lecture 4 web information system development methodolog y

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Lecture 4

WEB Information System Development Methodology

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Information Systems

Set of interacting components (people, procedures, technologies) that

together collect, process, store and distribute information

to support control, decision-making and management in organizations.

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Information Systems

Key components of Information Systems

Organizations Human Technologies

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Information Systems

Developments in In

formation and Communication technologies

Paper-based IS

Computer-based IS

WEB-based IS

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Why IS Development Methodologies

Average completion time for IS projects: 1.5 -5 years

68% of projects overrun schedules

65% exceed budgets

75% face major redesign after initial implementation

Solution lies in better and more professional approaches to development.

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Why IS Development Methodologies

A methodical approach to software development results in fewer defects and, therefore, ultimately provides shorter delivery times and better value.

Remember:Remember:

Goal => High qualityGoal => High quality

High quality = project timelinessHigh quality = project timeliness

Less rework!Less rework!

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Some Terminologies

Software development methodology Software development process Software development model Software life-cycle Software process model

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What is IS Development Methodology

A collection of procedures, techniques, tools and documentation aids which helps the system developers in their effort to implement a new information system.

Software Engineering

a “quality” focusa “quality” focus

process modelprocess model

methodsmethods

toolstools

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IS Development Methodologies

A methodology consists of phases, themselves consisting of sub-phases, which

• help developers plan, manage, control and evaluate IS projects,

• guide developers in their choice of techniques at each stages of the projects.

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Benefits of IS Development Methodologies

Subdivision of complex process into small tasks.

Facilitation of project management and control. Providing a framework for applying techniques. Skill specialization and division of labor Standardization, improving productivity and

quality.

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There are a lot of process models, and many companies adopt their own, but all have very similar patterns. The general, basic model is shown below:

The General Process Model

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• Business requirements are gathered in this phase.

• Who is going to use the system? • How will they use the system? • What data should be input into the system? • What data should be output by the system?

• This produces a nice big list of functionality that the system should provide, which describes functions the system should perform, business logic that processes data, what data is stored and used by the system, and how the user interface should work.

Requirements

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• The software system design is produced from the results of the requirements phase.

• This is where the details on how the system will work is produced.

• Architecture, including hardware and software, communication, software design are all part of the deliverables of a design phase.

Design

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• Code is produced from the deliverables of the design phase during implementation, and this is the longest phase of the software development life cycle.

• For a developer, this is the main focus of the life cycle

because this is where the code is produced.

• Implementation my overlap with both the design and testing phases.

• Many tools exists (CASE tools) to actually automate the production of code using information gathered and produced during the design phase.

Implementation

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• During testing, the implementation is tested against the requirements to make sure that the product is actually solving the needs addressed and gathered during the requirements phase.

• Unit tests and system/acceptance tests are done during this

phase.

• Unit tests act on a specific component of the system, while system tests act on the system as a whole

Testing

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Life-Cycle of a Software

Feasibility

Requirements

Design

Coding

Testing

Operations

Maintenance

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Umbrella Activities

Software project management Software quality assurance Software configuration management Reusability management Risk management

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IS Process Models

Waterfall model Evolutionary model Iterative/incremental model

Spiral model V-model Prototyping Agile software development Clean room Software Engineering Component Assembly Model Rational Unified Process

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Waterfall model

Waterfall

• Systematic stepwise refinement of a complex problem into smaller and smaller problems.

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Waterfall model

Requirements

definition

System andsoftware design

Implementationand unit testing

Integration andsystem testing

Operation and

maintenance• Requirements analysis and definition• System and software design• Implementation and unit testing• Integration and system testing• Operation and maintenance

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Waterfall model

The main drawback of the waterfall model is the difficulty of accommodating change after the process is underway. One phase has to be completed before moving onto the next phase.

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Waterfall model problems

Inflexible partitioning of the project into distinct stages makes it difficult to respond to changing customer requirements.

Therefore, this model is only appropriate when the requirements are well-understood and changes will be fairly limited during the design process.

Few business systems have stable requirements.

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Evolutionary development

Evolutionary

• System is developed using a prototype and refined through user feedbacks.

• Changes is seen as the norm of the model.

