software engineering the multiview approach and wisdm
DESCRIPTION
TRANSCRIPT
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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
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:
Goal => High quality
High quality = project timeliness
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” focus
process model
methods
tools
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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
Cleanroom 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 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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Evolutionary development
Communicat ion
Quick p lan
Const ruct ion
of
prot ot ype
Mod e ling
Qu ick de sig n
De live ry
& Fe e dback
Deployment
requirements
Quickplan
ModelingQuick design
Constructionof prototype
Deploymentdelivery &feedback
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Evolutionary development
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Evolutionary development
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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Evolutionary development
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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Iterative Development
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 r y
f e e d b a c k
analy s is
des ign c ode
t es t
increment # 1
increment # 2
delivery of
1st increment
delivery of
2nd increment
delivery of
nt h increment
increment # n
project calendar t ime
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 r y
f e e d b a c k
analy s is
des ign c ode
t es t
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 r y
f e e d b a c k
analy s is
des ignc ode
t es t
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Iterative Development
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
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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)
Organizational
Analysis
Work
Design
Information
Analysis
Technical
DesignUser
satisfaction
Value
creation
Requirements
specification
Software
model
ANALYSIS
DESIGN
TE
CH
NIC
AL
User interface
HCI
SO
CIO
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WISDM as emerging methodology
from the Multiview framework
Situation Developers
TechnologyOrganisationHumans
Work
DesignUser
satisfaction
Technical
DesignSoftware
model
HCI
User interface
Organizational
AnalysisValue creation
(human activity systems)
Information
AnalysisRequirements
specification
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
Work
DesignUser
satisfaction
Technical
DesignSoftware
model
HCI
User interface
Organizational
AnalysisValue creation
(human activity systems)
Information
AnalysisRequirements
specification
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
Work
DesignUser
satisfaction
Technical
DesignSoftware
model
HCI
User interface
Organizational
AnalysisValue creation
(human activity systems)
Information
AnalysisRequirements
specification
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 operate
2. My interaction with the site is clear and understandable
3. I find the site easy to navigate
4. I find the site easy to use
5. The site has an attractive appearance
6. The design is appropriate to the type of the site
7. The site conveys a sense of competency
8. The site creates a positive experience for me
9. Provides accurate information
10. Provides believable information
11. Provides timely information
12. Provides relevant information
13. Provides easy to understand information
14. Provides information at the right level of detail
15. Presents the information in an appropriate format
16. Has a good reputation
17. It feels safe to complete transactions
18. My personal information feels secure
19. Creates a sense of personalization
20. Conveys a sense of community
21. Makes it easy to communicate with the organization
22. I feel confident that goods/services will be delivered as promised
23. My overall view of this website
(Vidgen, Tab. 7-4)
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Quality workshop,
WebQual
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Technical Development
Work
DesignUser
satisfaction
Technical
DesignSoftware
model
HCI
User interface
Organizational
AnalysisValue creation
(human activity systems)
Information
AnalysisRequirements
specification
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 phaseRequirements
Design
Implementation
Test
Workflows
RUP Phases
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Sample
UP Disciplines
Business
Modeling
Requirements
Design
Implementation
...
incep-
tionelaboration construction
transi-
tion
...
RUP Phases
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RUP Phases
sof t ware increment
Release
refact oring
business analysis
formulat ion
it erat ion plan
analysis model
content
iterat ion
funct ion
conf igurat ion
design model
content
architecture
navigat ion
interface
coding
component t est
accept ance t est
cust omer use
cust omer evaluat ion
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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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Technical Development
User
requirementsSystem 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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Technical Development
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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 Summary
I. PROJECT SCOPE
II. REQUIREMENTS DEFINITION2.1 END-USER BUSINESS FUNCTIONALITY
2.2 USE-CASES FUNCTIONALITY
2.3 WORKFLOWS/BUSINESS PROCESSES
2.4 NON-FUNCTIONAL REQUIREMENTS
2.5 DERIVED AND IMPLICITE REQUIREMENTS
2.6 INTERFACE REQUIREMENTS
2.7 REQUIREMENTS SPECIFICATIONS
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Design Document (example)
TABLE OF CONTENTSExecutive Summary IV
1. INTRODUCTION
2. DESIGN OF THE FOOD SYSTEM2.1 Modular Structure of the System
2.2 Menu Structures
2.3 Modules detailed design2.3.1 Create Class (Module 1.2.1)
2.3.2 Update Class (Module 1.2.2)
…..
2.4 System Topology
2.5 Solutions for additional Requirements2.6.1 Error handling
2.6.2 Database catalog design
2.6.3 Connections to other systems
2.6 Data dictionary
3. INTERFACE DESIGN
4. CONCLUSION
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Web Design Pyramid
Interface
design
Aesthetic design
Content design
Navigation design
Architecture design
Component design
user
technology