Transcript COM332 – SA3 - Glyndŵr University

COM332 – SA3
WISDM & SSM
• Web development approaches
– Focused on the user interface and in particular the
look and feel of a web site
– Failed to address the wider aspect of web-based
information systems.
• Traditional IS development methodologies
– Have struggled to accommodate web specific
aspects into their methods and work practice.
• Web based information system requires a
mixture of web site development techniques
together with traditional IS development
competencies in database and program
design.
• WISDM is based on Multiview frame work
• Multiview is framework that provides the basis
for constructing a situation–specific
methodology.
• The WISDM matrix
– The IS development matrix categorise the
methods in two dimension
• Socio (organisation and people) and technical (the
things)
• On one hand analysis (what is required) and on the other
design (how it will be achieved).
ANALYSIS
(what)
Information analysis –
Requirements
specification
Organisational
analysis –
value creation
S
O
C
I
O
(people and
organisations)
Work design
–
User
satisfaction
Technical
design –
Software
model
T
E
C
H
N
I
C
A
L
(things)
HCI –
user
interface
DESIGN
(how)
• Hard (engineering) based approaches to IS
development concentrate on right hand side
of the matrix
– The generation of requirements specification and
its stepwise refinement into a software model.
• Multiview approach is more even handed
– Seek a socio technical solution giving a balance to
the left and right hand side of the matrix
• The matrix does not require activities to be
carried out in any particular sequence or
hierarchy
• Vidgen et al. (2002) offer the metaphor of a
film camera
– “The focus of attention changes as the camera
zooms in and then out …; moves from one aspect
to another; revisits an aspect and finds that the
situation has changed. One aspect might be the
focus of attention …, but the other aspects are in
peripheral vision and can still make their presence
felt … It is possible to see all five aspects at the
same time, but only by sacrificing the level of
resolution. By contrast, it is possible to focus in
and examine one particular aspect in great detail,
but at the expense of losing some of the context”
• ORGANISATIONAL ANALYSIS
• Represents value creation.
– Compare the place of strategy in the
traditional systems development life cycle.
– Does strategy play a more important rôle in
web-based systems?
– What is the strategic horizon?
• INFORMATION ANALYSIS
• Represents requirements specification.
– Data and process requirements need to be
modelled
• Any form of model may be used
– A verbal descriptive model
– A graphical (diagrammatic) model such as SSADM’s entity
relationship diagrams and dataflow diagrams
– The WISDM indicative approach is to use UML (Unified
Modelling Language) – this implies that an object-oriented
approach is followed
» Strictly speaking, we should not talk of data and
process being modelled separately, since the OO
philosophy is that they should not be separated.
• TECHNICAL DESIGN
• Represents the software model.
– Effectively, this will be the database design.
• For a relational database, this may well be
derived from an entity-relationship diagram
– Need to be read in conjunction with the UML class
diagrams produced as part of the Information
analysis.
• An ER diagram can be seen as a design
derived from a UML analysis
• HCI
– Represents the user interface.
– Part of technical and work design
• WORK DESIGN
– Represents user satisfaction.
– The WISDM indicative approach for users inside
the organisation is to use Enid Mumford’s ETHICS
(Mumford, 1995) method or one of the family of
methods known as the Scandinavian approach.
– Web-based systems are characterised by users
who are outside the organisation (particularly
customers),
• Additional approach such as Webqual (Barnes & Vidgen,
2002) is recommended in this case.
SOFT SYSTEMS METHODOLOGY
• Hard approach: characterised by
– Engineered
– Systematic
• reduce to parts
– Structured
– Clear boundary
– Clear objectives
• Solve the problem
• Soft approach: characterised by
– Systemic
• Holistic view
– ill-structured
– unclear (fuzzy) boundary
– unclear (fuzzy) objectives:
• structure the problem
• Hard approach:
– Concerned with artefacts
• Soft
– Concerned with systems (emergent
properties)
• Hard approach seeks:
– Technical solutions
• Soft approach seeks:
– Social, political, economical and technical solution
• Soft System Methodology
– An organised way of tackling the messy
situation in the real world
– Helps managers of all kinds and all levels
to cope with their tasks
– Based on system thinking
• Enables it to be highly defined and described
but is flexible in use and broad in scope.
• Peter Checkland (1984) systematised the soft
approach into SSM (Soft Systems
Methodology).
• The systems approach means that it’s
important to look at the whole context,
– Hard systems thinking assumes that a scientific
approach - to achieve a specific goal - will always
work,
– Soft thinking recognises that problems are never
clearly defined.
• The systems principle also implies that we
must try to develop applications systems for
the organisation as a whole rather than for
functions in isolation.
• SSM was developed through action
research,
– The investigator takes part in the process;
the focus was the search in each case for
a set of assumptions (Weltanschauung or
world-view).
• There are even stages in SSM.
– There are real world activities and system
thinking.
• The sequence is merely a logical sequence,
it is possible to start the project at any step.
1.
2.
3.
4.
5.
6.
7.
The problem situation unstructured
The problem situation expression
Root definitions of relevant system
Conceptual model
Comparing 4 & 2
Feasible, desirables changes
Action to improve the problem situation
• First two stages is concerned with
finding about the problem situation from
as many peoples in that situation as
possible.
• There will be many different views.
• Given the informal view of the problem situation
gathered in stage 1, stage 2 attempts to express the
problem situation in more formal way.
– Rich pictures is widely used for this purpose.
• A picture of the situation and environment in diagrammatic and
pictorial form
• It will show the people involved, problem areas, controlling
bodies and sources of conflict.
• Aid in discussion between the problem owner and problem
solver
• To help the problem solver better understand the problem
situation.
– From rich picture problem solver extracts problem themes,
things noticed in the picture that are, or may be, causing
problems
– Rich pictures intended to help in identifying problem, not for
recommending solutions
• Next, possible systems that would be useful
in this situation are identified from the rich
picture.
– Problem :– conflict between two departments
– Relevant system :– systems for reducing
department boundaries.
• Root definitions are produced for each
system using the CATWOE criteria (client,
actor, transformation, world-view, owner,
environment).
• Root definition is a concise tightly constructed
description of a human activity system which
states what the system is.
• Next, a conceptual model showing
subsystems and their interaction is
developed.
– Conceptual model is a diagram of activities
showing what the system, described in the root
definition, will do.
• Then the conceptual model is compared with
real life in order to arrive at a useful course of
action.
– Comparison of rich picture to conceptual model.
– The debate about possible changes should lead to
a set of recommendations regarding the change in
order to help the problem situation.
• Next stage concerns an analysis of proposed
changes from stage 5 to draw up proposals
for those changes which are considered both
feasible and desirable.
• Final stage is about recommending action to
help the problem situation.
– The methodology does not describe a method for
implementing the solution.
• SSM provides all actors including the
analysts the opportunity to understand
and to deal with the problem situation.
• The process is iterative and the analysts
learn about the system and are not
expected to follow a laid down set of
procedures.
• SSM mode 1 is still the version most
commonly referred and most useful in an
information system context.
• There is an alternative version SSM mode 2
proposed by Checkland and Scholes (1990).
• People using SSM mode 2 follow two strands
of enquiry.
– Logic-driven stream
• Models human activity system
– Cultural stream
• Examines three aspects of problem situation
– The intervention itself, the situation as a social system, and
the situation as a political system