ITEC 350 Homework 2

Socket Programming

API available to programs

• Application Programming Interface (API) to TCP & UDP– “Sockets”– Two Modes:

• Datagram (DGRAM)• Stream (INET)

– A socket is defined by an IP address and a port number

TCP | UDP

Transport Layer

Stream Dgram

Application Program

Socket Programming – HW02• Writing programs in Java can give students

great insight into sockets, IP addresses, ports, etc.

• If you have had ITEC 120/220– Then you know all about java stream io

(BufferedReader, BufferedWriter)– All you need is java.net package

• If you have _not_ had ITEC 120/220 – you may use a programming language like C, C++,

etc.– Or, if you have had no programming language that

supports sockets, come see me in office hours.

java.net• The “real” .net … not that other M$.NET• Packages: what Java calls collections of classes• .net is a package – containing classes:

– Socket, ServerSocket for TCP streams– DatagramSocket for UDP datagrams

• We will implement the following flowcharts

Client

Open a connection on port 4444

Wait for user to type something

Send client text to server

Wait for server response

Echo server response to cmdwin for client

If user types only CR, exitelse

ServerCreate a ServerSocket object for port 4444

Using ServerSocket.accept, wait for a client to open a connection

When a client opens a connection, the accept method has returned a copy of the client socket. Create a BufferedReader for this object.Using getOutputStream() method createPrintWriter object.

Wait for client to type something

Echo client text to cmdwin for server. Accept server response from keyboard

Send server text over socket to client

ServerSocket classConstructor Summary

ServerSocket() Creates an unbound server socket.

ServerSocket(int port) Creates a server socket on a specified port.

ServerSocket(int port, int backlog) Creates a server socket and binds it to the specified local port number, with the specified backlog.

ServerSocket(int port, int backlog, InetAddress bindAddr) Create a server with the specified port, listen backlog, and local IP address to bind to.

Socket ClassConstructor Summarypublic Socket()

Creates an unconnected socket, with the system-default type of SocketImpl.

public Socket(InetAddress address, int port) Creates a stream socket and connects it to the specified port number at

the specified IP address.public

  Socket(InetAddress host, int port, boolean stream) Deprecated. Use DatagramSocket instead for UDP transport.

public Socket(InetAddress address, int port, InetAddress localAddr, int localPort)

Creates a socket and connects it to the specified remote address on the specified remote port.

Pro-tecte

d

Socket(SocketImpl impl) Creates an unconnected Socket with a user-specified SocketImpl.

public Socket(String host, int port)

Creates a stream socket and connects it to the specified port number on the named host.

public  Socket(String host, int port, boolean stream)

Deprecated. Use DatagramSocket instead for UDP transport.public

  Socket(String host, int port, InetAddress localAddr, int localPort) Creates a socket and connects it to the specified remote host on the

specified remote port.

DatagramSocket classConstructor Summary

 publicDatagramSocket()

Constructs a datagram socket and binds it to any available port on the local host machine.

protected DatagramSocket(DatagramSocketImpl impl)

Creates an unbound datagram socket with the specified DatagramSocketImpl.

 public  DatagramSocket(int port)

Constructs a datagram socket and binds it to the specified port on the local host machine.

  publicDatagramSocket(int port, InetAddress laddr)

Creates a datagram socket, bound to the specified local address.

  publicDatagramSocket(SocketAddress bindaddr)

Creates a datagram socket, bound to the specified local socket address.

Related classesConstructor Summary – InetSocketAddress (subclass of

SocketAddress)

InetSocketAddress(InetAddress addr, int port)  Creates a socket address from an IP address and a port number.

InetSocketAddress(int port) Creates a socket address where the IP address is the wildcard address and the port number a specified value.

InetSocketAddress(String hostname, int port) Creates a socket address from a hostname and a port number.

InetSocketAddresspublic InetSocketAddress(int port) Creates a socket address where the IP address is the wildcard

address and the port number a specified value. A valid port value is between 0 and 65535. A port number of zero will let the system pick up an ephemeral port in a bind operation.

Note• this is *NOT* the standard Echo

server that is widely found on the web.

• You must have echo going in both directions.

• Java Programming, but as a last resort C or C++

• If you only know C, C++ – Let me know via email

Submission

• Save your source codes and a ReadMe.doc file to RU03 folder of your dropbox

• The ReadMe.doc file must include:– Your name– File names of your source codes and

descriptions of each files.– Executing Instruction– Length: Less than 3 pages