Implement client-server communication using TCP
Implement client-server communication using TCP
Introduction:
TCP provides the service
of exchanging data directly between two network
hosts, whereas IP handles addressing and routing message
across one or more networks. In particular, TCP provides reliable, ordered
delivery of a stream of bytes from a program on one computer to another program
on another computer. TCP is the protocol that major Internet applications rely
on, applications such as the World
Wide Web, e-mail,
and file transfer.
TCP connection is managed
by an operating system through a programming interface that represents the
local end-point for communications, the Internet
socket. During the lifetime of a TCP connection it undergoes a series
of state changes:
- LISTEN :
In case of a server, waiting for a connection request from any remote
client.
- SYN-SENT :
waiting for the remote peer to send back a TCP segment with the SYN and
ACK flags set. (usually set by TCP clients)
- SYN-RECEIVED :
waiting for the remote peer to send back an acknowledgment after having
sent back a connection acknowledgment to the remote peer. (usually set by
TCP servers)
- ESTABLISHED :
the port is ready to receive/send data from/to the remote peer.
- FIN-WAIT-1
- FIN-WAIT-2
- CLOSE-WAIT
- CLOSING
- LAST-
- TIME-WAIT :
represents waiting for enough time to pass to be sure the remote peer
received the acknowledgment of its connection termination request.
According to RFC
793 a connection can stay in TIME-WAIT for a
maximum of four minutes.
- CLOSED
TCP
uses the notion of port
numbers to identify sending and receiving application
end-points on a host, or Internet
sockets. Each side of a TCP connection has an
associated 16-bit unsigned port number (0-65535) reserved by the sending or
receiving application. Arriving TCP data packets are identified as belonging to
a specific TCP connection by its sockets, that is, the combination of source host address, source port, destination host
address, and destination port. This means that a server computer can
provide several clients with several services simultaneously, as long as a
client takes care of initiating any simultaneous connections to one destination
port from different source ports.
TCP
Server:
import
java.net.*;
import
java.io.*;
public
class TCPServer {
public
static void main(String a[])
{
Socket s=null;
try
{
int serverPort=8117;
ServerSocket listenSocket=new
ServerSocket(serverPort);
while(true)
{
Socket clientSocket=listenSocket.accept();
Connection c=new Connection(clientSocket);
}
}
catch(IOException e)
{
System.out.println("Listen:"+e.getMessage()); }
}
}
class
Connection extends Thread {
DataInputStream in;
DataOutputStream out;
Socket clientSocket;
public Connection(Socket aClientSocket) {
try
{
clientSocket=aClientSocket;
in=new
DataInputStream(clientSocket.getInputStream());
out=new
DataOutputStream(clientSocket.getOutputStream());
this.start();
}
catch(IOException e)
{
System.out.println("Connection:"+e.getMessage());
}
}
public void run() {
try
{
String data=in.readUTF();
out.writeUTF(data);
}
catch(EOFException e)
{
System.out.println("EOF:"+e.getMessage()); }
catch(IOException e)
{
System.out.println("IO:"+e.getMessage()); }
finally
{
try
{
clientSocket.close();
}
catch(IOException e)
{
System.out.println("IO:"+e.getMessage()); }
}
}
}
TCP Client:
TCP Client:
import
java.net.*;
import
java.io.*;
public
class TCPClient {
public static void main (String
args[]) {
// arguments supply
message and hostname
Socket s = null;
try{
int
serverPort = 8117;
s = new
Socket(args[1], serverPort);
DataInputStream
in = new DataInputStream( s.getInputStream());
DataOutputStream
out =new DataOutputStream( s.getOutputStream());
out.writeUTF(args[0]); //
UTF is a string encoding see Sn. 4.4
String data
= in.readUTF(); // read a line of data from the stream
System.out.println("Received:
"+ data) ;
}catch (UnknownHostException
e){System.out.println("Socket:"+e.getMessage());
}catch (EOFException
e){System.out.println("EOF:"+e.getMessage());
}catch (IOException
e){System.out.println("readline:"+e.getMessage());
}finally {if(s!=null)
try {s.close();}catch (IOException
e){System.out.println("close:"+e.getMessage());}}
}
}
TCP: OUTPUT
C:\Documents and
Settings\cse4y>e:
E:\>cd Lab
E:\Lab>cd TCP
E:\Lab\TCP>javac
*.java
E:\Lab\TCP>java TCPServer
127.0.0.1
C:\Documents and
Settings\cse4y>e:
E:\>cd Lab
E:\Lab>cd TCP
E:\Lab\TCP>java
TCPClient hello 127.0.0.1
received;hello
Implement client-server communication using UDP
Implement client-server communication using UDP
Introduction:
With UDP, computer applications can
send messages, in this case referred to as datagrams,
to other hosts on an Internet
Protocol (IP) network without requiring prior communications
to set up special transmission channels or data paths. UDP uses a simple
transmission model without implicit hand-shaking for providing reliability, ordering, or data
integrity. UDP's stateless
nature is also useful for servers answering small queries from huge numbers of
clients. Unlike TCP,
UDP is compatible with packet broadcast
(sending to all on local network) and multicasting
(send to all subscribers).
