Transcript Enterprise Web Apps

Web Programming
Methods
What we are going to do…
► Why
methods?
► Traditional method examples
► WSDM
► Conclusion
Methods
► Why
use one?
Methods
► What
it covers
 Possibly all stages
►Feasibility
►Analysis
►Design
►Implementation
►Testing
 Maybe just some of them
►Just
design
Methods
► The
one you do….
►A
method must cover front end design, flow and
database design (as a minimum)
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 rigorously tested
 Is this a problem?
 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
Non Web Methods
► SSADM?
► SSM?
► UML?
► (Look
in Avison / Fitzgerald)
► Suitability for the web?
What is SSADM?
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SSADM (Structured Systems Analysis and Design
Methodology)
used in the analysis and design stages of systems
development. SSADM does not cover Strategic Information
Planning (SITP) issues or the construction, testing and
implementation of software.
"SSADM has been used by the government in computing
since its launch in 1981. It was commissioned by the CCTA
(Central Computing and Telecommunications Agency)
SSADM is an open standard, i.e. it is freely available for use
in industry and many companies offer support, training and
Case tools for it.
Why is SSADM Used?
► Within
government departments SSADM
has to be used? External contractors
producing software for the government also
have to use SSADM?
► SSADM is used by other companies
because they expect the use of a disciplined
‘engineering approach will eventually
improve the quality of the systems they
produce.
How is SSADM Structured?
►
It has seven stages numbered 0 to 6
 Feasibility
►It is technically possible and the benefits of the
information system will outweigh the cost
 Requirements analysis
►Investigation of current environment
 Requirements Specification
►Definition of requirements
 Logical System Specification
►Technical system options and logical design
 Physical design
►Prepare for physical design
►Create physical data design
►Create function component implementation map
►And so on
What is SSM?
► Soft
system Methodology
 Developed as a response to hard systems and
it’s failure to address messy situations.
► Organise
our thinking systemically but
recognising that the perceived is
problematic
Seven stages
The problem situation unstructured .
1.

The first two stages are concerned with finding out
about the problem situation from as many people in
that situation as possible
Problem situation expressed
2.

Expressed in a formal way a method of doing this is to
draw a rich picture of the situation. The rich picture is
used as an aid in discussion between the problem
solver and the problem owner.
3:Root definition of relevant system
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several different relevant systems should be explored to
see which is the most useful.
 At this stage that debate is most important. The
problem owner and problem solver decide which view
to focus on, that is how to describe their relevant
system.
After constructing a rich picture a root definition is
developed for the relevant system. The root definition is a
concise, tightly constructed description of a human
activity system which states what the system is
(Checkland,1981).
Using a CATWOE checklist technique the root definition
is created.
CATWOE
► Clients
-people affected by the system
► Actors -people who are part of the system
► Transformation -the process done by system
► Worldview -describes the system
► Owners -people who affect/kill the system
► Environment -influences the system
4: Building Conceptual models
► When
satisfied that the root definition is well
formed a conceptual model can be
developed
► A conceptual model is a diagram of the
activates showing what the system will do
as described by the root definition
5: Comparing conceptual models
with reality
► Comparison
of the problem situation
analysed in stage 2 through rich pictures
alongside the conceptual models created in
stage 4
► Debate about possible changes should lead
to set of recommendations regarding
change in order to help the problem
6: Assessing feasible and desirable changes
► Concerns
an analysis of proposed changes
from stage 5 so to draw up proposals for
those changes
7:Action to improve problem situation
► Final
stage about recommending action to
help the problem situation
► This type of methodology helps understand
the problem situation rather than a scheme
for solving a particular problem.
Methodology Stage Comparison
SSADM
Strategy
JSD
ETHICS
Some
Feasibility
Yes
Analysis
Yes
Logical Design
Physical Design
SSM
Yes
Some
Some
Some
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Some
Programming
Yes
Testing
Some
Implementation
Some
Evaluation
Little
Little
Maintenance
Adapted from: Avison and Fitzgerald
Information Systems Development: Methodologies, Techniques and Tools, 3rd edn., 2003, Page 568.
Web Methodology Disciplines
Multimedia
Human-Computer
Interaction
Software
Engineering
Web Engineering
Testing
Project
Management
Hypertext
Information
Engineering
Requirements
Engineering
Modelling
and Simulation
System Analysis
and Design
from: Murugesan et al, Web Engineering: A New Discipline for Development of Web-Based Systems, in
“Web Engineering: Managing Diversity and Complexity of Web Application Development, 2001. Page 8
WSDM (pronounced Wisdom)
Web Site Design Method (WSDM)
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Has a focus on designing kiosk web-sites
Systems with many user types / walk up and use
Follows a ‘user centred’ focus rather than ‘data
centred’ (information) approach
To do so need to identify different types of user e.g.
student, prospective student, lecturer, etc.
Then produce a site that is sensitive to the given user
types
May result in different pages or paths being provided
in a site for each type of user
Starts to lay the foundations for the principles of
localization and internationalization
WSDM: Conceptual Design
Mission statement:
• purpose
• target audience
• subject
Mission statement
Specification
Audience Class
Hierarchy
Audience Modeling
Audience
Classification
Audience Class
Description
• Requirements:
Information
Functional
Usability
• Characteristics
Audience Class
Characterization
Conceptual Design
Task Modeling
Navigational
Design
Author
Implementation design
Page
Design
Presentation
Design
Visitor
Data
Design
PC-Chair
Object Chunk C1
Reviewe
Track
(Name)
Subject
(Name)
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{*s} -> ??
of
/for
PC-Member
Date
(dd/mm/yyyy)
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File
(URL)
Implementation
Paper
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Abstract
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© Prof. Dr. Olga De Troyer 2002
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Web Site Design Method (WSDM)
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Phase: Mission Statement
Purpose
Subject
Target audience
eg. “To support the overall selection process (submission by authors,
evaluation, and selection by the Program Committee) of papers for
a conference.”
from: “The Conference Review System with WSDM”, Troyer, Olga De and Casteleyn, Sven (2001)
Web Site Design Method (WSDM)
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Phases and steps:
Phase: Audience modelling
- All users have specific information wants and needs,
we need to know these and design for them
Step1: Audience classification
- We need at this point to identify activities within the
website and the relationship a given user type has
with these
- Identify users and classify them into specific “user
classes” (e.g. lecturer, or student etc.).
- All user classes exist under a wider overall and
complete set of given users
Web Site Design Method (WSDM)
Step 2: Audience class characterisation
- Further user classes analysis
- Identify specific information requirements, the
“conceptual what” that the user class wants
- May diverge on actual information presentation,
e.g. salesman and car buyer have different
requirements for advertising information
- Analyze characteristics of user class, the
“conceptual who”, e.g. levels of experience,
frequency of use, motivation, & language etc.
Web Site Design Method (WSDM)
Phase: Conceptual design
Step 1: Task modeling
- We formally describe information requirements for
the different user classes
- Done via Object Role Model (ORM), Entity
Relationship Model (ERM), etc. – gives a view of
information required in the system
Customer
Has
For a
Account
Web Site Design Method (WSDM)
Step 1: Task modeling (cont.)
► Also need to think about the functionality
► Expand on functional requirements set out in Audience
Class Characterisation and model it using, for instance
Hierarchical Task Analysis (HTA) or perhaps an Entity
Life History (ELH) diagram
ENTITY X
A
E
B
F
C
G
D
H
*
Web Site Design Method (WSDM)
Step 2: Navigational design
► Construct a conceptual navigation model
► It consists of a number of navigation tracks – one for
each audience class
► Association of information chunks – Information as
components
► Association of functional chunks – Functions as
components
Conceptual Structural Model (3)

