Jaipur Engineering College & Research Centre, Jaipur

Manual
Of
TCP/IP Programming Lab (7CP8)

Session 2007-2008

Computer Engineering Department

Prepared By:
Mahesh Jangid

cc

Exercise No. 1

AIM: Study of Data Communication System, Connectionless and connection oriented service, programming with TCP and UDP.
Theory: -
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Networking Basics
• computers running on the Internet communicate to each other using either Transmission Control (TCP) or the User Datagram (UDP) protocol
• when we write Java programs that communicate over the network, we are programming at the application layer
• however, to decide which Java classes our programs should use, we need to understand how TCP and UDP differ

UDP (User Datagram Protocol)
• connectionless - sends independent packets of data, called datagram, from one computer to another with no guarantees about arrival
• each time a datagram is sent, the local and receiving socket address need to be sent as well

TCP (Transmission Control Protocol)
• connection-oriented - provides a reliable flow of data between two computers _ data sent from one end of the connection gets to the other end in the same order
• in order to communicate using TCP protocol, a connection must first be established between the pair of sockets
• once two sockets have been connected, they can be used to transmit data in both (or either one of the) directions

UDP vs. TCP: Which Protocol to Use?
• Overhead
_ UDP - every time a datagram is sent, the local and receiving socket address need to be sent along with it
_ TCP - a connection must be established before communications between the pair of sockets start (i.e. there is a connection setup time in TCP)
• Packet Size
_ UDP - there is a size limit of 64 kilobytes per datagram
_ TCP - there is no limit; the pair of sockets behaves like streams
• Reliability
_ UDP - there is no guarantee that the sent datagram will be received in the same order by the receiving socket
_ TCP - it is guaranteed that the sent packets will be received in the order in which they were sent

UDP vs. TCP: Which Protocol to Use?
• TCP - useful when indefinite amount of data of need to be transferred ‘in order’ and reliably
_ otherwise, we end up with jumbled files or invalid information
_ examples: HTTP, ftp, telnet, …
• UDP - useful when data transfer should not be slowed down by the extra overhead of the reliable connection
_ examples: real-time applications
_ e.g. consider a clock server that sends the current time to its client
_ if the client misses a packet, it doesn't make sense to resend it because the time will be incorrect when the client receives it on the second try
_ the reliability of TCP is unnecessary -it might cause performance degradation and hinder the usefulness of the service

Some Internet Application and their Underlying Transport Protocols
Application Application Protocol Transport Protocol e-mail smtp TCP remote access telnet TCP
Web http TCP file transfer ftp TCP domain name service DNS TCP or UDP internet telephony proprietary UDP

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What is a Port?
• generally, a computer has a single physical connection to the network
_ this connection is identified by the computer’s 32-bit IP address
_ all data destined for a particular computer arrives through this connection
• TCP and UDP use ports to identify a particular process/application
_ port = abstract destination point at a particular host
_ each port is identified by a positive 16-bit number, in the range 0 - 65,535
_ port numbers 0 - 1023 are reserved for well-known services (HTTP - 80, telnet - 23)

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What is a Socket?
• socket = basic abstraction for network communication
_ “end-point of communication” uniquely identified with IP address and port
_ example: Socket MyClient = new Socket("Machine name", PortNumber);
_ gives a file-system like abstraction to the capabilities of the network
_ two end-points communicate by “writing” into and “reading” out of socket
_ there are two types of transport via sockets
_ reliable, byte-stream oriented
_ unreliable datagram

Socket Programming with TCP
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Socket Programming with UDP
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Exercise No. 2

AIM: Write a program to get the IP address by giving hostname of any node in network & vice versa.

Theory: - An IP address (Internet Protocol address) is a unique address that certain electronic devices use in order to identify and communicate with each other on a computer network utilizing the Internet Protocol standard (IP)—in simpler terms, a computer address. The IP address acts as a locator for one IP device to find another and interact with it.

