The Assignment $1$

You will write two programs, a server and a client. The server creates a socket in the Internet domain bound to port SERVER$\_$PORT $($a constant you should define in both programs, you may use last $4$ digits of your UM$-$ID$)$ last $4$ digits are $4652.$ The server receives requests through this socket, acts on those

requests, and returns the results to the requester. The client will also create a socket in the Internet domain, send requests to the SERVER$\_$PORT of a computer specified on the command$-$line, and receive responses through this socket from a server.

For this assignment, you just need to allow one active client connect to the server. In the next assignment, you should allow multiple clients connect the server at the same time.

Your client and server should operate as follows. Your server begins execution by opening a file that you have created and that contains the address book. Each record in the address book will have four fields, Record ID $(4$ digits$),$ First Name $($up to $8$ characters$),$ Last Name $($up to $8$ characters$),$ Phone Number $(12$ characters$).$ Your server should read these records into a server$-$internal data structure and keep track of the number of records. You may assume that you will

never have to store more than some fixed number, say $20,$ records. Once the server has initialized

its data structures, it should wait for the connection requests from the clients.

Your client operates by sending an ADD, DELETE, LIST, SHUDOWN, QUIT commands to the

server. You should create a client that is able to send any of the five commands above, and allows a user to specify which of the commands the client should send to the server.

The details of the protocol depend on the command the client sends to the server.

ADD

Add a name and number record to the address book. A client sends the ASCII string $$ADD$"$

followed by a space, followed by a First Name, followed by a space, followed by a Last Name,

followed by a space, followed by a Phone Number, and followed by the newline character $($i$.$e$.,\text{'}\backslash$

n$\text{'}).$

$1$

When the server receives an ADD command from a client, it will add a new record in the address

book and return the $200$ OK$$ message.

A client$-$server interaction with the ADD command thus looks like:

c: ADD Jinhua Guo $313-583-6439$

s: $200$ OK

The new Record ID is $1001$

DELETE

Delete a record from the address book. A client that sends the ASCII string "DELETE", followed

by a space, followed by a Record ID$,$ followed by the newline character $($i$.$e$.,\text{'}$

$\text{'}).$ The client

should then wait for the server to return a $"200$ OK$"$ message $($indicating that the record is

successfully deleted$),$ or a $"403$ The Record ID does not exist."

A client$-$server interaction with the DELETE command thus looks like:

c: DELETE $1001$

s: $200$ OK

LIST

List all records in the address book.

A client$-$server interaction with the LIST command looks like:

c: LIST

s: $200$ OK

The list of records in the book:

$1001$ Jinhua Guo $313-583-6439$

$1002$ John Smith $313-583-1234$

$1003$ Mary Miller $313-594-4567$

SHUTDOWN

The SHUTDOWN command, which is sent from the client to the server, is a single line message

that allows a user to shutdown the server. A user that wants to shutdown the server should send

the ASCII string "SHUTDOWN" followed by the newline character $($i$.$e$.,\text{'}\text{'}).$

Upon receiving the SHUTDOWN command, the server should return the string $"200$ OK$"$

$($terminated with a newline$),$ close all open sockets and files, and then terminate.

A client$-$server interaction with the SHUTDOWN command looks like:

c: SHUTDOWN

s: $200$ OK

$2$

QUIT

Terminate only the client. The client exits when it receives the confirmation message from the

server.

A client$-$server interaction with the QUIT command looks like:

c: QUIT

s: $200$ OK

Note, $300$ invalid command$$ or $301$ message format error$$ should be returned to the client, if a server receives an invalid command or the command in the wrong format. $*$

$*$ Server.java

$*/$

import java.io$.*$;

import java.net.$*$;

public class Server $\{$

public static final int SERVER$\_$PORT $=5432$;

public static void main$($String args$[])$

$\{$

ServerSocket myServerice $=$ null;

String line;

BufferedReader is;

PrintStream os;

Socket serviceSocket $=$ null;

$//$ Try to open a server socket

try $\{$

myServerice $=$ new ServerSocket$($SERVER$\_$PORT$)$;

$\}$

catch $($IOException e$)\{$

System.out.println$($e$)$;

$\}$

$//$ Create a socket object from the ServerSocket to listen and accept

connections.

$//$ Open input and output streams

while $($true$)$

$\{$

try

$\{$

serviceSocket $=$ myServerice.accept$()$;

is $=$ new BufferedReader $($new

InputStreamReader$($serviceSocket$.$getInputStream$()))$;

os $=$ new PrintStream$($serviceSocket$.$getOutputStream$())$;

$//$ As long as we receive data, echo that data back to the client.

while $(($line $=$ is$.$readLine$())!=$ null$)$

$\{$

System.out.println$($line$)$;

os$.$println$($line$)$;

$\}$

$//$close input and output stream and socket

is$.$close$()$;

os$.$close$()$;

serviceSocket.close$()$;

$\}$

catch $($IOException e$)$

$\{$

System.out.println$($e$)$;

$\}$

$\}$

$\}$

$\}$

make necessary changes in this code as per the conditions mentioned in the question.