Programming Assignment 1

Objective of this assignment:

.     Develop and implement a simple application using UDP sockets. The client must be implemented in Java. The server can be implemented in Java or in your preferred 1 language (different from Java) for a 5 points bonus. Insure that your preferred language is already installed and available on Tux machines. It is your responsibility to check ahead: do not check/test at the last minute.

What you need to do:

1.   Implement a simple UDP Client-Server application

Objective:

The objective is to implement a simple client-server application using a safe method: start from working code for the client and the server. You must slowly and carefully bend (modify) little by little the client and server alternatively until you achieve your ultimate goal: meeting all requirements for this assignment. You must bend and expand each piece alternatively the way a black-smith forges iron. From time to time save your working client and server such that you can roll-back to the latest working code in case of bugs. Not using this "baby steps" strategy may leave you with a ball of wax hard to debug.

For this programming assignment, you are advised (optional, not mandatory) to start from the Friend client and server code (see lecture and resources) to implement this simple application. The Friend app was presented during the lectures. Consider using Wireshark to check whether the protocols you implement meet this assignment requirements. If using a language other than Java for the server, you are on your own. Ensure that your preferred language is already available on Tux machines. It is your responsibility to timely check. Start ahead. Do not wait until the last minute.

Hint: look at how to “ How to get started?” below

Part A: Datagram socket programming

The objective is to design a Calculating Server (CS). This calculating server performs bitwise  Boolean and arithmetic computations requested by a client on signed integers. Your server must offer the following operations:  1) addition (+), subtraction (-), 3) bitwise OR (|), 4) bitwise AND (&), 5) division (/), and 6) multiplication (*).

A client will form a request  following  this protocol (byte per byte):



TML

Op Code

Operand 1

Operand 2

Request ID

Op Name Length

Op Name

Size (bytes)

1

1

4

4

2

1

Variable

Where

1) TML is the Total Message Length (in bytes) including TML. It is an integer representing the total number of bytes in the request.

2) Op Code is a number specifying the desired operation following this table

Operation

*

/

|

&

-

+

OpCode

0

1

2

3

4

5

3) Operand  1 is a signed number making the first operand

4) Operand 2 is a signed number making the second operand

5) Request ID is the request ID. This number is generated by the client to differentiate requests. You may use a variable randomly initialized and incremented each time a request is generated.

6) Op  Name Length is the length in bytes of the operation name (see below what the Operation Name is).  Pay attention: the length is the number of bytes used to encode the string. Recall that some encoding schemes use two bytes per character.

7) Op   Name is   name   of   the   requested  operation:   "addition",   "subtraction",  "or",  "and",  "division",  and "multiplication". The Op Name string must be encoded using "UTF- 16BE".

Operands are sent in the network byte order (i.e., big endian).

Hint: create a class object Request like "Friend", but with the fields needed for a request ...

Below are two examples of requests. Bytes in the array are hexadecimal numbers.

Request 1: suppose the Client requests to perform the OR operation 240 | 4: (This is the 5th request) (240) 10  = 0xF0 and (4) 10  = 0x04. We omit the “0x” prefix for each byte expressed in hexadecimal.

11 02 00 00 00 F0 00 00 00 04 00 05 04 0**F 00 72

Request 2: suppose the Client requests to perform the operation 227 &  183  (if this is the  12th  request):

13 03 00 00 00 E3 00 00 00 B7 00 0C 06 0**1 0**E 0**4

The Server will respond with a message with this format:

Total Message Length (TML)

Result

Error Code

Request ID

one byte

4 byte

1 byte

2 byte

Where

1) TML is the Total  Message Length (in bytes) including TML. It is an integer representing the total numbers of bytes in the message.

2) Result is the result of the requested operation

3) Error Code is 0 if the request was valid, and 127 if the request was invalid (Message length not matching TML)  4) Request ID is the request ID. This number is the number that was sent as Request ID in the request sent by the

client. This will allow the client to match the results to the appropriate request.

In response to Request 1 (240 | 4) below

11 02 00 00 00 F0 00 00 00 04 00 05 04 0**F 00 72

the server will send back: (. We omit the “0x” prefix for each byte expressed in hexadecimal. )

08 00 00 00 F4 00 00 05

In response to Request 2 (227 &  183 ),

13 03 00 00 00 E3 00 00 00 B7 00 0C 06 0**1 0**E 0**4

the server would send back:

08 00 00 00 A3 00 00 0C

a) Repetitive Server: Write a datagram Calculating Server (ServerUDP.xxx). This server must respond to requests as described above. The server must bind to port (10010+TID) and could run on any  machine  accessible  on the  Internet. TID is  your  Canvas  team  #. The  server  must  accept  a command line of the form: prog ServerUDP portnumber where prog is the executable, portnumber is the port the server binds to. For example, if your Team ID (GID) is Team  13 then your server must bind to Port #  10023.

