The document discusses Java socket programming, explaining the structure and function of internet sockets, both client and server types. It outlines the layers of internet communication, including protocols and data exchange methods, while referencing specific Java packages and classes for implementation. Additionally, it humorously critiques the efficacy of internet traffic and mentions the theoretical significance of randomness in communication.

1. Networking with Java
Socket programming
Presented by
ganesh kavhar

2. The Interweb thing Al Gore
invented…
 Internet is a network of networks.
 The Internet is really people communicating.
 Application layers 7, 6 :
 email, HTTP, FTP, Telnet, file 'sharing', streaming
media, VoIP
 remote access: VPN
 Session layer 5: connections. e.g. sockets
 Transport layer 4: TCP, UDP
 Network layer 3: IP, the Internet
 Link layer 2, 1: NICs, device drivers, magic.

3. Internet traffic
 10% YouTube HTTP
 36% other HTTP
 37% P2P
 17% newsgroups, streaming, gaming, VoIP
 In other words, mostly a waste of bits.

4. Internet…what's it good for?
 For years there has been a theory that
millions of monkeys typing at random on
millions of typewriters would reproduce the
entire works of Shakespeare…
The Internet has proven this theory to be
untrue. - Anonymous

5. Socket Programming
If a packet hits a pocket on a socket on a port,
and the bus is interrupted as a very last resort,
and the address of the memory makes your
floppy disk abort,
then the socket packet pocket has an error to
report!
from A Grandchild's Guide to Using Grandpa's
Computer by Gene Ziegler

6. Sockets programming
 a client exchanging data with a server
 An Internet socket is composed of the
following:
 Protocol (TCP, UDP, raw IP)
 Local IP address (your computer)
 Local port (your application)
 Remote IP address (another computer)
 Remote port (another application)

7. Server Sockets in Java
 package java.net
 ServerSocket server =
new ServerSocket(PORT);
// waits for network requests.
 Socket socket = server.accept();
// waits for a connection and returns a socket
 use java.io to exchange data
 InputStream from socket (client)
 OutputStream to socket (client)

8. Client Sockets in Java
 package java.net
 Socket socket = new Socket ( host, port);
// waits for a connection to host on a port and
returns a socket
 use java.io to exchange data
 InputStream from socket (server)
 OutputStream to socket (server)
 see PortScanner.java

9. URL and IP addresses
 URL class represents a
Uniform Resource Locator, a pointer to a
"resource" on the World Wide Web.
 see ReadURL.java
 InetAddress class represents an
Internet Protocol (IP) address.
 used to find out who the socket is talking to.
 ServerSocket or Socket can .getInetAddress();

10. Sockets Programming
see
 EchoServer.java & EchoClient.java
 simple two-way communication
 EchoServerThread.java & EchoClient.java
 multi-threaded server to handle many sets of
two-way communication