linux TCP socket program for java client to c server


T

TsanChung

I want to make a java TCP socket client to communicate with a TCP
server socket on linux.
Are there some sample C unix server and java client socket programs
available?

The Richard Stevens' "Unix network programming" book described a TCP
server (tcpcliserv04.c) and client (tcpcli04.c). I compiled and
executed them successfully as follows:

$ tcpcliserv04 &
$ tcpcli04 172.20.11.211
12
12
90
90


I start to write a java socket client program but it fail to connect.
Please help.
Thanks.

import java.net.*;
import java.io.*;

public class socketClientWriteRead
{
public static final int PORT = 9877;

public static void main(String[] args) throws IOException
{
String host = "";
if (args.length >= 1)
host = args[0];
//String host = args[0];
byte[] bytes = new byte[1024];
int len = 0;
int ch = 0;
Socket sock = new Socket(host, PORT);
InputStream in = sock.getInputStream();
OutputStream out = sock.getOutputStream();
System.out.println( "Hello World!" );

while (len > 0 || ch != -1) {
if ((len = in.read(bytes)) > 0)
System.out.write(bytes, 0, len);

if ((ch = System.in.read()) != -1)
out.write(ch);
} // while
in.close();
out.close();
}
}

$ java socketClientWriteRead 172.20.11.66
Exception in thread "main" java.net.ConnectException: Connection
refused
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:
333)
at
java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
at java.net.Socket.connect(Socket.java:518)
at java.net.Socket.connect(Socket.java:468)
at java.net.Socket.<init>(Socket.java:365)
at java.net.Socket.<init>(Socket.java:179)
at socketClientWriteRead.main(socketClientWriteRead.java:18)
 
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N

Nigel Wade

TsanChung said:
I want to make a java TCP socket client to communicate with a TCP
server socket on linux.
Are there some sample C unix server and java client socket programs
available?

The Richard Stevens' "Unix network programming" book described a TCP
server (tcpcliserv04.c) and client (tcpcli04.c). I compiled and
executed them successfully as follows:

$ tcpcliserv04 &
$ tcpcli04 172.20.11.211 [snip]

$ java socketClientWriteRead 172.20.11.66

Did you mean to connect to a different server with the Java client?

The error below means that the server refused the connection, usually because
there is nothing listening on the requested port.
 
A

Andrew Gabriel

I want to make a java TCP socket client to communicate with a TCP
server socket on linux.
Are there some sample C unix server and java client socket programs
available?

The Richard Stevens' "Unix network programming" book described a TCP
server (tcpcliserv04.c) and client (tcpcli04.c). I compiled and
executed them successfully as follows:

$ tcpcliserv04 &
$ tcpcli04 172.20.11.211
12
12
90
90


I start to write a java socket client program but it fail to connect.
public static final int PORT = 9877;

Can you "telnet 172.20.11.211 9877" ?

Did you remember to pass the port number in network byte order
in the bind() call on the server?
 
T

TsanChung

TsanChung said:
I want to make a java TCP socket client to communicate with a TCP
server socket on linux.
Are there some sample C unix server and java client socket programs
available?
The Richard Stevens' "Unix network programming" book described a TCP
server (tcpcliserv04.c) and client (tcpcli04.c).  I compiled and
executed them successfully as follows:
$ tcpcliserv04 &
$ tcpcli04  172.20.11.211 [snip]

$ java socketClientWriteRead 172.20.11.66

Did you mean to connect to a different server with the Java client?

The error below means that the server refused the connection, usually because
there is nothing listening on the requested port.
Exception in thread "main" java.net.ConnectException: Connection
refused
        at java.net.PlainSocketImpl.socketConnect(Native Method)
        at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:
333)
        at
java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
        at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
        at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
        at java.net.Socket.connect(Socket.java:518)
        at java.net.Socket.connect(Socket.java:468)
        at java.net.Socket.<init>(Socket.java:365)
        at java.net.Socket.<init>(Socket.java:179)
        at socketClientWriteRead.main(socketClientWriteRead.java:18)

It is a typo. It should be:
java socketClientWriteRead 172.20.11.211
Thanks.
 
R

raxit

I want to make a java TCP socket client to communicate with a TCP
server socket on linux.
Are there some sample C unix server and java client socket programs
available?

The Richard Stevens' "Unix network programming" book described a TCP
server (tcpcliserv04.c) and client (tcpcli04.c).  I compiled and
executed them successfully as follows:

$ tcpcliserv04 &
$ tcpcli04  172.20.11.211
12
12
90
90

I start to write a java socket client program but it fail to connect.
Please help.
Thanks.

import java.net.*;
import java.io.*;

public class socketClientWriteRead
{
   public static final int PORT = 9877;

   public static void main(String[] args) throws IOException
   {
         String host = "";
         if (args.length >= 1)
             host = args[0];
             //String host = args[0];
         byte[] bytes = new byte[1024];
         int len = 0;
       int ch = 0;
         Socket sock = new Socket(host, PORT);
         InputStream in = sock.getInputStream();
         OutputStream out = sock.getOutputStream();
       System.out.println( "Hello World!" );

         while (len > 0 || ch != -1) {
            if ((len = in.read(bytes)) > 0)
               System.out.write(bytes, 0, len);

          if ((ch = System.in.read()) != -1)
             out.write(ch);
         } // while
         in.close();
       out.close();
    }

}

$ java socketClientWriteRead 172.20.11.66
Exception in thread "main" java.net.ConnectException: Connection
refused
        at java.net.PlainSocketImpl.socketConnect(Native Method)
        at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:
333)
        at
java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
        at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
        at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
        at java.net.Socket.connect(Socket.java:518)
        at java.net.Socket.connect(Socket.java:468)
        at java.net.Socket.<init>(Socket.java:365)
        at java.net.Socket.<init>(Socket.java:179)
        at socketClientWriteRead.main(socketClientWriteRead.java:18)


On which port your server is listening ?
On which port your client is trying to connect to server ?
 
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A

Antoninus Twink

$ tcpcliserv04 & [snip]
I start to write a java socket client program but it fail to connect.

Your client program seems fine (it's working OK here at least) - as long
as the server (actually called tcpserv04 in the books's provided source
code?) is still alive then you shouldn't have any problem connecting.
 
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