2 Package java.net Provides the classes for implementing networking applications. InetAddress class represents an Internet Protocol (IP) address. An instance of an InetAddress consists of an IP address and possibly its corresponding host name.

3 Methods Used:

1. public static InetAddress getByName(String host) : It determines the IP address of a host, given the host's name. 2. public static InetAddress getLocalHost() : It returns the IP address of Localhost. 3. public static InetAddress[] getAllByName(String host) : Given the name of a host, returns an array of its IP addresses, based on the configured name service on the system.

Algorithm: -
Step 1: Import java.net package.
Step2: Define a class and a main () method.
Step3: Creates an object of intaddress class and by calling getlocalhost() method.
Step4. Get the address of rediff.com by getbyname() method and print.
Step5: Creates an array of object of intaddress class that contains all addresses related to one server and print the object.
Output: -
Local address-192.168.1.15
Rediff.com-202.56.25.1
Yahoo.com-201.154.25.36, 203.65.65.5

Viva Questions: - 1. What are logical address and physical address? 2. What is alias name? 3. Why we use alias name instead of IP address.

Exercise No. 3

AIM: Write a program that works as an echo server and echo client.
Theory: -
ServerSocket class implements server sockets. A server socket waits for requests to come in over the network. It performs some operation based on that request, and then possibly returns a result to the requester.
Socket class implements client sockets (also called just "sockets"). A socket is an endpoint for communication between two machines.
Methods Used: 1. public Socket accept()

Listens for a connection to be made to this socket and accepts it. The method blocks until a connection is made.A new Socket s is created.
Package java.net provides the classes for implementing networking applications.
Package java.io provides for system input and output through data streams, serialization and the file system.

Algorithm: -
Server
Step 1: Import java.net package.
Step2: Define a class and a main () method.
Step3: Creates an object of serversocket class.
Step4. Call the accept() method that can listen any request.
Step5: if the client send request than Print “client is connected” Otherwise Print “client is not connected”

Client
Step 1: Import java.net package.
Step2: Define a class and a main () method.
Step3: Creates an object of socket class with ip address of server and port no.
Step4 if the request is accepted than Print “sever is connected” Otherwise Print “server is not connected”

Output: - Server: - Client is connected. Client: - Server is connected.

Viva Questions: - 1. What are server and client? 2. What is serversocket and socket class? 3. What are the differences b/w serversocket and socket?

Exercise No. 4

AIM: (A). Write a Server program that get string from the client side and capitalized it and send it back to the client. (B). Write a Client program that send String to the Server and get capitalized String.
Theory: -
ServerSocket class implements server sockets. A server socket waits for requests to come in over the network. It performs some operation based on that request, and then possibly returns a result to the requester. Socket class implements client sockets (also called just "sockets"). A socket is an endpoint for communication between two machines.

Methods Used: 1. public Socket accept() Listens for a connection to be made to this socket and accepts it. The method blocks until a connection is made.A new Socket s is created.

2. public InputStream getInputStream() Returns an input stream for this socket. If this socket has an associated channel then the resulting input stream delegates all of its operations to the channel. If the channel is in non-blocking mode then the input stream's read operations will throw an IllegalBlockingModeException.

3. public OutputStream getOutputStream() Returns an output stream for this socket. If this socket has an associated channel then the resulting output stream delegates all of its operations to the channel. If the channel is in non-blocking mode then the output stream's write operations will throw an IllegalBlockingModeException.

Package java.net provides the classes for implementing networking applications.
Package java.io provides for system input and output through data streams, serialization and the file system.

Algorithm: -
Server
Step 1: Import java.net package.
Step2: Define a class and a main () method.
Step3: Create an object of serversocket class with a port no.
Step4. Call the accept () method that can listen a request from the client.
Step5: Create an object of BufferedReader class that gets input from inputsteam of socket class.
Step6: Create an object of DataOutputSteam class that is used to send data to the socket.
Step7: To change the case of received string from client, use toUpperCase() method.
Step8: Send modified string, using writeBytes method.

