Module Code and Title: CO3219/CO4219/CO7219 Internet and Cloud Computing
Assignment Title: Cloud based Collaborative Whiteboard
Assessment Tutor: Ashiq Anjum Weighting Towards Module Grade: 30%
Date Set: 29/10/2020 Hand-In Deadline Date: 26/11/2020

Level of Collaboration: Individual Assignment

Internet and Cloud Computing
Assignment 2: Cloud based Collaborative Whiteboard (30
% marks)

Deadline: November 26, 2020

Cloud based Collaborative Whiteboard
There are over 250 members in a class. You need to design and develop a Cloud based Collaborative
Whiteboard that can be shared between multiple users of this class over the network. You need to
run this whiteboard in a distributed environment where people can join in either from their own
machines or from distributed class rooms. Your whiteboard should support for basic drawing features
such as line, circle, and rectangle as well as text anywhere in the whiteboard.

The Cloud based Collaborative Whiteboard should have the following features:
1. Distributed System Design (6 Marks)
You should propose a suitable architecture for your distributed whiteboard and then propose an
implementation plan to build the proposed system architecture.
You should consider mechanisms to achieve consistency, scalability, fault tolerance, concurrency and
performance in your architecture. You should also propose a suitable network model to manage traffic
and provide fault tolerance.
You should produce (and draw) an architecture of your distributed whiteboard system so that it can
be deployed in a cloud environment at later stages.

You should evaluate available cloud and distributed server architectures before you design and
implement your own distributed whiteboard system. You should have convincing reasons to justify
the technology choices that you have made for your architecture.
In this task you should have a clear understanding and justification of the tools and technologies that
you will use to implement your Cloud based Collaborative whiteboard.

2. Distributed State Management (6 Marks)
The Cloud based Collaborative Whiteboard should allow multiple users to draw simultaneously on a
shared interactive canvas.
When a new person joins the system the user should obtain the current state of the whiteboard so
that the same objects are always displayed to every active user.
The system should support a single whiteboard that is shared between all of the clients.
All the users should see the same image of the whiteboard and should have the privilege of doing all
the drawing operations.
When displaying the whiteboard, the user interface should show the usernames of other users who
are currently editing the same whiteboard. Users must provide a username when joining the
whiteboard.
3. Consensus and Leadership (4 Marks)
Users should vote to elect a leader who then has the admin rights. A new leader should be elected
using a consensus protocols (Paxos, Raft etc). This node/user essentially takes charge of the system,
we call this node the “leader”. When this node fails, then the system detects this and users should
elect another node to take the leadership role.
The leader should allow only a selected group of users/peers to write/draw on the whiteboard at the
same time. Other users who want to participate should wait in a queue to be given permission.
All the peers will see the identical image of the whiteboard, as well as have the privilege of doing all
the operations.
Only the leader of the whiteboard should be allowed to create a new whiteboard, open a previously
saved one and close the application.
4. Replication (4 Marks)
The copy of the whiteboard should be saved when all users have agreed to the whiteboard state that
meets their requirements. This should be achieved through implementing a consensus protocol.
The users/nodes/servers should respond with a “yes” or “no” vote regarding the transaction. If more
than 50 percent servers respond with a “yes” vote, the leader issues a commit operation to the servers
to make the transaction durable; i.e., the whiteboard state has been committed to all participating
servers (strongly consistent vs loosely consistent).
5. Performance and concurrency (4 Marks)
Users should be able to work on a drawing together in real time, without appreciable delays between
making and observing edits.
You can have multiple servers that communicate with each other or a single central one that manages
all the system state.
You have to consider when/what messages are sent across the network because sending/receiving
too many messages across users will have performance implications. This will require designing an
exchange protocol that establishes which messages are sent in which situation and the replies that
they should generate.
6. Docker Service (6 Marks)
You should create a Docker container for your cloud based whiteboard system and deploy it in the
Docker registry or anther registry of your choice. You should share the client details on how to access
your Docker container for the system so that we can test your implementation. All details accessing
and running your service should be written in step by step so that it only takes two minutes (max) to
test the complete functionality.
Submitting your Assignment
Please submit description of your architecture, salient features of your design, technology choices
made, service implementation details, screen shots of your implementation/execution and code as a
single pdf document. This document should also contain URLs as well as other details in accessing and
running your service. You should also provide a login and password for accessing the system.
The submission point for submitting the document has been setup in learning material “Assignment
2: Cloud based Collaborative Whiteboard”.
WARNING

Please do not use the code from publicly available sources. You may get a zero mark if it
is found that you have copied code from other colleagues or from publicly available
sources. The same applies to the documentation and design. This should be your own
work and you should not share it with anyone else.

Ashiq Anjum
29/102020


欢迎咨询51作业君