UDP applications use datagram sockets to establish
host-to-host communications. A Datagram socket is a type of Internet
socket, which is the sending or receiving point for packet delivery
services.[1]
Each packet sent or received on a Datagram socket is individually addressed and
routed. Multiple packets sent from one machine to another may arrive in any
order and might not arrive at the receiving computer.UDP broadcasts sends are always enabled on a
Datagram Socket. In order to receive broadcast
packets a Datagram Socket must be bound to a more specific address.
An application binds a socket to its
endpoint of data transmission, which is a combination of an IP address
and a service port. A port is a software structure that is identified by the port number,
a 16 bit integer
value, allowing for port numbers between 0 and 65535.
Port numbers are
divided into three ranges:
·
Port numbers 0 through 1023 are used for common,
well-known services.
·
Port numbers 1024 through 49151 are the registered
ports
·
Ports 49152 through 65535 are dynamic ports that
are not officially used for any specific service, and can be used for any
purpose. They are also used as ephemeral
ports , from which software running on the host may randomly choose a port
in order to define itself.[2]
In effect, they are used as temporary ports primarily by clients when communicating with servers.
UDP Server:
import
java.net.*;
import
java.io.*;
public
class UDPServer {
public static void main(String args[]) {
DatagramSocket
aSocket = null;
try {
aSocket = new
DatagramSocket(8117);
byte[]
buffer = new byte[1000];
while(true)
{
DatagramPacket
request = new DatagramPacket(buffer, buffer.length);
aSocket.receive(request);
DatagramPacket
reply = new DatagramPacket(request.getData(), request.getLength(),
request.getAddress(),
request.getPort());
aSocket.send(reply);
}
}
catch (SocketException
e)
{
System.out.println("Socket:
" + e.getMessage());
}
catch (IOException e)
{
System.out.println("IO:
" + e.getMessage());
}
finally
{
if(aSocket
!= null) aSocket.close();
}
}
}
UDP Client:
import
java.net.*;
import
java.io.*;
public
class UDPClient {
public static void main(String args[]) {
DatagramSocket aSocket=null;
try
{
aSocket=new DatagramSocket();
byte[]m=args[0].getBytes();
InetAddress
aHost=InetAddress.getByName(args[1]);
int serverPort=8117;
DatagramPacket request=new DatagramPacket(m,args[0].length(),aHost,serverPort);
aSocket.send(request);
byte[] buffer=new byte[1000];
DatagramPacket reply=new
DatagramPacket(buffer,buffer.length);
aSocket.receive(reply);
System.out.println("Reply:"+new
String(reply.getData()));
}
catch(SocketException e)
{
System.out.println("Socket:"+e.getMessage()); }
catch(IOException e)
{
System.out.println("IO:"+e.getMessage()); }
finally
{
if(aSocket!=null)
aSocket.close();
}
}
}
UDP: OUTPUT
C:\Documents and
Settings\cse4y>e:
E:\>cd Lab
E:\Lab>cd UDP
E:\Lab\UDP>javac
*.java
E:\Lab\UDP>java
UDPServer 127.0.0.1
C:\Documents and
Settings\cse4y>e:
E:\>cd Lab
E:\Lab>cd UDP
E:\Lab\UDP>java
UDPClient hello 127.0.0.1
Reply:hello
Bulletin Board Implementation Using JSP
Bulletin Board Implementation Using JSP
Start.jsp:
<h2>Bulliten Board</h2>
<form
method="post" action="bb.jsp" >
Select
Group : <select name="grp">
<option value="grp1"/>Group-1
<option value="grp2"/>Group-2
</select><br><br>
UserName
: <input type="text" name="usr"
/><br><br>
Password
: <input type="password" name="pass"
/><br><br>
<input
