代写 Computer Networks and Distributed Systems

100%原创包过,高质量代写&免费提供Turnitin报告--24小时客服QQ&微信：273427

527 — Computer Networks and Distributed Systems —

Assessed Coursework: RMI and UDP

E.C. Lupu and D. Sgandurra

Due Date: Wednesday 16 March 2016

The purpose of the exercise is to gain experience of coding RMI and UDP as well as to compare them

for relative reliability and ease of use.

For each case you will have to write a simple client that passes a specified number of messages to a

server. Each message should contain a message sequence number and the total number of messages to

be sent. The server keeps track of the messages received and, when there are no more messages, outputs

a summary of the number of messages received and also which ones were lost.

When the clients and servers for each communication mechanism are working, run some experiments

on 2 computers in different parts of the lab (i.e., not physically near each other), sending increasing

numbers of messages (e.g., from 20-100 with increments of 20, then, 200, 300 and 400) and identify the

situations in which messages are lost.

Do not send more than about 2000 messages as otherwise you will overload the lab network.

You should hand in the following as hardcopy:

1. A short summary (no more than 1 page) describing your findings from running the programs. You

should address the following points:

(a) For each mechanism, what are possible causes, if any, of messages being lost?

(b) Are there any patterns in the way messages are lost?

(d) Which was easier to program and why?

2. Proof that the both RMI and UDP programs actually ran, e.g. console logs or screen dump plus an

indication of which message numbers, if any, were lost.

3. A well formatted listing of the completed code for the 4 classes (2 client server pairs) which is easy

to read. Start each of the 4 classes on a new page and avoid very long lines (i.e. <70 characters).

Your solutions should deal with exceptions appropriately.

Please provide program listings in the following order:

1. RMI Client

2. RMI Server

3. UDP Client

4. UDP Server

Notes:

Download outline source code and scripts from CATE. You are not obliged to use these; how-

ever, they should simplify the process of achieving working solutions. A few notes on the layout

and support files follow:

After extracting the files from the archive provided, you should run install.sh (or install.bat on

Windows) to obtain the appropriate build and execution scripts which are described below.

The class MessageInfo (in the common folder) provides a container for the data to be sent and

also has a constructor that extracts the data from a string representation. Outline code for each

of the client/server pairs can be found in the rmi and udp folders.

The file policy is a simple configuration file required for the RMI code. More constrained

policies are possible, but this should provide the lowest barrier to testing.

The Makefile allows Linux users to use make to compile the various parts of the exercise. It

can also be used to help configure your preferred development environment with the correct

commands, flags and parameters. Windows users can use the build.bat script to compile the

exercise in the same way. The other shell scripts (rmiclient (.bat or .sh) etc.) allow users to

execute the various parts of the exercise.

Tutorials

Sockets: http://docs.oracle.com/javase/tutorial/networking/sockets/

Datagrams: http://docs.oracle.com/javase/tutorial/networking/datagrams/

RMI: http://docs.oracle.com/javase/tutorial/rmi/