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Communication

Quick plan

Construction of prototype

Modeling Quick design

Delivery & Feedback

Deployment

requirements

Quickplan

ModelingQuick design

Constructionof prototype

Deploymentdelivery &feedback

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Concurrentactivities

ValidationFinal

version

DevelopmentIntermediate

versions

SpecificationInitial

version

Outlinedescription

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Exploratory development • Objective is to work with customers and to evolve

a final system from an initial outline specification. Should start with well-understood requirements and add new features as proposed by the customer.

Throw-away prototyping• Objective is to understand the system

requirements. Should start with poorly understood requirements to clarify what is really needed.

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Problems• Lack of process visibility;• Systems are often poorly structured;• Special skills may be required.

Applicability• For small or medium-size interactive systems;• For parts of large systems (e.g. the user

interface);• For short-lifetime systems.

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Iterative / incremental

Iterative Development

• System is developed in chunks of functionality.

• The overall system is developed incrementally.

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C o m m u n i c a t i o n

P l a n n i n g

M o d e l i n g

C o n s t r u c t i o n

D e p l o y m e n t

d e l i v e ry f e e d b a c k

analys is

des ign code

t es t

increment # 1

increment # 2

delivery of 1st increment

delivery of 2nd increment

delivery of nth increment

increment # n

project calendar time

C o m m u n i c a t i o nP l a n n i n g

M o d e l i n g


De p l o y m e n t

d e l i v e r y

f e e d b a c k

analys is

des ign code

t es t

C o m m u n i c a t i o nP l a n n i n g

M o d e l i n g


D e p l o y m e n t

d e l i v e r y

f e e d b a c k

analys is

des igncode t es t

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Advantages Generates working software quickly and early during the

software life cycle. More flexible – less costly to change scope and requirements. Easier to test and debug during a smaller iteration. Easier to manage risk because risky pieces are identified and

handled during its iteration. Each iteration is an easily managed milestone.

Disadvantages Each phase of an iteration is rigid and do not overlap each

other. Problems may arise pertaining to system architecture because

not all requirements are gathered up front for the entire software life cycle.

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Spiral model

Riskanalysis

Riskanalysis

Riskanalysis

Riskanalysis Proto-

type 1

Prototype 2

Prototype 3Opera-tionalprotoype

Concept ofOperation

Simulations, models, benchmarks

S/Wrequirements

Requirementvalidation

DesignV&V

Productdesign Detailed

design

Code

Unit test

IntegrationtestAcceptance

testService Develop, verifynext-level product

Evaluate alternatives,identify, resolve risks

Determine objectives,alternatives and

constraints

Plan next phase

Integrationand test plan

Developmentplan

Requirements planLife-cycle plan

REVIEW

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V-Model

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Web Design and Development

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Developments in Information Systems:

Information systems are entering a new phase, moving beyond the traditional automation of routine organizational processes and towards the existing of critical tactical and strategic enterprise processes.

Development of such systems needs to concentrate on organizational aspects , delivering systems that are closer to the culture of organizations and the wishes of individuals.

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Where are we with web application design methods?

• It’s a relatively new area, most significant work only emerged from 1993 onwards

• Very much in the infancy stages• No one solid method has emerged• Few approaches have been severely tested• We have most methods and technique components

we need in existence for a web method, in almost all cases though they have just not been integrated

• So, currently we need to work around the issue by forming ‘hybrid’ methods that share and borrow techniques

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Web Methodology Disciplines

Web Engineering

Hypertext

InformationEngineering

RequirementsEngineering

System Analysisand Design

Multimedia

Human-ComputerInteraction

Testing

Project Management

SoftwareEngineering

Modellingand Simulation

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Special features of Web Projects

Network intensiveness Concurrency Unpredictable load Performance. Availability Data driven. Content sensitive. Continuous evolution Immediacy Security Aesthetics

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Alternatives for WEB IS acquisition

In-house development Outsourcing

• Development of IS• Application service providers

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A strategy to Web IS development

Introduce WISDM to • offer a methodology for the socio-technical view;• illustrate a socio-technical framework.

Use the RUP as powerful generic framework that can be flexibly taylored and extended by special techniques to suit the particular project.

Introduce various techniques to complement RUP activities in order to better address the specific features of Web-IS such as• User-orientation, broad view on requirements, specific

architectural patterns, graphic design, navigation, etc.

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The Multiview Approach and WISDM

Multiview‘s fundamental assumption: An IS methodology that relies overmuch on an engineering approach and technical rationality is, by itself, an insufficient foundation for IS development.

Foundations of Multiview: Needs of computer artefacts, organizations and individuals need to be considered jointly!

