Assignment Overview

The basic funcationlity you will implement is a client and server that communicate over the Internet. The server is essentially an echo server but with some additional functionality. Instead of simply echoing the string it receives, the server returns a string with all upper case letters replaced by lower case letters and every space changed to a `.'. See below for an example.

The server will receive a text string of up to 80 characters length. The server is expected to run on one machine and wait for requests. Your client code will contact the server using its host address (IP host or address and port number) and pass it a string. The server will then change this string and send it back to the client. The client will display the received string and exit.

Example

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dagwood> server 32000 <enter>
[Eventually, after the server responds, it should just exit]
dagwood>

Then you ran a client on a machine (blondie in the example) using the following arguments:

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blondie> client dagwood.cs.ucsb.edu 32000 <enter>
Enter text: This is my text to be changed by the SERVER. <enter>
this.is.my.text.to.be.changed.by.the.server.
blondie>

• The client should send the string, wait for a response, print the response and then exit.

• After sending the modified text string, the server should exit.

• The client should accept as input either a host name or an IP address and then the port number.

• The client does not need to do any error checking, e.g. check to see if the host name or IP address is valid, check to make sure the string is less than 80 characters, etc.

• If there are no upper case letters and no spaces, the server will return the exact same string that is sent.

Your task is to write client and server programs in C {\it and} in Java using UDP {\it and} TCP. You will end up writing (and turning in) 8 different programs:

1- Server in C using UDP     (file name to turn in : server-c-udp.c)
2- Client in C using UDP        ( file name to turn in : client-c-udp.c)
3- Server in C using TCP        ( file name to turn in : server-c-tcp.c)
4- Client in C using TCP        (file name to turn in : client-c-tcp.c)

5- Server in Java using UDP     (file name to turn in : server_java_udp.java)
6- Client in Java using UDP        (file name to turn in : client_java_udp.java)
7- Server in Java using TCP        (file name to  turn in : server_java_tcp.java)
8- Client in Java using TCP        (file name to turn in : client_java_tcp.java)

You will be turning in 8 (and only 8--no header files... NOTHING else) files as named above. Your server should not output anything (status, debugging messages, etc.) and your client should have the exact same interface as given in the above example. (Code will be run against an automated checker... any deviation (e.g. printing additional messages, etc.) will be counted as incorrect.

In order to compile your C code, use the following commands as a guide:

gcc -g -o client client.c -lsocket -lnsl
gcc -g -o server server.c -lsocket

To compile your Java code, use the following commands as a guide:

javac server_java_udp/tcp.java
javac client_java_udp/tcp.java

Assignment Turnin

csil-machine> turnin hw1@cs176b hw1

ANOTHER NOTE: It is highly recommended that you use the CSIL machines to do this assignment. All of the tools you will need are available there; it significantly improves our ability to help you if you have problems; and it ensures that if your programs work there, they will work when we grade them.

Assignment Grading

• 35 pts: UDP client & server in the first language
• 35 pts: TCP client & server in the first language
• 15 pts: UDP client/server in the second language
• 15 pts: TCP client/server in the second language

In addition to correctness, part of your grade will depend on how well your code is written and documented. NOTE: good code/documentation does not imply that more is better. The goal is to be efficient, elegant and succinct!