] args)
          ClassA test = new ClassA();
          Thread thread = new Thread(test.getInstanceOfClassA());
          thread.start();
          while(true)
                       //I do not know what to put here
               try
                    thread.sleep(100);
               catch(InterruptedException iex)
     }However, the thread only calls run() once,(duh...) but I can't think of away to get it to run - sleep - run -sleep forever. Can someone help me?

Hi, I have some code that needs to be constantly
running, like while(true)
//code here
}However, the code just checks to see if the user has
input anything (and then if the user has, it goes to
do some other stuff) so I don't need it constantly
running and hogging up 98% of the CPU. Where does the user input come from. Are you reading from an InputStream? If so, then your loop will be blocked anyway when reading from the InputStream until data is available. During that time, the loop will not consume processor cycles.
public static void main(String[] args)
          ClassA test = new ClassA();
Thread thread = new Thread(test.getInstanceOfClassA());I have never seen this idiom. If ClassA instanceof Runnable, you simply write new Thread(test).
          thread.start();
          while(true)
//I do not know what to put
do not know what to put here
               try
                    thread.sleep(100);
               catch(InterruptedException iex)
     }However, the thread only calls run() once,(duh...)Yeah, why would you want to call it more than once given that you have an infinite loop in ClassA.run()?
Harald.
Java Text Crunching: http://www.ebi.ac.uk/Rebholz-srv/whatizit/software

A problem with Threads and MMapi

I am tring to execute a class based on Game canvas.
The problem begin when I try to Play both a MIDI tone and to run an infinit Thread loop.
The MIDI tone "Stammers".
How to over come the problem?
Thanks in advance
Kobi
See Code example below:
import java.io.IOException;
import java.io.InputStream;
import javax.microedition.lcdui.Graphics;
import javax.microedition.lcdui.Image;
import javax.microedition.lcdui.game.GameCanvas;
import javax.microedition.media.Manager;
import javax.microedition.media.MediaException;
import javax.microedition.media.Player;
public class MainScreenCanvas extends GameCanvas implements Runnable {
     private MainMIDlet parent;
     private boolean mTrucking = false;
     Image imgBackgound = null;
     int imgBackgoundX = 0, imgBackgoundY = 0;
     Player player;
     public MainScreenCanvas(MainMIDlet parent)
          super(true);
          this.parent = parent;
          try
               imgBackgound = Image.createImage("/images/area03_bkg0.png");
               imgBackgoundX = this.getWidth() - imgBackgound.getWidth();
               imgBackgoundY = this.getHeight() - imgBackgound.getHeight();
          catch(Exception e)
               System.out.println(e.getMessage());
      * starts thread
     public void start()
          mTrucking = true;
          Thread t = new Thread(this);
          t.start();
      * stops thread
     public void stop()
          mTrucking = false;
     public void play()
          try
               InputStream is = getClass().getResourceAsStream("/sounds/scale.mid");
               player = Manager.createPlayer(is, "audio/midi");
               player.setLoopCount(-1);
               player.prefetch();
               player.start();
          catch(Exception e)
               System.out.println(e.getMessage());
     public void run()
          Graphics g = getGraphics();
          play();
          while (true)
               tick();
               input();
               render(g);
      * responsible for object movements
     private void tick()
      * response to key input
     private void input()
          int keyStates = getKeyStates();
          if ((keyStates & LEFT_PRESSED) != 0)
               imgBackgoundX++;
               if (imgBackgoundX > 0)
                    imgBackgoundX = 0;
          if ((keyStates & RIGHT_PRESSED) != 0)
               imgBackgoundX--;
               if (imgBackgoundX < this.getWidth() - imgBackgound.getWidth())
                    imgBackgoundX = this.getWidth() - imgBackgound.getWidth();
      * Responsible for the drawing
      * @param g
     private void render(Graphics g)
          g.drawImage(imgBackgound, imgBackgoundX, imgBackgoundY, Graphics.TOP | Graphics.LEFT);
          this.flushGraphics();
}

You can also try to provide a greater Priority to your player thread so that it gains the CPU time when ever it needs it and don't harm the playback.
However a loop in a Thread and that to an infinite loop is one kind of very bad programming, 'cuz the loop eats up most of your CPU time which in turn adds up more delays of the execution of other tasks (just as in your case it is the playback). By witting codes bit efficiently and planning out the architectural execution flow of the app before start writing the code helps solve these kind of issues.
You can go through [this simple tutorial|http://oreilly.com/catalog/expjava/excerpt/index.html] about Basics of Java and Threads to know more about threads.
Regds,
SD
N.B. And yes there are more articles and tutorials available but much of them targets the Java SE / EE, but if you want to read them here is [another great one straight from SUN|http://java.sun.com/docs/books/tutorial/essential/concurrency/index.html] .
Edited by: find_suvro@SDN on 7 Nov, 2008 12:00 PM

