Stakeholders

Any person or organisation who is affected by the system in some way and so who has a legitimate interest. Any one who is affected by the system or who has influence on system development or use the system is a stakeholder.

For example:

Customers (e.g. End users and system owner(s), system managers)

Developers (requirement/system analyst, 3D designers, programmers, project manager etc.)

External stakeholders

What are the main factors which cause software failure?

Customer as stakeholder:

Didn’t meet the customer’s needs or misunderstood/ not fully captured their requirements.

Change requirements too often

Customers are lack of commitment to the project

Customers don’t understand the terminology,

Lack of communication with developers

Customers have unrealistic/high expectation to the project.

The system is no longer benefit to the business or customers.

Scenario: Online Furniture Purchase

The following scenario will be used to discuss the Use Case Modelling Approach to Requirements Capture.

Requirements:

1. Mr John Smith would like to purchase 3-seater sofas over Internet using the manufacturer’s web site which is called furniture4u.co.uk. This is family run business and provide great costumer services.

2. Computers classified into servers, desktops and portables e.g. tablet and mobile phone device.

3. Customer can select colour, fibre and style and delivery date, the system will able to the calculate total price.

4. To place order, the customer must join the membership and fill out the personal information, shipment and payment information.

5. New member will be given his/her user name and password

6. The system sends a confirmation e-mail message to the customer with details of the order.

7. Customer can check the order status, online and shipping details at any time when they login the system. The system should also allow the customer to cancel order or amend order. The system should able to process refund.

8. Additionally, the system should able to

verify the customer’s credentials and provide payment methods such as paypal, credit card or debit card payments.

request the ordered from the factory,

print an invoice and also send an invoice by email, to the customer, and

request the factory to ship the sofas to the customer.

9. This company uses shipping.com to shipping their furniture to their company. (Outsourcing)

How to identify actors?

Actor represents a role that interacts with the system. Such as human e.g. end users, system managers; time e.g. can trigger event: automatic send an ordering confirmation email to customer. ;hardware device e.g. printer, data projector etc.

Tip:

1. look all the nouns in your scenario e.g. customer, salesman etc.

2. Actor names should clearly indicate the actor’s job role. E.g. if John is a student as a actor. You should use student as your actor’s name rather than John because John is not able to represent all the students. That is why we need to name the actor as actor’s role.

Identify – actors

Consider the following requirements:

The customer may choose to order a sofa online or

may through online contact us function to make an request that the salesman contact him/her to explain order details, negotiate the price, etc. before the order is actually placed.

The factory Amin obtains the invoice from the

salesman and pass shipping detail to shipping.com to ships the sofa(s) to the customer.

So the potential actors are : Customer, Salesman, factory and shipping company

What is use-case modelling?

A use-case model describes a system’s functional requirements in terms of use cases.

Links and meets to stakeholders needs to software requirements

Defines clear boundaries of a system

Captures and communicates the desired behaviour of the system

Identifies who or what interacts with the system (actors)

Validates/verifies requirements

It is very powerful planning instrument, it is generally used in all phases of the development cycle by all software development team members.

A use-case model consists of both diagrams and text.

The diagrams give a visual overview of the system.

The text gives descriptions of the actors and the use case

Use cases only deal with Functional requirements

How to create a use-case model

1. Identify actors and use cases in scenario

Define each actor by writing a brief description that includes the actor’s responsibility and what the actor needs from the system for.

2. Write the use cases

Outline all use cases

Prioritize the use-case flows

Detail the flows in order of priority

When actors and use cases have been identified, each use case is described in details which show how the system interacts with the actors and what the system does in each individual case/

Define use case

A use case describes a set of possible executions of the system.

A use case defines a sequence of actions performed by a system that produces an observable result of value to an actor.

How to identify use cases

Use case represents something of value that the system does for its actors.

A use care describes:

The system, its environment and the relationship between them.

How things outside the system interact with the system

The desired behaviour for the system

Tip:

Use case begins with a verb

Indicate the value or goal of the actor

Look all the verbs in your scenario e.g. order, request, print etc.

Identify use cases

Consider the following requirements:

The customer may choose to order sofa(s) online or

may through online contact us function to make an request that the salesman contact him/her to explain order details, negotiate the price, etc. before the order is actually placed.

The factory Admin obtains the invoice from the salesman and ships the sofa(s) to the customer.

Order sofa(s)

Request Print Invoice

Request Salesman Contact

Communicates-Associations in use-case diagram

A channel of communication between an actor and a use case.

Relationships between actors and used cases are called communicates-associations.

A line is used to represent a relationship between actors and use cases.

