Microcontroller socket programming with CVIwindows
Hello,
I am working on a project where a computer with CVIwindows GUI will be a server and my clients will be DS80C410 networked microcontrollers which has an inbuilt ethernet stack. The comm protocol will be TCP using socket programming. How do I develop socket programming on CVI to get the communication between microcontroller and CVI server?
Regards,
SR
I've attached an example c file for a multiclient TCP server from the shipping examples of CVI. CVI includes a TCP and a UDP library and you can add expanded functionality using the subroutine you mentioned. There's also some basic information on TCP programming in CVI in that document I linked in my first response.
Also you can get a 30 day trial of CVI here:
http://digital.ni.com/src.nsf/websearch/70C455BB6564DEC986257880005141F8?OpenDocument&node=node=2030...
I hope this answers your questions.
Product Support Engineer
National Instruments
Attachments:
MultiClientServer.c 20 KB
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at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:352)
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Problem in using socket streams with encryption and decryption
Hi,
I am developing a client/server program with encryption and decryption at both end. While sending a message from client it should be encrypted and at the receiving end(server) it should be decrypted and vice versa.
But while doing so i got a problem if i use both encryption and decryption at both ends. But If i use only encryption at one (only outputstream) and decryption at other end(only inputstream) there is no problem.
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serverSocketDemo.java
import java.io.*;
import java.net.*;
import java.security.*;
import java.security.spec.*;
import javax.crypto.*;
import javax.crypto.spec.*;
import java.util.*;
import java.util.zip.*;
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try
{ //server listening on port 2000
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int c;
while (true)
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catch(ConnectException e)
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catch(Exception e)
public static BufferedInputStream getNetInStream(InputStream in) throws Exception
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BufferedInputStream bin=new BufferedInputStream(new GZIPInputStream(cin));
return bin;
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import java.io.*;
import java.net.*;
import java.security.*;
import java.security.spec.*;
import javax.crypto.*;
import javax.crypto.spec.*;
import java.util.*;
import java.util.zip.*;
class clientSocketDemo
public static void main(String args[])
try
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out.flush();
out.close();
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catch(ConnectException e)
System.out.println("Connection is refused at remote host because the host is busy or no process is listening on that port");
catch(IOException e)
System.out.println("Connection disconnected");
catch(Exception e)
public static OutputStream getNetOutStream(OutputStream out) throws Exception
// register the provider that implements the algorithm
Provider sunJce = new com.sun.crypto.provider.SunJCE( );
Security.addProvider(sunJce);
// create a key
byte[] desKeyDataEnc = "This encryption can not be decrypted".getBytes();
DESKeySpec desKeySpecEnc = new DESKeySpec(desKeyDataEnc);
SecretKeyFactory keyFactoryEnc = SecretKeyFactory.getInstance("DES");
SecretKey desKeyEnc = keyFactoryEnc.generateSecret(desKeySpecEnc);
// use Data Encryption Standard
Cipher desEnc = Cipher.getInstance("DES");
desEnc.init(Cipher.ENCRYPT_MODE, desKeyEnc);
CipherOutputStream cout = new CipherOutputStream(out, desEnc);
OutputStream outstream=new BufferedOutputStream(new GZIPOutputStream(cout));
return outstream;
Here is client/server pair in which i use both encrypting outpustream and decrypting inputstream at both ends.