Major concern of Multivies: Negotiation between technological, organizational, and human aspects of IS development.

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WISDM

IS DEVELOPMENT METHODS

CHANGE AGENTSMultiple perspectives:•Technical (T)•Organizational (O)•Personal (P)

SITUATION

History

Would-be developers of an information system

WISDM - Web IS Development Methodology(emergent)

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WISDM as emerging methodology from the Multiview framework

Situation Developers

TechnologyOrganisationHumans

WorkDesignUsersatisfaction

TechnicalDesign

Softwaremodel

HCI

User interface

OrganizationalAnalysisValue creation(human activity systems)

InformationAnalysis

Requirementsspecification

SO

CIO

TE

CH

NIC

AL

ANALYSIS

DESIGN

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WISDM Methods matrix and role of the analyst

There is no a priori ordering of the five apects of the WISDM matrix

Essential aspect: Analyst works on the joint basis of the three (T, O, P) perspectives.

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Organizational Analysis


TechnicalDesign

Softwaremodel

HCI

User interface


InformationAnalysis


SO

CIO

TE

CH

NIC

AL

ANALYSIS

DESIGN

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Organizational Analysis

Business (strategy)• What business is the Organization in?

• What are the products and services? Products and services

• What are the sources of revenue?

• What are the benefits to the business actors? Who are the customers? Who are the competitors? Marketing strategy (How to compete)

• What is the organization’s marketing strategy?

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Work design


TechnicalDesign

Softwaremodel

HCI

User interface


InformationAnalysis


SO

CIO

TE

CH

NIC

AL

ANALYSIS

DESIGN

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Sociotechnical design

Foundation: Genuine participation:involves users, managers, developers, and others who influence each other‘s plans policies and decisions, thus affecting future outcomes.

Measure user satisfaction and quality.

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Quality workshop, WebQualCategory WebQual 4.0 Questions

Usability

Information

Service Interaction

Overall

1. I find the site easy to learn to operate2. My interaction with the site is clear and understandable3. I find the site easy to navigate4. I find the site easy to use5. The site has an attractive appearance6. The design is appropriate to the type of the site7. The site conveys a sense of competency8. The site creates a positive experience for me9. Provides accurate information10. Provides believable information11. Provides timely information12. Provides relevant information13. Provides easy to understand information14. Provides information at the right level of detail15. Presents the information in an appropriate format16. Has a good reputation17. It feels safe to complete transactions18. My personal information feels secure19. Creates a sense of personalization20. Conveys a sense of community21. Makes it easy to communicate with the organization22. I feel confident that goods/services will be delivered as promised23. My overall view of this website

(Vidgen, Tab. 7-4)

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Quality workshop, WebQual

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Technical Development


TechnicalDesign

Softwaremodel

HCI

User interface


InformationAnalysis


SO

CIO

TE

CH

NIC

AL

ANALYSIS

DESIGN

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Information Analysis

Elements of the analysis model• Data model• Flow model• Class model• Behavior model

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Technical Design

Elements of the design model• Data design• Architectural design• Component design• Interface design• Aesthetic design• Navigation design

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The Rational Unified Process RUP is an iterative software development process framework

created by the Rational Software Corporation, a division of IBM since 2002.

It has an underlying object-oriented model, using Unified Modeling Language (UML).

RUP is based on a set of six key principles:• Adapt the process • Balance stakeholder priorities • Collaborate across teams • Demonstrate value iteratively • Elevate the level of abstraction • Focus continuously on quality

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Rational Unified Process Model

Phase iteration

Inception Elaboration Construction Transition

Inception : Establish the business case for the system. Elaboration : Develop an understanding of the problem

domain and the system architecture. Construction : System design, programming and testing. Transition : Deploy the system in its operating environment.

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RUP Phases

• Inception is concerned with determining the scope and purpose of the project;

• Elaboration focuses requirements capture and determining the structure of the system;

• Construction's main aim is to build the software system;

• Transition deals with product installation and rollout.

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Size of square relative to time spent on workflows

Inception Elaboration Construction Transition

Project Phases

1 2 3 4 5 6 7 8Iterations within each phase

Requirements

Design

Implementation

Test

Workflows

RUP Phases

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SampleUP Disciplines

Business Modeling

Requirements

Design

Implementation

...

incep-tion

elaboration constructiontransi-

tion

...

