Information technology solutions development

Fundamentals of Information TechnologySession 3

The systems development lifecycle

• IT systems development can be viewed as a linear (waterfall) process from analysis through to maintenance

• However, this model of development is really simplification and an idealisation of the development process used mainly for descriptive purposes

• In reality, development tends to be iterative and/or incremental, using a prototyping rather than a linear approach

Analysis

Design

Implementation

Testing

Maintenance

The systems development lifecycle – Prototyping

• Prototyping is the process of quickly putting together a working model in order to test a design, and get early user feedback

• Successive prototypes are created in a process of iterative and incremental development until a satisfactory and robust product emerges

• This means that problems or deficiencies in design can be corrected early in the development process and requirements can be refined and/or added as development proceeds

The systems development lifecycle – Prototyping

Analysis

DesignImplementation

TestingAnalysis

DesignImplementation

TestingAnalysis

DesignImplementation

Testing

iterative

Prototype 1Main functionality only implemented

Prototype 2Most functionality

implemented

Beta versionAll functionalityimplemented

The systems development lifecycle

• Each stage of the development process includes a set of related sub-processes and activities

(4) Systems Testing

Improved protoype

(3) Systems implementation

Prototype

(2) Systems design

Product specification

(1) Systems analysis

Requirements statement

(1) Conduct feasibility study(2) Analyse user requirements(3) Develop user requirements statement

(1) Evaluate different solutions(2) Develop design specifications for hardware, software, network components

(1) Build hardware platform(2) Develop or purchase software(3) Integrate software and hardware

(1) Release system(2) Test system(3) Make necessary optimisations

Systems analysis – feasibility

• The possible benefits and achievability of proposed IT solutions are normally expressed in a feasibility study

• A feasibility study examines the business, technical and case for building a new system

• Business case – By how much will the proposed product reduce costs?– By how much will the product increase profit?– How will it enhance competitive advantage?

• Technical case– Does the organisation have in-house expertise, or will it have

to procure bought-in development resources, or outsource?• Organisational

– What training needs will there be?– What is the potential for stakeholder resistance? – What are the legal ramifications?

Systems analysis – requirements specification

• Systems analysis can best be viewed as a statement of a problem (not the solution) that constitutes a need for organisational change

• Systems analysis generally involves a series of distinct activities1. An analysis of the strengths and weaknesses of the current

system, culminating in a statement detailing where the system can be improved

2. Development of a requirements specification for the new system showing the – functional requirements (What a new system should do), – data requirements (What data load a new system needs to be

able to manage) – non-functional requirements (The level to which a new system

is expected to perform)

3. Definition of constraints (e.g. economic, technical, organisational factors limiting the development of the system)

Systems analysis – requirements specification

• Functional requirements detail the required behaviours of a system (e.g. what the user can do with the system)

• They are discovered through dialogue with end-users, stakeholders and information experts within an organisation in workshops, interviews or questionnaires

• Individual requirements are generally specified using the following format: X should/shall/must do Y . – The system should allow the administrator to set up user

accounts – The system shall prompt users to change their passwords

every six weeks – The system must provide clear feedback that a password has

been successfully changed

Systems analysis – requirements specification

• Data requirements determine:– The kind of data a system will hold (e.g. customer

accounts, orders, products, etc.) – The quantity of data that a system will have to store – The system should hold records of all orders placed

within the past ten years – The system must be able to provide storage for the

personal details of up to 1 million customers

Systems analysis – requirements specification

• Non-functional requirements detail requirements related to system performance and evolution. They will specify factors such as:– Usability– Accessibility– Security– Extensibility/Scalability– Performance (e.g. response time)

– The system shall allow for 200 concurrent users with no loss of performance

– The system must provide interfaces that are accessible regardless of ability or disability

Systems analysis – constraints

• Constraints specify parameters in which the system should be built and operate

• These parameters can be: legal, technical, economic, social, etc.

– The system must be operational within eighteen months– The system should satisfy all requirements under

copyright law– The system must be built for less than £200,000

System design

• System design provides the solution to the problem specified in the systems analysis stages of development

• It involves three distinct activities

Process design

Interface design

Data design

System design – process design

• Process design focuses on modelling the path of data and transition as it moves through the system

• Multiple techniques are available for process modelling, such as: – Flowcharts

– SSADM (Structured System Analysis and Design Method)– UML (Unified modelling language)

• http://www.uml.org/

Add to basketProceed to ckeckout?

Select Product yes

no

Checkout

System design – data design

• Data design specifies the data objects (entities) that will be stored in the system

• It also specifies the relationships between the data types

Customer Order Product

Customer Order ProductPlaces Contains

System design – data design

• And the attributes that the data types have

Customer

Customer_IDCustomer_NameAddress_1Address_2CityCountryTelephoneEmail

Product

Product_IDProduct_NameDescriptionPriceSupplier

System design – interface design

• Interface design involves designing the part of the system the end-user will interact with

• It involves designing dialogues (user instructions), menus, toolbars, etc.

• Interface design is done using storyboards or wireframes.

System design – interface design

• Example storyboards

Implementation

• System Implementation takes the design specifications from the design phase and turns them into concrete products

• Implementation should follow a strict process from the development of the software, through testing, to release

Loading/testing of software on

hardware platform

Development/acquisition of

software

Acquisition of hardware platform

Data migration

Testing

End-user training

Beta/end-user testing

Implementation

• The final stage of implementation is release• Release of new IT systems can follow several scenarios

• Each scenario entails varying degrees of risk. However, some entail more risk than others.

Old System

New system Parallel

Old System New System Pilot

Old System New System Phased

New systemOld System Plunge

FIT Session 3 – Activities

• Now do – Activity 3 – IT solutions development