serverSocketDemo.java
import java.io.*;
import java.net.*;
import java.security.*;
import java.security.spec.*;
import javax.crypto.*;
import javax.crypto.spec.*;
import java.util.*;
import java.util.zip.*;
class serverSocketDemo
private Cipher desEnc,desDec;
serverSocketDemo()
try
// register the provider that implements the algorithm
Provider sunJce = new com.sun.crypto.provider.SunJCE( );
Security.addProvider(sunJce);
// create a key
byte[] desKeyData = "This encryption can not be decrypted".getBytes();
DESKeySpec desKeySpec = new DESKeySpec(desKeyData);
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
SecretKey desKey = keyFactory.generateSecret(desKeySpec);
desEnc = Cipher.getInstance("DES");
desEnc.init(Cipher.ENCRYPT_MODE, desKey);
desDec = Cipher.getInstance("DES");
desDec.init(Cipher.DECRYPT_MODE, desKey);
catch (javax.crypto.NoSuchPaddingException e)
System.out.println(e);
catch (java.security.NoSuchAlgorithmException e)
System.out.println(e);
catch (java.security.InvalidKeyException e)
System.out.println(e);
catch(Exception e)
System.out.println(e);
startProcess();
public void startProcess()
try
ServerSocket server=new ServerSocket(2000);
while (true)
final Socket theConnection=server.accept();
System.out.println("Connecting from local address : "+theConnection.getLocalAddress());
System.out.println("Connection request from : "+theConnection.getInetAddress());
Thread input=new Thread()
public void run()
try
//Input starts from here
Reader in=new InputStreamReader(new BufferedInputStream(new CipherInputStream(theConnection.getInputStream(), desDec)),"ASCII");
StringBuffer strbuf=new StringBuffer();
int c;
while (true)
c=in.read();
if(c=='\n'|| c==-1)
break;
strbuf.append((char)c);
String str=strbuf.toString();
System.out.println("Message from Client : "+str);
catch(Exception e)
System.out.println("Error caught inside input Thread : "+e);
input.start();
Thread output=new Thread()
public void run()
try
//Output starts from here
OutputStream out=new BufferedOutputStream(new CipherOutputStream(theConnection.getOutputStream(), desEnc));
System.out.println("it will not be printed");
out.write("You are Welcome\n".getBytes());
out.flush();
catch(Exception e)
System.out.println("Error caught inside output Thread : "+e);
output.start();
try
output.join();
input.join();
catch(Exception e)
theConnection.close();
catch(BindException e)
System.out.println("The Port is in use or u have no privilage on this port");
catch(ConnectException e)
System.out.println("Connection is refused at remote host because the host is busy or no process is listening on that port");
catch(IOException e)
System.out.println("Connection disconnected");
catch(Exception e)
public static void main(String args[])
serverSocketDemo server=new serverSocketDemo();
clientSocketDemo.java
import java.io.*;
import java.net.*;
import java.security.*;
import java.security.spec.*;
import javax.crypto.*;
import javax.crypto.spec.*;
import java.util.*;
import java.util.zip.*;
class clientSocketDemo
private Cipher desEnc,desDec;
clientSocketDemo()
try
// register the provider that implements the algorithm
Provider sunJce = new com.sun.crypto.provider.SunJCE( );
Security.addProvider(sunJce);
// create a key
byte[] desKeyData = "This encryption can not be decrypted".getBytes();
DESKeySpec desKeySpec = new DESKeySpec(desKeyData);
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
SecretKey desKey = keyFactory.generateSecret(desKeySpec);
desEnc = Cipher.getInstance("DES");
desDec = Cipher.getInstance("DES");
desEnc.init(Cipher.ENCRYPT_MODE, desKey);
desDec.init(Cipher.DECRYPT_MODE, desKey);
catch (javax.crypto.NoSuchPaddingException e)
System.out.println(e);
catch (java.security.NoSuchAlgorithmException e)
System.out.println(e);
catch (java.security.InvalidKeyException e)
System.out.println(e);
catch(Exception e)
System.out.println(e);
startProcess();
public void startProcess()
try
final Socket theConnection=new Socket("localhost",2000);
System.out.println("Connecting from local address : "+theConnection.getLocalAddress());
System.out.println("Connecting to : "+theConnection.getInetAddress());
Thread output=new Thread()
public void run()
try
//Output starts from here
OutputStream out=new BufferedOutputStream(new CipherOutputStream(theConnection.getOutputStream(), desEnc));
out.write("Please Welcome me\n".getBytes());
out.flush();
catch(Exception e)
System.out.println("Error caught inside output thread : "+e);
output.start();
Thread input=new Thread()
public void run()
try
//Input starts from here
Reader in=new InputStreamReader(new BufferedInputStream(new CipherInputStream(theConnection.getInputStream(), desDec)),"ASCII");
System.out.println("it will not be printed");
StringBuffer strbuf=new StringBuffer();
int c;
while (true)
c=in.read();
if(c=='\n' || c==-1)
break;
strbuf.append((char)c);
String str=strbuf.toString();
System.out.println("Message from Server : "+str);
catch(Exception e)
System.out.println("Error caught inside input Thread : "+e);
input.start();
try
output.join();
input.join();
catch(Exception e)
theConnection.close();
catch(BindException e)
System.out.println("The Port is in use or u have no privilage on this port");
catch(ConnectException e)
System.out.println("Connection is refused at remote host because the host is busy or no process is listening on that port");
catch(IOException e)
System.out.println("Connection disconnected");
catch(Exception e)
public static void main(String args[])
clientSocketDemo client=new clientSocketDemo();
**** I know that the CInput tries to read some header stuff thats why i used two threads for input and output.
Waiting for the reply.
Thank you.Do not ever post your code unless requested to. It is very annoying.
Try testing what key is being used. Just to test this out, build a copy of your program and loop the input and outputs together. Have them print the data stream onto the screen or a text file. Compare the 1st Output and the 2nd Output and the 1st Input with the 2nd Input and then do a static test of the chipher with sample data (same data which was outputted), then do another cipher test with the ciphertext created by the first test.