Client:-
Step 1: Import java.net package.
Step2: Define a class and a main () method.
Step3: Create an object of socket class with ip address of sever and a port no.
Step4: Create an object of BufferedReader class that gets input from client.
Step5: Create an object of DataOutputSteam class that is used to send data to the socket.
Step6: Send modified string, using writeBytes method.
Step7: Create another object of BufferedReader class that gets input from server.
Step8: Print the modified string.

Output: - Server: - Received: jecrc Send: JECRC Client: - Send:jecrc Received: JECRC

Viva Questions: - 1. What is port no? 2. What is socket? How does it different from port no? 3.What are the differences b/w serversocket and socket?

Exercise No. 5

AIM: (A). Write a Server program that works as Chat Server. (B). Write a Client program that works as Chat Client.

Algorithm: -
Server
Step 1: Import java.net package.
Step2: Define a class and a main () method.
Step3: Create an object of serversocket class with a port no.
Step4. Call the accept () method that can listen a request from the client.
Step5: Create an object of BufferedReader class that gets input from inputsteam of socket class.
Step6: Create another object of BufferedReader class that gets input from command prompt.
Step7: Create an object of DataOutputSteam class that is used to send data to the socket.
Step8: Print the string that gets from the client and also string thatsend to client.

Client:-
Step 1: Import java.net package.
Step2: Define a class and a main () method.
Step3: Create an object of socket class with ip address of sever and a port no.
Step4: Create an object of BufferedReader class that gets input from client’s dos.
Step5: Create an object of DataOutputSteam class that is used to send data to the socket.
Step6:
Step7: Create another object of BufferedReader class that gets input from server.
Step8: Print the string that gets from sever..

Output: - Server: - Server: hi Client: hello Client: - Server: hello Client: hi

Viva Questions: - 1. How chat sever works? 2. What are serversocket and socket class? 3. What are the differences b/w serversocket and socket?

Exercise No. 6

AIM: (A). Write a Server program that sends Time and Day to Client. (B). Write a Client program that receives Time and Day from Server.

Algorithm: -
Server
Step 1: Import java.net package.
Step2: Define a class and a main () method.
Step3: Create an object of serversocket class with a port no.
Step4. Call the accept () method that can listen a request from the client.
Step5: Create an object of Date class that show time or date of server pc.
Step6: Whenever a server accepts a request from client, it sends time and date to client.

Client:-
Step 1: Import java.net package.
Step2: Define a class and a main () method.
Step3: Create an object of socket class with ip address of sever and a port no.
Step4: Create an object of BufferedReader class that gets date and time from server.
Step5: Print the date and time, which send by the server.

Output: - Client: - Time : 2.52.56 Date :14/08/2007

Viva Questions: - 1. How date timeserver works? 2. What are serversocket and socket class? 3. What are the differences b/w serversocket and socket?

Exercise No. 7

AIM: (A). Write a Server program, which handles multiple clients’ requests. (B). Write a Client program, which takes input from client and sends it to server.

Algorithm: -
Server
Step 1: Import java.net package.
Step2: Define a class and a main () method in this class and another class that handling threads this class extend thread class.
Step3: Create an object of server socket class with a port no.
Step4: Call the accept () method that can listen a request from the client.
Step5: After receiving a request from client, create a constructor of thread class and pass parameter to that constructor.
Step6: Thread class overrides the run method of java thread class.

Client:-
Step 1: Import java.net package.
Step2: Define a class and a main() method.
Step3: Create an object of socket class with ip address of sever and a port no.
Step4: Create an object of BufferedReader class that gets date and time from server.
Step5: Print the date and time, which send by the server.

Output: - Client: - Time: 2.52.56 Date: 14/08/2007

Viva Questions: - 1. How date timeserver works? 2. What are serversocket and socket class? 3. What are the differences b/w serversocket and socket?