An arrowhead is used to indicate who initiated the interaction

No arrowhead indicates either end can initiate each interaction.

Example of Communicates-Associations

Actor: customer always initiates communication with the system.

The system may respond to messages from actor: customer but can never send an unsolicited message to customer., the system always initiated communication with Actor: shipping company.

Actor: shipping company may respond to message to the system, but can never send an unsolicited message to the system. For the actor: salesman or the system may initiate the dialog.

Activity diagram – actions

Actions : Process Order sofa(s)

1. Get Purchase Store Order:

The Customer searches and then chooses the Purchase function to submit his/her order to the funiture4u.com website.

2. Store Order:

The system assigns a unique order number to the customer and links to the customer account number to the purchase order.

The order system will store the order’s details in the database.

3. Email the customer his/her ordering details

The system automatic send e-mails to the Customer the Ordering Details which include the unique order number and the customer ID, total cost etc. as the confirmation of the order’s acceptance.

P.S. If the customer didn’t find what he/she looking for or the item is not available, the system should give the customer another choice or to close the search.

Class attributes

The structure of a class is defined by its attributes. Without attributes, we can’t store the data in the class. Finding meaningful and useful attributes are important. In practice, the main attributes are usually allocated to a class immediately after the class has been added to the model.

Tips for finding attributes

Most attributes can be found from user requirements and from the domain knowledge.

Step1 : work on defining identifying attributes for each class.

Step 2: one ore more attributes in a class that have unique values across all instances of the class. E.g. orderID. It is called primary key or class key. Ideally, a primary key should consist of one attribute.

What is class diagram?

Following the approach taken in finding actors and use cases, activity diagram, now we can construct a class diagram from the analysis of functional requirements.

Entity classes define the functional requirements in software system.

In class diagram, it includes class name, attributes and relationship between classes and operations/methods.

Tips for finding classes

Finding classes is an interactive tasks.

Step 1: list the initial list of possible candidate classes (check the actors, sometimes actors can be your classes)

Step 2: Is the concept a container for data?

Step 3: does it have separate attributes that will take on different values?

Step 4: would it have many instance objects?

Step 5: Is it in the scope of the application domain?

Class Diagram

Associations between classes establish pathways for easy object collaboration.

Graphically, a class is represented as a rectangle with three compartments. From the top to the bottom compartments which are class name, class attributes and class operations/methods.

Customer class’s attributes:

cId: String

cName: String

cAddress: String

cPhoneNumber: String

cEmail:String

Etc…

order class’s attributes:

orderID: String

totalCost: float

orderDate: Date

shippingStatus: String

orderPaid: Boolean

Etc…

furniture class’s attributes:

furnitureID: String

furnitureName: String

furnitureDescription:String

cost: float

colour: String

Fibre: String

Style: String

Etc…

Orderlist class’s attributes:

orderListID: String

orderListName: String

cost: float

itemName: String

itenId: String

itemDescription: String

cId: String

Etc…

Computer architecture

“An architectural model for distributed systems where the system functionality is offered as set of services provided by a server. There ae accessed by client computers that make use of the services. Variants of this approach, such as three-tier client-server architectures, use multiple servers.” (Sommerville, 2011, pp.736)

Components

A set of standards for component implementation, documentation and deployment. These cover the specific interfaces that may be provided by a component, component naming, component interoperation, and component composition. Component models provide the basis for middleware to support executing components.

Component is a deployable, independent unit of software that is completely defined and accessed through a set of interfaces.

A

abstract class

A class that can be used only as a superclass of some other class; no objects of an abstract class may be created except as instances of a subclass.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.615

Activity diagram

Activity diagrams/ flow charts are useful tool which it can be use to describe a use case too.

Data source: lecture notes

Actor

Actor represents a role that interacts with the system.

Data source: lecture notes

actor role

A named end of an association to indicate its purpose

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.618

aggregation

A property of an association representing a whole-part relationship and (usually) life-time containment.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.615

association

A description of a related set of links between objects of two classes.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.615

attribute

A named characteristic or property that is the same for all instances of a class. This information is usually stored in the class definition.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.615

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C

class

In the UML , "The descriptor of a set of objects that share the same attributes, operations, methods, relationships, and behaviour. May be used to represent software or conception elements.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.615

class diagram

A UML diagram types that shows the object classes in a system and their relationships. Entity classes define the functional requirements in software system.

Data source: Sommerville I. 2016"Software Engineering" 10th Edition. Pearson Pp.759

Client-Server architecture

An architectural model for distributed systems where the system functionality is offered as set of services provided by a server. There ae accessed by client computers that make use of the services. Variants of this approach, such as three-tier client-server architectures, use multiple servers.

