The Assignment 2 Specification and Marking Criteria
Peer-to-Peer Content Distribution and Distributed Query
The application background
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), 7282. (available at http://zoo.cs.yale.edu/classes/cs426/2012/bib/rodrigues10peer-to-peer.pdf on 15th Jan 2020).
In this assignment, you are to develop a particular Peer-to-Peer (P2P) application – content distribution and distributed query. The application allows peers to form an overlay and share information on 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 (requester) queries a question, it multicasts a request including the question to the peer overlay. Any peers (repliers) that have an answer to the question will respond to the requester. 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. In addition to multithreading and UDP packets, IP multicast must be used to form the peer overlay. Thus, you will need to review 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) before starting this assignment. Client/server model is also used for this assignment as a peer is a client and a server at the same time.
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.
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 the 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 reply port for answers.
6. To simplify the problem, we assume that the answer to a query 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).
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: 188.8.131.52 and 8888 are the IP multicast address and port number that were used in this example. Other IP multicast addresses and port numbers can also be used for this assignment.
PPP1 joins (using port 7896 as the UDP reception port to receive answers)
In the above example, clicking the Set button will bring PPP1 into full function by joining the multicast group, initialising the service threads for querying questions and receiving answers and enabling the Query button.
PPP2 and PPP3 start and join the peer overlay in the same way as shown by the following screenshots.
2. The following screenshots show the single-answer examples:
PPP1 queries ‘What is cloud computing?’ 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 “What is peer-to-peer system?’ Only PPP3 has the answer and replies.
PPP3 queries “What is distributed system?’, Only PPP1 has the answer and replies.
3. The following screenshots show the multiple-answers examples. Note the multiple-answer function is required by this assignment.
PPP1 queries ‘What is 5G?’, PPP2 and PPP3 have answers and reply.
PPP2 queries ‘What is fault tolerance?’, PPP1 and PPP3 have answers and reply.
PPP3 queries ‘What is smartphone?’, PPP1 and PPP2 have answers and reply
The aforementioned examples have shown the equity between peers, that is, every peer is both a client and a server to share contents by distributed processing. Your implementation must satisfy all the aforementioned 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. Description of key potential problems with IP multicast.
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 IDE from Oracle.
• The compiled Java class files of the source code. These Java classes must be runnable on the standard JRE (Java Runtime Environment) from Oracle
Note: an easy way to provide the source code and executables is to submit them in a NetBeans project.
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 application is compilable and runnable 2
2. Whether the peer is able to take the role of both a client and a server 2
3. Whether the general structure of peer is sound 2
4. Whether the overlay is formed correctly by IP multicast 2
5. Whether 2 communication channels, one for multicast and the other for answer reception, is structured correctly for each peer 2
6. Whether a peer is able to multicast a query request by using a UDP datagram 2
7. Whether the query request encapsulates a peer’s ID and UDP reception port and a question 3
8. Whether the data structure of question bank of each peer is sound 3
9. Whether the query request from a peer itself is ignored 1
10. Whether single-answer and multiple-answer function are correctly implemented 3
11. Whether multithreading is used when concurrency exists 3
12. Whether the 3 test peers are provided 2
13. Whether the source code is readable and necessary inline comments are provided for the source code 2
Part 2: Documentation 6
1. Whether the user instruction covers compiling, installation and starting of the application 2
2. Whether the user instruction covers the tests of both the single-answer and multi-answer cases 2
3. Whether the key potential problems with IP multicast are addressed 2
Sub Total for Assignment 2 35
Late Penalty -1.75 (5% each calendar day, either full or part)
Plagiarism Related Penalty
Total for Assignment 2