Everything should match - if it does not then follow the steps below.
Case 1: IO Loops do not match
Case 2: IO Loops match, but ciphertext 1st run does not match loop
Case 3: IO Loops match, 1st ciphertext 1st run matches, but 2nd run does not
Case 4: IO Loops match, both chiphertext runs do not match anything
Case 5: Ciphertext runs do not match eachother when decrypted correctly (outside of the test program)
Problems associated with the cases above:
Case 1: Private Key is changing on either side (likely the sender - output channel)
Case 2: Public Key is changing on either side (likely the sender - output channel)
Case 3: Private Key changed on receiver - input channel
Case 4: PKI failure, causing private key and public key mismatch only after a good combination was used
Case 5: Same as Case 4 -
File descriptor leak in socket programming
We have a complex socket programming client package in java using java.nio (Selectors, Selectable channel).
We use the package to connect to a server.
Whenever the server is down, it tries to reconnect to the server again at regular intervals.
In that case, the number of open file descriptors build up with each try. I am able to cofirm this using "pfile <pid>" command.
But, it looks like we are closing the channels, selectors and the sockets properly when it fails to connect to the server.
So we are unable to find the coding that causes the issue.
We run this program in solaris.
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Thanks.Don't close the selector. There is a selector leak. Just close the socket channel. As this is a client you should then also call selector.selctNow() to have the close take final effect. Otherwise there is also a socket leak.
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Network and socket programming in python
i want to learn network and socket programming but i would like to do this in python.Reason behind this is that python is very simple and the only language i know .
anybody can suggest me which book should i pick.
the book should have following specification--
1)not tedious to follow
2)lots of example
3)starts with some networking stuff and then get into codes
thanks in advance with regards.hmm. well, your requirements are almost contradictory.
Not sure about books, except maybe dusty's.
Most python books cover at least some network programming (unless the book is topic specific).
I use lots of python-twisted at work. I mean ALOT. I wouldn't recommend it to someone looking for non-tedious though! I also like gevent/eventlet (esp. the async socket wrappers).
EDIT: Wow. My post wasn't really helpful at all. Sorry!
Last edited by cactus (2010-09-04 09:16:54) -
Socket programming usin nio package
hello frens i m new to socket programming
i come to know that nio packaage provides more sophisticated and efficient API to deal with socket programming issue
I need to know where i can get tutorial about socket programming using nio pacakageTry google
http://www.google.co.uk/search?q=java+nio+tutorial -
Hi,
I have been given a new project whereby I have to:
1) Write a class with a method that takes as an argument an xml document, communicate s with a SOAP server and return the SOAPs response (in this case a ResponseWrapper object).
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The reason for this being is that it can be uploaded to a server, allowing a pearl program to send the XML to the Daemon, have this contact the SOAP server and then return the SOAPs response back to the pearl program.
I am aware that this sounds unnecessarily complicated but it does have to be implemented this way.
I have written the class and it successfully communicates with the SOAP server and returns a response, but have no idea how to implement it as a Daemon and have had no experience with socket programming.
Could anyone point me to a tutorial or give me some pointers in how to get started?
Thanks,It was an option to use a Web Service, but I was told
that due to security issues it would take to long to
write all the necessary checks and interceptors
(which I know how to do), so I should implement it
this way (which I don't know how to do); since it is
sitting behind the firewall it would not be
accessible for spoofing.Huh? You realize that tons of very sensitive information is transmitted all over the internet using Web Services right?
I have had no experience
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May I use socket for 3G networks?
I use the demo provided by the WTK2.5-Beta(NetworkDemo), it works well in the simulator. However, when I download the program to the mobile phone, it seems that the mobile phone that runs ServerSocket cannot create the socket ... all the 2 handsets use a 3G SIM card provided by a Hong Kong ISP smartTone ... What can I do?
Please help~ provide any web page of codes, thanks very much!1. We want to create a socket connection which can
remain open and live for ever till it is closed. Is
this possible in java socket programming?Yes, but it isn't practical in the real networking world. So your code had better be prepared to deal with network failures.
2. I am just wondering in order to communicate with
the third party over the socket connection, does this
other party requires to run something specific on
their end? I am not able to understand how will my
java code communicate with their server otherwise.It has nothing to do with java. Sockets send and recieve messages. The applications at either end, regardless of the language that they are written in, must handle those messages.
3. Can we send and receive data over the socket
created and also is their specific format for the
data? Yes.
Can we send files of data over this connection?Yes. (Although I don't know why you would need to do that if you are doing credit card auths.)