RUP Phases

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RUP Phases

software increment

Release

refactoring

business analysis formulation

iteration plan

analysis model content iteration function configuration

design model content architecture navigation interface

coding component test

acceptance test customer use

customer evaluation

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6 UP Best Practices that particularly apply to web-based systems

Develop iteratively Manage and trace requirements Utilize component architectures Model visually Verify quality Control changes

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WUP – Complementing the RUP

For each phase:

Inputs for each phase and iteration of the RUP

UP–activities Web–specific activities

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WUP – Initial tasks

Discuss the topic of your web application and corresponding visions with stakeholders.

Decide which techniques/views (from the RUP or web-specific) may be useful in your special case.

Make a gross plan for the whole development cycle. Make a detailed plan for the next phase. Keep to RUP‘s phase structure and workflows but

vary the specific techniques and views found relevant.

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User requirements

System Model

• Use Case diagram • Activity diagram• Interaction Diagrams

• Sequence diagram • Collaboration diagram

• Class diagram • State diagram • Component diagram • Deployment diagram

An Object-Oriented Technique (UML)

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Unified Modeling Language (UML)

Object Oriented Analysis and Design

The Unified Modeling Language (UML) is a standard language for specifying, visualizing, constructing, and documenting the artifacts of software systems, as well as for business modeling and other non-software systems.

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Use Case Diagram

• A use case is a set of scenarios that describing an interaction between a user and a system.

• A use case diagram displays the relationship among actors and use cases.

• The two main components of a use case diagram are use cases and actors.

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Use Case Diagram

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Sequence Diagrams

Interaction diagrams model the behavior of use cases by describing the way groups of objects interact to complete the task. The two kinds of interaction diagrams are sequence and collaboration diagrams. They demonstrate how the objects collaborate for the behavior.

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Sequence Diagrams

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Sequence Diagram

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Collaboration Diagram

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Collaboration Diagram

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Class Diagrams

Class diagrams are widely used to describe the types of objects in a system and their relationships. Class diagrams model class structure and contents using design elements such as classes, packages and objects

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Class Diagrams

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State Diagrams

• State diagrams are used to describe the behavior of a system.

• State diagrams describe all of the possible states of an object as events occur.

• Each diagram usually represents objects of a single class and track the different states of its objects through the system.

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State Diagrams

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Activity Diagrams

• Activity diagrams describe the workflow behavior of a system.

• Activity diagrams are similar to state diagrams because activities are the state of doing something.

• The diagrams describe the state of activities by showing the sequence of activities performed.

• Activity diagrams can show activities that are conditional or parallel.

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Activity Diagrams

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Deployment Diagrams

• The deployment diagram contains nodes and connections.

• A node usually represents a piece of hardware in the system.

• A connection depicts the communication path used by the hardware to communicate and usually indicates a method such as TCP/IP.

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• The diagram shows two nodes which represent two machines communicating through TCP/IP.

• Component2 is dependant on component1, so changes to component 2 could affect component1.

• The diagram also depicts component3 interfacing with component1.

Combined deployment and component diagram

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Software Requirement Specification (example)

TABLE OF CONTENTSExecutive SummaryI. PROJECT SCOPEII. REQUIREMENTS DEFINITION

2.1 END-USER BUSINESS FUNCTIONALITY2.2 USE-CASES FUNCTIONALITY2.3 WORKFLOWS/BUSINESS PROCESSES2.4 NON-FUNCTIONAL REQUIREMENTS2.5 DERIVED AND IMPLICITE REQUIREMENTS2.6 INTERFACE REQUIREMENTS2.7 REQUIREMENTS SPECIFICATIONS

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Design Document (example)

TABLE OF CONTENTSExecutive Summary IV1. INTRODUCTION2. DESIGN OF THE FOOD SYSTEM

2.1 Modular Structure of the System2.2 Menu Structures2.3 Modules detailed design

2.3.1 Create Class (Module 1.2.1)2.3.2 Update Class (Module 1.2.2)…..

2.4 System Topology2.5 Solutions for additional Requirements

2.6.1 Error handling2.6.2 Database catalog design2.6.3 Connections to other systems

2.6 Data dictionary3. INTERFACE DESIGN4. CONCLUSION

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Web Design Pyramid

Interface design

Aesthetic design

Content design

Navigation design

Architecture design

Component design

user

technology

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End of Lecture 4

lecture 4 web information system development methodolog y

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