Sockets - the deep end of networking

You have already been doing networking!

• Embedding your Java applets in web pages
• Downloading images and sounds in your applets
• Connecting to a URL and reading from it - your database program
  • Uniform Resource Locator
  • the URL class

What is under all this?

• Important words

• TCP/IP Tutorial
• TCP/IP again
• Everything you wanted to know but were afraid to ask
• List of well known ports

How do you do it in Java?

• Sun's tutorial
• Java Socket Tutorial
• Socket Programming chapter from Java Unleashed
• More on Java Sockets

• Sample code
  • EchoClient from the tutorial
  • HttpClient
  • Socket Server and Client

  • Sockets in an applet

  • A Java chat program 42,466 bytes compressed :)
  • Java Chat Project, with source code

• Some "magic words" that ftp understands

  ABOR

  abort command

  LIST

  lists the specified files or directories

  PASS

  submits the specified password

  QUIT

  ends session

  RETR

  gets the specified file

  STOR

  puts the specified file

  SYST

  server returns the system type

  TYPE

  specify type - A for ascii, I for binary (image)

  USER

  submits the specified user name

Assignments

• For Friday Nov. 13 (!!!) be prepared to write a server that listens at a port and a client that can "talk" to ports that other students write.
  
• For Tuesday Nov. 17, find out how to "talk" to one of the well known ports not covered in class. Write a Java application that demonstrates at least minimal use of the port.

• Extra Credit (20) - modify your database program so it reads from a socket that you set up instead of from the URL.