Problem with Threads and a static variable

I have a problem with the code below. I am yet to make sure that I understand the problem. Correct me if I am wrong please.
Code functionality:
A timer calls SetState every second. It sets the state and sets boolean variable "changed" to true. Then notifies a main process thread to check if the state changed to send a message.
The problem as far I understand is:
Assume the timer Thread calls SetState twice before the main process Thread runs. As a result, "changed" is set to true twice. However, since the main process is blocked twice during the two calls to SetState, when it runs it would have the two SetState timer threads blocked on its synchronized body. It will pass the first one, send the message and set "changed" to false since it was true. Now, it will pass the second thread, but here is the problem, "changed" is already set to false. As a result, it won't send the message even though it is supposed to.
Would you please let me know if my understanding is correct? If so, what would you propose to resolve the problem? Should I call wait some other or should I notify in a different way?
Thanks,
B.D.
Code:
private static volatile boolean bChanged = false;
private static Thread objMainProcess;
   protected static void Init(){
        objMainProcess = new Thread() {
            public void run() {
                while( objMainProcess == Thread.currentThread() ) {
                   GetState();
        objMainProcess.setDaemon( true );
        objMainProcess.start();
    public static void initStatusTimer(){
        if(objTimer == null)
             objTimer = new javax.swing.Timer( 1000, new java.awt.event.ActionListener(){
                public void actionPerformed( java.awt.event.ActionEvent evt){
                          SetState();
    private static void SetState(){
        if( objMainProcess == null ) return;
        synchronized( objMainProcess ) {
            bChanged = true;
            try{
                objMainProcess.notify();
            }catch( IllegalMonitorStateException e ) {}
    private static boolean GetState() {
        if( objMainProcess == null ) return false;
        synchronized( objMainProcess ) {
            if( bChanged) {
                SendMessage();
                bChanged = false;
                return true;
            try {
                objMainProcess.wait();
            }catch( InterruptedException e ) {}
            return false;
    }

Thanks DrClap for your reply. Everything you said is right. It is not easy to make them alternate since SetState() could be called from different places where the state could be anything else but a status message. Like a GREETING message for example. It is a handshaking message but not a status message.
Again as you said, There is a reason I can't call sendMessage() inside setState().
The only way I was able to do it is by having a counter of the number of notifies that have been called. Every time notify() is called a counter is incremented. Now instead of just checking if "changed" flag is true, I also check if notify counter is greater than zero. If both true, I send the message. If "changed" flag is false, I check again if the notify counter is greater than zero, I send the message. This way it works, but it is kind of a patch than a good design fix. I am yet to find a good solution.
Thanks,
B.D.

Problem with Threads and "plase wait..."-Window

Hi everyone,
I have a problem that I'm not able to solve in any way... I have a time-consuming task (a file decryption) which I execute in a separate thread; I've used the SwingWorker class, like suggested by sun-tutorial, and it works right. The problem is that I have to wait that the decryption have finished before continuing with program-execution. Therefore I would like to display a "please wait"-window while the task runs. I've tryed all the possible ways I know but the problem is always the same: the waitWindow is displayed empty, the bounds are painted but the contents no; it's only painted when the decrypt-task has finished. Please help me, I have no more resources....
decrypt-file code:
public class DecryptFile {
private String cryptedFileNameAndPath;
private ByteArrayInputStream resultStream = null;
// need for progress
private int lengthOfTask;
private int current = -1;
private String statMessage;
public DecryptFile(String encZipFileNameAndPath) {
    cryptedFileNameAndPath = encZipFileNameAndPath;
    //Compute length of task...
    // 0 for indeterminate
    lengthOfTask = 0;
public ByteArrayInputStream getDecryptedInputStream() {
    return this.resultStream;
   * Called from ProgressBarDemo to start the task.
public void go() {
    current = -1;
    final SwingWorker worker = new SwingWorker() {
      public Object construct() {
        return new ActualTask();
    worker.start();
   * Called from ProgressBarDemo to find out how much work needs
   * to be done.
public int getLengthOfTask() {
    return lengthOfTask;
   * Called from ProgressBarDemo to find out how much has been done.
public int getCurrent() {
    return current;
public void stop() {
    current = lengthOfTask;
   * Called from ProgressBarDemo to find out if the task has completed.
public boolean done() {
    if (current >= lengthOfTask)
      return true;
    else
      return false;
public String getMessage() {
    return statMessage;
   * The actual long running task. This runs in a SwingWorker thread.
class ActualTask {
    ActualTask () {
      current = -1;
      statMessage = "";
      resultStream = AIUtil.getInputStreamFromEncZip(cryptedFileNameAndPath); //here the decryption happens
      current = 0;
      statMessage = "";
}The code that calls decryption and displays waitWindow
      final WaitSplash wS = new WaitSplash("Please wait...");
      final DecryptFile cryptedTemplate = new DecryptFile (this.templateFile);
      cryptedTemplate.go();
      while (! cryptedTemplate.done()) {
        try {
          wait();
        } catch (Exception e) { }
      this.templateInputStream = cryptedTemplate.getDecryptedInputStream();
      wS.close();Thanks, thanks, thanks in advance!
Edoardo

Maybe you can try setting the priority of the long-running thread to be lower? so that the UI will be more responsive...