It would be great if someone can comment on these
questions and also if possible please provide some
code that can create socket connection.The tutorial.....
http://java.sun.com/docs/books/tutorial/networking/sockets/index.html -
First Very Simple Socket Program
Hello,
I am learning about Sockets and ServerSockets and how I can use the. I am trying to make the simplest server/client program possible just for my understanding before I go deper into it. I have written two programs. theserver.java and theclient.java the sere code looks like this....
import java.net.*;
import java.io.*;
import java.util.*;
public class theserver
public static void main(String[] args)
{ // IOReader r = new IOReader();
int prt = 3333;
BufferedReader in;
PrintWriter out;
ServerSocket serverSocket;
Socket clientSocket = null;
try{
serverSocket = new ServerSocket(prt); // creates the socket looking on prt (3333)
System.out.println("The Server is now running...");
while(true)
clientSocket = serverSocket.accept(); // accepts the connenction
clientSocket.getKeepAlive(); // keeps the connection alive
out = new PrintWriter(clientSocket.getOutputStream(),true);
in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
if(in.ready())
System.out.println(in.readLine()); // print it
catch (IOException e) {
System.out.println("Accept failed:"+prt);
}and the client looks like this
import java.net.*;
import java.io.*;
public class theclient
public static void main(String[] args)
BufferedReader in;
PrintWriter out;
IOReader r = new IOReader();
PrintWriter sender;
Socket sock;
try{
sock = new Socket("linuxcomp",3333); // creates a new connection with the server.
sock.setKeepAlive(true); // keeps the connection alive
System.out.println("Socket is connected"); // confirms socket is connected.
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String bob = r.readS();
out = new PrintWriter(sock.getOutputStream(),true);
out.print(bob); // write bob to the server
catch(IOException e)
System.out.println("The socket is now disconnected..");
}If you notice in the code I use a class I made called IOReader. All that class is, is a buffered reader for my System.in. (just makes it easier for me)
Ok now for my question:
When I run this program I run the server first then the client. I type "hello" into my system.in but on my server side, it prints "null" I can't figure out what I am doing wrong, if I am not converting correctly, or if the message is not ever being sent. I tried putting a while(in.read()) { System.out.println("whatever") } it never reaches a point where in.ready() == true. Kinda of agrivating. Because I am very new to sockets, I wanna aks if there is somthing wrong with my code, or if I am going about this process completely wrong. Thank you to how ever helps me,
CobbwebAn example of Creating a Client Socket (Java socket programming tutorial)
try {
InetAddress addr = InetAddress.getByName("hotdir.biz");
int port = 80;
// This constructor will block until the connection succeeds
Socket socket = new Socket(addr, port);
} catch (UnknownHostException e) {
} catch (IOException e) {
// Create a socket with a timeout
try {
InetAddress addr = InetAddress.getByName("hotdir.biz");
int port = 80;
SocketAddress sockaddr = new InetSocketAddress(addr, port);
// Create an unbound socket
Socket sock = new Socket();
// This method will block no more than timeoutMs.
// If the timeout occurs, SocketTimeoutException is thrown.
int timeoutMs = 2000; // 2 seconds
sock.connect(sockaddr, timeoutMs);
} catch (UnknownHostException e) {
} catch (SocketTimeoutException e) {
} catch (IOException e) {
}See socket tutorial here http://www.developerzone.biz/index.php?option=com_content&task=view&id=94&Itemid=36 -
Socket Programming-Not getting response from server.
Hi,
I am trying to communicate with server using java socket programming, I am getting the response for first two times third time when I am trying to write some thing I am not getting any response from the server,
I am writing to migrate the vb code to Java the vb is using a c++ dll to communicate with the server and we tried accessing the dll from java using JNI then it is working fine, this dll is dependent on windows so we want to avoid the dependency with windows that is why we are going for socket programming, Please help on this.Hi,
I am writing the data in forms of string
like
Socket sockt = new Socket(ipAddress, portNo);
out= new DataOutputStream(sockt.getOutputStream());
in = new DataInputStream(sockt.getInputStream());
out.writeBytes("Serv");
out.writeBytes("Serv,32");
out.writeBytes("home,serv32,run.prg,sucess");
these are the strings to communicate with server.
I am trying to read the same
StringBuffer buf = new StringBuffer();
byte b = '\0';
try {
while ((b = in.readByte()) != '\0')
char ch = (char) b;
buf.append(ch);
} catch (Exception e) {
System.out.println(e.getStackTrace());
we are getting the response for the first two strings, but for the third string it is getting stucked for some time and returing some junk values like '???' we are sending the same string using JNI and it is working.
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