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The Assignment 2 Specification and Marking Criteria
Peer-to-Peer Content Distribution and Distributed Query
In distributed computing, a peer is both a client and a server at the same time, being able to request
services from other peers or providing services to other peers. For the general knowledge about
peer, you can read the following academic article.
Rodrigues, R., Druschel, P., 2010. Peer-to-Peer Systems, Communications of the ACM. 53(10), 72-
82. (available at http://zoo.cs.yale.edu/classes/cs426/2012/bib/rodrigues10peer-to-peer.pdf on
23rd Dec 2017).
In this assignment, you are to develop programming skills of peer via a particular Peer-to-Peer (P2P)
application – content distribution and distributed query. The application allows peers to form an
overlay and share information from the entire peer overlay. In this assignment, you will need to
upgrade a client and a server into a peer. The peers are to form an overlay by IP multicast and the
information stored in a peer can be shared by any other peers. When a peer queries a question, it
will multicast a request including the question to the peer overlay and the peer that has the answer
to the question to respond to the requester peer. To query a question, a UDP datagram via IP
multicast is used. Once the answer is found, replying the answer is to use another separate UDP
communication between the requester and the replier. To complete this assignment, you need to
complete the following 2 parts.
Part 1: Peer overlay design and implementation
In this part, you are to develop the simplified system of content distribution and distributed query.
The assumptions on the system are specified as follows.
1. Each peer has a unique ID.
2. Peers form a networking overlay by IP multicast (reference to Chapter 4.4 of the textbook,
Week 5 lecture slides, Week 6 lab projects, and search for other academic articles about IP
multicast if necessary).
3. Each peer has a number of answers to some questions that can be shared by other peers.
4. Once a peer has a question, it needs to compose a request, including the question and
communication information such as reply IP address and port number.
5. Each peer can multicast a query request to all other peers in the overlay. After that, the peer
is waiting on the port for answers.
6. To simplify the problem, we assume that the answer to a queried question can always be
found from at least one peer.
7. Once the answer to the question is found, the replier peer (the one who has the answer) will
use a UDP datagram to send the answer to the requester peer (the one who asks the
question).
http://zoo.cs.yale.edu/classes/cs426/2012/bib/rodrigues10peer-to-peer.pdf
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8. A peer needs to ignore the requests from itself because by default IP multicast sends a
message to every peer on the overlay.
The following screenshots show an implementation of the system of content distribution and
distributed query.
1. The 3 peers (with ID of PPP1, PPP2 and PPP3) join the same IP multicast group. Note:
228.5.6.7 and 8888 are the IP multicast address and port number that were used in this
example.
PPP1 joins (using port 7896 as the UDP port to receive answers)
In the above example, clicking the Set button will bring PPP1 into full function by joining the
multicast group and initialising the service threads for querying questions and receiving
answers.
PPP2 and PPP3 start and join the peer overlay in the same way as shown by the following
screenshots.
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2. The following screenshots show the single-answer examples:
PPP1 queries Question 2, only PPP2 has the answer and replies. Note: entering a question on
PPP1’s Question text field and clicking the Query button will multicast the question to the
peer overlay and query to all the peers.
PPP2 queries Question 3, only PPP3 has the answer and replies.
PPP3 queries Question 1, only PPP1 has the answer and replies.
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3. The following screenshots show the multiple-answer examples. Note the multiple-answer
function is required by this assignment.
PPP1 queries Question 5, PPP2 and PPP3 have answers and reply.
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PPP2 queries Question 6, PPP1 and PPP3 have answers and reply.
PPP3 queries Question 4, PPP1 and PPP2 have answers and reply
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The above example shows the equity between peers, that is, every peer is both a client and a server
to share contents and distributed processing. Your implementation must satisfy all the above
requirements in order to get the full mark.
Part 2: Documentation
On completion of the implementation of the framework, prepare a document to include:
1. An end user’ instruction about how to compile, run and test your system.
2. The key issues about upgrading a client and a server to a peer and overlay forming.
Submission
You need to provide the following files in your submission.
1. At least 3 peers in 3 individual folders, of which each folder contains:
• Files of Java source code of the implementation. The in-line comments on the data structure
and program structure in the programs are required. These source code files must be able to
be compiled by the standard JDK (Java Development Kit) or NetBeans from Oracle
(http://www.oracle.com/technetwork/java/index.html).
• The compiled Java class files of the source code. These Java classes must be runnable on the
standard JRE (Java Runtime Environment) or NetBeans from Oracle
(http://www.oracle.com/technetwork/java/index.html).
2. A Microsoft Word document to address the issues as specified in Part 2 above.
All the required files must be compressed into a zip file for submission. You must submit your
assignment via the online submission system from the unit web site. Any hardcopy or email
submission will not be accepted. After the marked assignments are returned, any late submissions
will not be accepted.
The Marking Criteria
Marking Criteria Available Marks
Part 1: Peer overlay design and implementation 29
1. Whether the peer is able to take the role of being both a
client and a server
2
2. Whether the general structure of peer is sound 2
3. Whether the overlay in terms of 2 communication
channels, one for multicast and the other for answer
reception, is structured correctly
2
http://www.oracle.com/technetwork/java/index.html
http://www.oracle.com/technetwork/java/index.html
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4. Whether a peer is able to create and join the IP multicast
group
2
5. Whether a peer is able to multicast a query request by
using a UDP datagram
2
6. Whether the request encapsulates a peer’s ID and UDP
reception port and a question
3
7. Whether the request from a peer itself is ignored 2
8. Whether multiple-answer function is correctly
implemented
3
9. Whether a service thread is used when necessary 2
10. Whether the application is compilable and runnable 2
11. Whether the 3 test peers are provided 3
12. Whether the source code is readable 2
13. Whether necessary in-line comments are provided 2
Part 2: Documentation 6
1. Whether the instruction covers compiling and starting of
the application
2
2. Whether the instruction covers the tests of both the
single-answer and multi-answer cases
2
3. Whether the key issues about upgrading a client and a
server to a peer and overlay forming are addressed
2
Sub Total for Assignment 2 35
Late Penalty -1.75 (5% each calendar
day, either full or partial)
Plagiarism Related Penalty
Total for Assignment 2