Conditional links may be needed
Visitor Track
C1
Registered
User Track
Un-Registered
User Track
Pre-Registered
User Track
Fully Registered
User Track
C2
C3
C4
C1: visitor is not fullRegistered
C2: visitor is fullRegistered
C3: visitor is PC-Chair
C4: visitor is Reviewer or p in PC-Member
C5: visitor is PC-Member
C6: visitor is PC-Author
PC-chair
Track
Reviewer
Track
C5
PC-Member
Track
C6
Author Track
© Prof. Dr. Olga De Troyer 2002
Web Site Design Method (WSDM)
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Phase: Implementation design
Page design
Presentation design
Data design
Phase: Implementation
Produces the end product of a web-site
WSDM: Conceptual Design
Mission statement:
• purpose
• target audience
• subject
Mission statement
Specification
Audience Class
Hierarchy
Audience Modeling
Audience
Classification
Audience Class
Description
• Requirements:
Information
Functional
Usability
• Characteristics
Audience Class
Characterization
Conceptual Design
Task Modeling
Navigational
Design
Author
Implementation design
Page
Design
Presentation
Design
Visitor
Data
Design
PC-Chair
Object Chunk C1
Reviewe
Track
(Name)
Subject
(Name)
*tr -> ?
{*s} -> ??
of
/for
PC-Member
Date
(dd/mm/yyyy)
*f -> ?
File
(URL)
Implementation
Paper
*p
/on
has
has
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Abstract
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UpdateSubmission
© Prof. Dr. Olga De Troyer 2002
/of last modification
*d -> TODAY
Paper Title
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in *p Paper
Storyboards
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•
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•
Simple paper based technique
Basically pictures and text to roughly illustrate the
make up / appearance of a screen
Not intended to be totally accurate,
Limited on interaction, but
shows screen sequences
Each screen is accompanied
by text to describe the scene,
user interaction and any
dynamic media (e.g. sound)
shown on a timeline
Conclusion
Methods
► General
problems to overcome…
 Favourite methodology
 Used to justify a pre-defined solution
►Power
of the analyst vs power of the
person/organisation purchasing the system
 Methodologies attempt to formalise messy
human based systems
Methods
► Why
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use one? – some reasons…
Documentation – transparency, communication
Standardisation – of approach, across groups
Modelling – tools, techniques for representation
Evaluation – validation, verification
Assignment?
On-Line Bank
► WISDM
 Mission Statement
 Audience Classes
 Audience Characterisation
For the tutorial…
► Think
about…(in WSDM terms)
 Task Modelling
►Information
requirements of your audience
►Functional requirements of your audience
 Navigation Design (for each audience class)
► Read:
http://wsdm.vub.ac.be/Download/Papers/WISDOM/WSDM
Paper.PDF
► Familiarise/re-familiarise
and ELH’s/HTA’s
yourself with ERM’s