Exercises

1. Compile and run the JabberServer and JabberClient programs in this chapter. Now edit the files to remove all of the buffering for the input and output, then compile and run them again to observe the results.
2. Create a server that asks for a password, then opens a file and sends the file over the network connection. Create a client that connects to this server, gives the appropriate password, then captures and saves the file. Test the pair of programs on your machine using the localhost (the local loopback IP address 127.0.0.1 produced by calling InetAddress.getByName(null)).
3. Modify the server in Exercise 2 so that it uses multithreading to handle multiple clients.
4. Modify JabberClient so that output flushing doesn’t occur and observe the effect.
5. Build on ShowHTML.java to produce an applet that is a password-protected gateway to a particular portion of your Web site.
6. (More challenging) Create a client/server pair of programs that use datagrams to transmit a file from one machine to the other. (See the description at the end of the datagram section of this chapter.)
7. (More challenging) Take the VLookup.java program and modify it so that when you click on the resulting name it automatically takes that name and copies it to the clipboard (so you can simply paste it into your email). You’ll need to look back at the IO stream chapter to remember how to use the Java 1.1 clipboard.

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