Whenever a server gets a request, it must:

i.   display the request one byte at a time in hexadecimal (for debugging and grading purpose)

ii.   display the request in a manner convenient for a typical Internet user: the request ID and the request (operands and required operation)

b)   Inplement a datagram client (ClientUDP.xxx)

i.   Accepts a command line of the form: prog ClientUDP servername PortNumber where prog is the executable, servername is the servername, and PortNumber is the port number of the server. Your program must prompt the user to ask for an Opcode, Operand1 and Operand2 where OpCode is the opcode of the requested operation (See the opcode table). Operand1 and Operand2 are the operands. For each entry from the user, your program must perform the following operations:

ii.   form a request as described above

iii.   display byte per byte in hexadecimal the request that will be sent

iv.   send the request to the server and wait for a response

v.   display the server’s response byte per byte in hexadecimal (for debugging and grading purpose)

vi.   display the  response of the server  in a manner convenient for a typical Internet user: the request ID, the response and the error code (display Ok when error code is 0)

vii.   display the roundtrip time (time between the transmission of the request and the reception of the response)

viii.   prompt the user for a new request. (Use some way to allow a client to quit. Just be explicit about how to quit)

To implement the server, you should consider (optional) starting with the Friend code. If you implement a successful server in a language different from Java, you will get 5 points Bonus points. For the language other than Java, the only constraint is that it must already be installed on Tux machines. Check the Tux machines for your chosen language before you start implementing.

Your code must be neat and pleasant to read. Comment the code appropriately. If starting from some  other  code, delete all   unnecessary   instructions (do not  just comment  out the   unnecessary instructions). A code not neat or pleasant will be penalized up to -30 points.

Data collection and analysis

For the client, report separately the min, average, and max round trip time. Include screenshots of your client and server executing on the Tux machines. Screenshots on machines other than the Tux machines will not receive any credit. To receive any credit, the screenshots must clearly show the Tux machine name, the username of one of the classmates, and the date. In other words, if any information (username, date, or tux machine name) is missing, the assigned credit for the assignment will be 0. You must have two screenshots: one for the server and one for the client. Here is a screenshot containing the Tux machine, a username, and a date. Avoid screenshots too small. If screenshots are not easily and conveniently readable, they will be considered missing. Screenshots must be easily and conveniently readable.



How to get started?

1) Download all files (UDP sockets) to run the "Friend" application used in Module 2 to illustrate how any class object can be exchanged: Friend.java, FriendBinConst.java, FriendEncoder.java, FriendEncoderBin.java, FriendDecoder.java, FriendDecoderBin.java, SendUDP.java, and RecvUDP.java.

2) Compile these files and execute the UDP server and client. Ensure they work.

3) Create a new folder called Request and duplicate inside it ALL files related to the Friend class object     4) Inside the Folder Request, change ALL occurrences of "Friend" with "Request" including the file names. 3) Adapt each file to your application. Replace the fields used by Friend with the fields used by a request.

4) Aim to have the client send one request and have the server understand it (just like what we did with a friend object).

5) When your server will receive and print out correctly a request, then you need to send back a response... 6) Create a class object Response....

Report (a missing report incurs a 30 points penalty)

.     Write a report that will report your results..

.     Your report must contain the following information:

o  whether the programs work or not (this must be just ONE sentence)

o  the directions to compile and execute your programs

o  the information this assignment asks you to report (minimum, average, and maximum round trip times) and the

required screenshots of the execution of the client and server. To receive any credit, the screenshots must clearly show the Tux machine, the username of one of the classmates, and the date. To get the date, just run the command date before executing your programs. Each missing or incomplete screenshot will result in a 50 points penalty.

What you need to turn in:

.      Electronic copy of your source programs (standalone, i.e. NOT in a zipped folder)

.      Electronic copy of the report (including your answers) (standalone, i.e. NOT in a zipped folder). Submit the file as a Microsoft Word or PDF file.

. In addition, put all files in a zipped folder and submit the zipped folder.

Grading

1) Client is worth 40% if it works well:

a) meets the protocol specifications (20%) and the user interface ( 10%)

b) communicates correctly with YOUR server (10%). Furthermore, screenshots of your client and server running on Tux machines must be provided. The absence of screenshots or Screenshots on machines other than the Tux machines will incur 50 points penalty per missing screenshot

2) UDP client is worth  10% if it works well with a working server from any of your classmates.

The server is graded the same as the client (30% +  10% +  10%).
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