Data source: Sommerville I. 2016"Software Engineering" 10th Edition. Pearson Pp.760

collaboration

Two or more objects that participate in a client/server relationship in order to provide a service.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.615

communicates-associations

Relationships between actors and used cases are called communicates-associations.

Data source: Lecture notes

component

A deployable, independent unit of software that is completely defined and accessed through a set of interfaces.

Data source: Sommerville I. 2016"Software Engineering" 10th Edition. Pearson Pp.760

component model

A set of standards for component implementation, documentation and deployment. These cover the specific interfaces that may be provided by a component, component naming, component interoperation, and component composition. Component models provide the basis for middleware to support executing components.

Sommerville I. 2016"Software Engineering" 10th Edition. Pearson Pp.760

composition

The definition of a class in which each instance is comprised of other objects.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.616

concept

category of ideas or things. It used to designate real-world things rather than software entities. A concept's intension is a description of its attributes, operations and semantics. A concept's extension is the set of instances or example objects that are members of the concept. Often defined as a synonym for domain class.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.616

conceptual design

The development of a high-level vision of a complex system and a description of its essential capabilities. Designed to be understood by people who are not system engineers.

Data source: Sommerville I. 2016"Software Engineering" 10th Edition. Pearson Pp.761

concrete class

A class that can have instances

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.616

constraint

A restriction or condition on an element.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.616

coupling

A dependency between elements (such as classes, packages, subsystems), typically resulting from collaboration between the elements to provides a service.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.616

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D

design

A process that uses the products of analysis to produce a specification for implementation details of some element, such as an object or subsystem. All interaction with an object is through a public interface of operations.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.616

domain

A formal boundary that defines a particular subject or area of interest.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.616

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E

end user

That stakeholder group which uses an information system to conduct work

Data source: Beynon-Davies p, 2002 "Information systems: An introduction to informatics in organisations" , 1st Edition, Palgrave. pp.564

event

A noteworthy occurrence

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.616

Experiments

designed in terms of hypothesised relationships between independent variables (Those presumed to cause certain phenomena) and dependent variables (those presumed to indicate the presence of certain effects). To study these relationships closely all other variation in the environment has to be controlled.

Data source: Beynon-Davies p, 2002 "Information systems: An introduction to informatics in organisations" , 1st Edition, Palgrave. pp.564

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F

Framework

A set of collaborating abstract and concrete classes that may be used as a template to solve a related family of problems. It is usually extended via subclassing for application specific behaviour.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.616

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G

generalisation

The activity of identifying commonality among concepts and defining a superclass (general concept), and subclass (specialised concept) relationships. IT is a way to construct taxonomic classifications among concepts which are then illustrated in class hierarchies. Conceptural subclasses conform to conceptual superclasses in terms of intension and extension.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.616

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I

inheritance

A feature of object-oriented programming languages by which classes may be specialised from more general superclasses. Attributes and method definitions from superclasses are automatically acquired by the subclass.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.617

interface

A set of signatures of public operations

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.617

interview

The research technique is frequently used as a means of gaining an in-depth appreciation of some phenomena. Interviews essentially involve either a structured or unstructured discussion with some person(s) on a certain topic.

Data source: Beynon-Davies p, 2002 "Information systems: An introduction to informatics in organisations" , 1st Edition, Palgrave. pp.564

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L

link

A connection between two objects; an instance of an association.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.617

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M

method

In the UML the specific implementation to algorithm of an operation for a class. Informally, the software procedure that can be executed in response to a message.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.617

model

A description of static and/or dynamic characteristics of a subject area, portrayed through a number of views (usually diagrammatic or textual)

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.617

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O

object class

An object class defines that attributes and operations of objects. Objects are created at run-time by instantiating the class definition. The object class name can be used as a type name in some object-oriented language.

Data source: Sommerville I. 2016"Software Engineering" 10th Edition. Pearson Pp.766

object model

A model of a software system that is structured and organised as a set of object classes and the relationships between these classes. Various different perspectives on the model may exist such s a state perspective and a sequence perspective.

Data source: Sommerville I. 2016"Software Engineering" 10th Edition. Pearson Pp.766

object-oriented (OO) development

An approach to software development where the fundamental abstractions in the system are independent objects. The same type of abstraction is used during specification, design and development

Data source: Sommerville I. 2016"Software Engineering" 10th Edition. Pearson Pp.766

observation

This research technique is important as a means of gaining detailed data on what people actually do. The observer may participate in the activities of the observed group or be independent of these activities. Observation may also be explicit or illicit.

