CS1004 Information Systems & Organisations

Requirement

something a system must do/ a quality a system must have

Functional vs Non-Functional Requirements

functional is WHAT a system must do

non-functional is HOW the system must perform it

Feasibility study considers:

is it needed, can it be done, within budget, resources and time?

Statement of scope

A short concise statement of the primary purpose of the primary purpose/ function/ role of the system being developed. It states what will be in the system and what won't.

What does a use case do?

A use case is used within the requirement analysis and describes how a primary actor interacts with the system to achieve a goal. It also describes the system's behaviour as it responds to a request from an actor.

'Who' does 'What' with the system to achieve 'Which goal'.

Primary actor

Primary actors are people, or at times even other systems, that initiate an interaction with the system.

Actor

A stakeholder who interacts with the system during the use case (doesn't start it off- that's primary actor).

Stakeholder

Someone with a vested interest in the behaviour/ outcome of the use case.

Goal

What the actor in a use case wants to achieve through interacting with the system.

Scope

The scope defines the boundaries of the system in terms of its requirements (what it must do) and what explicitly isn't required.

Main Sequence

The sequence of steps/ events that occur in a case where nothing goes wrong. The ideal set of events that take place in a successful outcome of achieving a goal.

What do use cases capture?

The functional requirements/ intended behaviour of a system.

What are the two levels of detail when it comes to use cases?

Casual: contains Primary actor, Goal, Scope, Main success sequence.

Fully-dressed: contains Supporting actors, Stakeholders, Trigger, Precondition, Guarantees.

Trigger

The event that initiates the use case. What causes the actor to start it.

Pre-conditions

What must be true before the use case can take place.

Guarantees

The outcome that must be true after the use case has occurred.

Difference between Success Guarantee and Minimum Guarantee?

Success Guarantee: the outcome after a successfully run-through use case.

Minimum Guarantee: however the use case must end if not as the main sequence.

The sequence for use case with extensions

Primary Actor

Goal

Scope

Stakeholders

Supporting actors

Trigger

Precondition

Main sequence

Extensions

Success Guarantees

Minimum Guarantees

Entity

Something which an organisation may wish to hold data such as 'Student', 'Module'...

Attribute

The data we need to know/ collect about each entity such as 'name', 'studentID', 'DOB'...

What are the 5 types of attributes?

Simple (atomic): e.g. item_number

Composite: e.g. name = title + initial + surname

Single-valued: e.g. quantity

Multi-valued: e.g. hobbies

Derived: e.g. wage FROM hours_worked * hourly_rate

Attribute domain

A set of all possible values for an attribute. Such as the domain for 'months' could be Jan, Feb, March...

Relationship

How two or more entities are linked to one another.

Cardinality

How many instances of an entity relate to each instance of another entity.

Primary Key

An attribute that uniquely identifies an entity.

Events cause entities to...

Change state

Event

Something that happens in the environment.

State

A recognisable period in life of an object.

What is the 8 step process of Information Systems Development?

1. Project Initiation

2. Feasibility study

3. System analysis

4. System design

5. Implementation

6. Validation

7. Deployment

8. Maintenance

What are the 3 constraints of information systems development?

1. Scope

2. Time

3. Cost/ resources

Methodology

A set of procedures, techniques, tools, notations and documentation that helps a team to plan, manage, control and evaluate Information Systems Projects.

Advantages of waterfall methodology

- Practical and easy to use

- Simple structured approach (even novices can follow)

- Emphasis on documentation which makes it clear what phase the team is on

- Traceability and management facilitated

- With detailed documentation a new team can pick up where it was left off.

Disadvantages of waterfall methodology

- Requirements are always subject to change, waterfall is not as flexible to take on these changes.

- Slow and rework may take a while

- Low Flexibility, flows in one direction, very difficult to go back to change something

- Distance from users, only communication at the start and end of the process

- Errors may only be identified at the very end when testing is done

-Detailed documentation takes a lot of time and resources which aren't useful for small projects

- More prone to delays

Agile concepts

- minimal documentation as focused on providing software fast

- focuses on customer collaboration

- flexible to change

- extensive use of tools to speed up development ( code generator, automated tests)

- fixed resources (and therefore fixed budgets)

- accepts uncertainty as software is being released through iterative development

- better for small/ medium software

- no power hierarchy

- experienced developers

Product Backlog

A prioritized list of user stories, showing both short- and long-term goals of a software development. Normally the initial backlog contains just enough to get the development team started. More user stories/ use cases added throughout the process.

User stories

Describes features from the POV of the user which highlight a piece of functionality of the software. The template they follows is "As a... I want... So that...".

In terms of Feature prioritising, what does MoSCoW stand for?

M- must have

S- Should have

C- Could have

W- Won't have

What are the 3 key roles in Scrum development?

Product Owner: Represents the client, develops product backlog.

Scrum Master: Team and process facilitator.

Development team: team of 5-9 people responsible for creation of software.

Sprint

A full development cycle (design, implementation, testing) focusing on a user story/stories with a fixed length in advance ~4 weeks.

At the end of each Sprint, we have a working software, referred to as a potentially shippable product.

Corporate stakeholders

Person/ group/ organisation/ system who affects or can be affected by an organisation's action. e.g. employees, suppliers, customers...

The stakeholder theory classifies stakeholders by 3 characteristics, which are?

Power: the extent stakeholders can impose their will onto the project.

Legitimacy: The extent to which their involvement is appropriate.

Urgency: The extent to which the stakeholder believes it is critical to act now on their claims.

What does the stakeholder theory help with?

Helps identify what stakeholders should be consulted or 'managed'.

Soft Systems methodology

Focuses on better understanding the business and attempts to find a solution to the 'problem' without a information system development.

Rich Pictures

A cartoon visualisation of a situation based on field research, interviews...

They depict stakeholders, relationships, processes and view points.

These are used to help detangle complex situations.

Root definition

A description of what the system does, how, and why using CATWOE.

What does CATWOE stand for?

Customers: who the system serves.

Actors: who carry out the activities.

Transformation Process: what the system does what inputs get converted to outputs.

World View: the 'bigger picture', what matters in the world.

Owner: who has the power to change/ create the system.

Environment: relevant environment factors.

Conceptual model

The network of processes/ activities that must be done to satisfy the root definition. Compare with current state to plan what needs to change to go from current state to the next.

Business Strategy

The plan/ direction of an organisation for long-term plans.

SWOT analysis

Used to assess and understand a strategy, project, investment, or business decision in terms of internal factors- Strengths and Weaknesses, and external factors- Opportunities and Threats.

PESTLE analysis

An analysis tool focusing on the eternal business environment of the company. Tracks external factors that can affect activities & position of the company. This analysis can be especially good for a business considering a new product.

What does PESTLE stand for?

Political, Economic, Social, Technological, Legal, Environmental

Business model

A plan that details how a company creates, delivers, and generates revenues. A business model may also attract investors.

List the types of business models

Franchise, Subscription, Freemium, Advertisement, Retailer, Manufacturer, Distributor, Leasing, Razor Blades, Crowdsourcing, Peer-to-peer/platform.

Value Proposition

What the product/ service offers to the customers.

What are the 2 components of Revenue Model?

The cost structure: All expenses the business uses to deliver value to customers.

The revenue streams: All revenue streams the business utilises.