Problem with threads and graphics

I have a thread that chooses paths for a Travelling salesman problem, it then calls a TSPdraw class and passes it the path, which the class then draws. the problem is when i have two threads it creates two windows but only draws a path in one of them. any ideas where i`m going wrong

Are you using swing components? Swing isn't threadsafe. If you have multiple threads that want to update your UI you need to use the SwingUtilities.invokeLater(...)or invokeAndWait(...). There is a page in the swing tutorial about this at: http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html

Problem with threads and ProgressMonitor

Dear Friends:
I have a little problem with a thread and a ProgressMonitor. I have a long time process that runs in a thread (the thread is in an separate class). The thread has a ProgressMonitor that works fine and shows the tasks progress.
But I need deactivate the main class(the main class is the user interface) until the thread ends.
I use something like this:
LongTask myTask=new LongTask();
myTask.start();
myTask.join();
Now, the main class waits for the task to end, but the progress monitor don`t works fine: it shows only the dialog but not the progress bar.
What's wrong?

Is the dialog a modal dialog? This can block other UI updates.
In general, you should make sure that it isn't modal, and that your workThread has a fairly low priority so that the UI can do its updating

Problem with threads and/or memory

I'm developing an application where there are 3 threads. One of them sends a request to the other, and if the 2nd can't answer it, it sends it to the 3rd (similar to CPU -> CACHE -> MEMORY). When i run the program with 1000-10.000 requests, no problem occurs. When i run it with 300.000-1.000.000 requests, it sometimes hangs. Is this a problem with the garbage collector, or should it be related to the threads mecanism.
(note: eache thread is in execution using a finite state machine)

i had been running the program inside Netbeans.
Running the jar using the command line outside
Netbeans i have no more problems... Does Netbeans use
it's own JVM?Depends how you set it up, but look under the options. There are settings for the compiler and jvm that it uses.

Null And " "

What is the difference between these two lines of codes?
String currentFile = null;
String currentFile = "";
Edited by: AMARSHI on Jul 10, 2008 7:07 AM

The reference variable itself, takes up the same amount of space, of course, as all references are the same size. Now, the object on the heap is a different story. With null there isn't one, of course (or if there is there is only one for the entire VM), and for the second a String object will be created in the String pool (once again, only one for the entire VM that every = "" assignment will use). But really, what difference does it make? If there is a difference, it is on the order of a few bytes (at max) for the entire VM, and if this is a concern, your probably doing something else greviously wrong. This miniscule difference should not concern you.
Edit: And "nulling" variables to "save" memory is also not something you should be concerned with. Either the variable will go out of scope and the object garbage collected anyway, or it's in constant use and so will not be taking up any extraneous heap space. If one of those is not the case, you are, once again, doing something greviously wrong.

And/or if statement in rtf templates.

Hi all,
I'm using XML Publisher 4.5.
I have created a word template file (rtf) for my reports. I need to be able to show some content in the template file by using and and/or if statement.
fx. <?if:doc_type='STANDARD'?> OR <?if:doc_type='DEFAULT'?>
How can I do this?
In advance thank you.
Best regards
Kenneth

Hi D,
Thank you for your answer.
I have seriously thought about that solution; but I don't think it's a smart way to do it.
If i do it like that, i need to copy the whole table and paste it inside the if statements.
I have two xml elements that I need to make the decisions on. POH_PO_TYPE & CP_RELEASE_NUM.
POH_PO_TYPE can be: STANDARD, RELEASE or BLANKET.
CP_RELEASE_NUM can be: '' or N
If POH_PO_TYPE is RELEASE AND CP_RELEASE_NUM is not ''
OR POH_PO_TYPE is STANDARD
OR POH_PO_TYPE is BLANKET AND CP_RELEASE_NUM is ''
THEN show table (which contains the whole PO).
It shall show the content of the PO in any of these cases.
BR Kenneth

I install window 8 and Unfortunatly all drive format. And all drive mix, now i have only 1 DRIVE C. I want Bit locker Drive's data Back

Last sunday i install a window 8 and this window format my all drive & make it 1 drive (DRIVE C). Before all of this i have 5 drive in different size with 1 Bitlocker protect drive.
So i try data recovery software to recover my data. i got back all my data without that ( bitlocker ) protected drive.
so please guys help me how can i get back data from bitlocker protected drives.
please please help me.

Hi,
I sorry for your experience, but there is no way to recovery the data encryped by BitLocker untill now.
BitLocker is designed to make the encrypted drive unrecoverable without the required authentication. When in recovery mode, the user needs the recovery password or recovery key to unlock the encrypted drive. Therefore, we highly recommend
that you store the recovery information in AD DS or in another safe location.
Please refer to the link below for the statement:
http://technet.microsoft.com/de-de/library/ee449438(v=ws.10).aspx#BKMK_RecoveryInfo
Roger Lu
TechNet Community Support

Open and cancelled Quote Report

Hi,
Can anyone give me the information for getting open and cancelled Quote Report?

I hope you are using reason for rejection for cancelling quotations. If that is the case, you can use transaction VA25 to view the list of quotations. Here you can filter on two columns status and reason for rejection to view the report as per your requirement.
Regards,
GSL.

RegisterTCPServer and ConnectToTCPServer

Similar Messages

Maybe you are looking for