type="button" value="Log In"
onclick="submit()"/>
</form>
bb.jsp:
<%@
page import="java.sql.*" %>
<%
Class.forName
("sun.jdbc.odbc.JdbcOdbcDriver");
String
grp=request.getParameter("grp");
String
usr=request.getParameter("usr");
String
pass=request.getParameter("pass");
try
{
Connection
con
=DriverManager.getConnection("jdbc:odbc:server","scott","tiger");
PreparedStatement
stmt=con.prepareStatement("select * from login where
usr='"+usr+"' and pass='"+pass+"' and
grp='"+grp+"'");
ResultSet
rs=stmt.executeQuery();
if(rs.next())
{ %>
<form
method="post" action="inbox.jsp" >
<input
type="hidden" name="flag"
value="<%=grp%>"/>
<input
type="button" value="Go to INBOX - - >"
onclick="submit()"/>
</form>
<%}
else
{
%>
Login
failed<br>
<form
method="post" action="start.jsp" >
<input type="button"
value="< - - Go Back" onclick="submit()"/>
</form>
<%
}
stmt.close();
}
catch(SQLException
se)
{
%>
Login
failed<br>
<form
method="post" action="start.jsp" >
<input type="button"
value="< - - Go Back" onclick="submit()"/>
</form>
<%
}
%>
Inbox.jsp:
<%
String
flag=request.getParameter("flag");
%>
<h2>INBOX</h2>
<form
method="post" action="read.jsp"
target="_blank">
<input
type="hidden" name="flag"
value="<%=flag%>"/>
<input
type="button" value="Read Messages" onclick="submit()"/>
</form><br>
<form
method="post" action="write.jsp"
target="_blank">
<input
type="hidden" name="flag"
value="<%=flag%>"/>
<input
type="button" value="Write Message"
onclick="submit()"/>
</form><br>
<form
method="post" action="start.jsp" >
<input
type="hidden" name="flag"
value="<%=flag%>"/>
<input type="button"
value="LogOut" onclick="submit()"/>
</form>
Read.jsp:
<%@
page import="java.sql.*" %>
<%
Class.forName
("sun.jdbc.odbc.JdbcOdbcDriver");
String
flag=request.getParameter("flag");
try
{
Connection
con
=DriverManager.getConnection("jdbc:odbc:server","scott","tiger");
PreparedStatement
stmt=con.prepareStatement("select * from "+flag+"");
ResultSet
rs=stmt.executeQuery();
%><h3>Messages</h3><br><%
while(rs.next())
{
out.println(rs.getString(1)+"<br>");
}
%>
<br><form
method="post" action="inbox.jsp" >
<input
type="hidden" name="flag"
value="<%=flag%>"/>
<input
type="button" value="< - - Go back to INBOX"
onclick="submit()"/>
</form>
<%
stmt.close();
}
catch(SQLException
se)
{
%>
Database
ERROR
<%
}
%>
Write.jsp:
<%
String
flag=request.getParameter("flag");
%>
<form
method="post" action="update.jsp" >
<input
type="hidden" name="flag"
value="<%=flag%>"/>
Enter
message here : <input type="text" name="msg"/><br>
<input
type="button" value="Write message to Database"
onclick="submit()"/>
</form>
Update.jsp:
<%@
page import="java.sql.*" %>
<%
Class.forName
("sun.jdbc.odbc.JdbcOdbcDriver");
String
flag=request.getParameter("flag");
String
msg=request.getParameter("msg");
try
{
Connection
con
=DriverManager.getConnection("jdbc:odbc:server","scott","tiger");
PreparedStatement
stmt=con.prepareStatement("insert into "+flag+"
values('"+msg+"')");
int
rs=stmt.executeUpdate();
if(rs == 1)
out.pintln("written successfully");
%>
<br><form
method="post" action="inbox.jsp" >
<input
type="hidden" name="flag"
value="<%=flag%>"/>
<input
type="button" value="< - - Go back to INBOX"
onclick="submit()"/>
</form>
<%
stmt.close();
}
catch(SQLException
se)
{
%>
Database
ERROR
<%
}
%>
Tables required
–
1.
Login (grp varchar2(20), usr
varchar2(20), pass varchar2(20));
2.
grp1 (msg varchar2(50));
3.
grp2 (msg varchar2(50));
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