Data source: Beynon-Davies p, 2002 "Information systems: An introduction to informatics in organisations" , 1st Edition, Palgrave. pp.564

OID

Object Identifier

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.617

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P

pattern

A pattern is a named description of a problem, solution, when to apply the solution, and how to apply the solution in new contexts.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.617

postcondition

A constraint that must hold true after the completion of an operaton.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.622

precondition

A constraint that must hold true before an operation is requested

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.618

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R

requirement management

The process of managing changes to requirements to ensure that the changes made are properly analysed and tracked through the system.

Data source: Sommerville I. 2016"Software Engineering" 10th Edition. Pearson Pp.769

requirement, functional

a statement of some function or feature that should be implemented in a system.

Data source: Sommerville I. 2016"Software Engineering" 10th Edition. Pearson Pp.769

requirement, non-functional

A statement of a constraint or expected behaviour that applies to a system. This constraint may refer to the emergent properties of the software that is being developed or to the development process.

Data source: Sommerville I. 2016"Software Engineering" 10th Edition. Pearson Pp.769

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S

scenario

A description of one typical way in which a system is used or a user carries out some activity.

Data source: Sommerville I. 2016"Software Engineering" 10th Edition. Pearson Pp.770

scenario testing

An approach to software testing where test cases are derived from a scenario of system use.

Data source: Sommerville I. 2016"Software Engineering" 10th Edition. Pearson Pp.770

sequence diagram

A diagram that shows the sequence of interactions required to complete some operation. In the UML, sequence diagrams ma be associated with use cases.

Data source: Sommerville I. 2016"Software Engineering" 10th Edition. Pearson Pp.771

stakeholder

The group of people to which an information system is relevant

Data source: Beynon-Davies p, 2002 "Information systems: An introduction to informatics in organisations" , 1st Edition, Palgrave. pp.591

stakeholder analysis

Analysing the types of and impact of stakeholders on information systems

Data source: Beynon-Davies p, 2002 "Information systems: An introduction to informatics in organisations" , 1st Edition, Palgrave. pp.591

stakeholder involvement

Involvement of stakeholder representatives in the development of an IT system.

Data source: Beynon-Davies p, 2002 "Information systems: An introduction to informatics in organisations" , 1st Edition, Palgrave. pp.591

stakeholder participation

involvement of stakeholders both in the development of the IT system and the work surrounding its use.

Data source: Beynon-Davies p, 2002 "Information systems: An introduction to informatics in organisations" , 1st Edition, Palgrave. pp.591

stakeholder resistance

The resistance of stakeholder groups to the introduction of some information system

Data source: Beynon-Davies p, 2002 "Information systems: An introduction to informatics in organisations" , 1st Edition, Palgrave. pp.591

stakeholder satisfaction

The state of satisfaction expressed by some stakeholder group in an information system

Data source: Beynon-Davies p, 2002 "Information systems: An introduction to informatics in organisations" , 1st Edition, Palgrave. pp.591

state

The condition of an object between events.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.618

subclass

A speciatlisation of another class (the supperclass). A subclass inherits the attributes and methods of the superclass.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.618

superclass

A class from which another class inherits attributes and methods.

Data source: Larman c. 2002 "Applying UML and Patterns", 2nd, Pearson. Pp.619

system

A system is a purposeful collection of interrelated components, of different kinds, which work together to deliver a set of services to the system owner and users.

Data source: Sommerville I. 2016"Software Engineering" 10th Edition. Pearson Pp.772

system engineering

A process that is concerned with specifying a system, integrating its components and testing that the system meets its requirements. System engineering is concerned with the whole socio-technical system-software, hardware and operational process-not just the system software.

Data source: Sommerville I. 2016 "Software Engineering" 10th Edition. Pearson Pp.772-773

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U

unified modelling language(UML)

A graphical language used in object-oriented development that includes several types of system models that provide different views of a system. The UML has become a de facto standard for object-oriented modelling.

Data source: Sommerville I. 2016"Software Engineering" 10th Edition. Pearson Pp.773

use case

"Use case represents something of value that the system does for its actors. A use case defines a sequence of actions performed by a system that produces an observable result of value to an actor."

Data source: Sommerville I. 2016"Software Engineering" 10th Edition. Pearson Pp.773

use-case modelling

A use-case model consists of both diagrams and text. The text gives descriptions of the actors and the use case.

Data source: Sommerville I. 2016"Software Engineering" 10th Edition. Pearson Pp.773

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V

validation

The process of checking that a system meets the needs and expectations of the customer.

Data source: Sommerville I. 2016"Software Engineering" 10th Edition. Pearson Pp.774

verification

The process of checking that a system meets its specification.

Data source: Sommerville I. 2016"Software Engineering" 10th Edition. Pearson Pp.774

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