Transcript Information Systems 1

IMS3230 - Information Systems
Development Practices
Blended approaches:
Information Engineering
4.1
Information Engineering
 Martin and Finkelstein (1981), Martin (1989), several
versions
 data oriented methodology
 full lifecycle coverage
 organisation-wide perspective on planning of information
technology and information systems
 top-down analysis and development of organisation’s
applications
 focus on data and activities
 well-supported by CASE tools e.g. IEW, IEF
 has evolved
 widely used
4.2
Information Engineering
evolution
 data base technology
 data analysis and data management
 strategic data models, procedure formation
 4GLs and “productivity tools”, e.g. code generators
 alignment of information systems planning with strategic
business planning
 process modelling techniques
 CASE technology, “encyclopedia”, knowledge
coordinator
 RAD (Rapid Application Development)
 object-oriented concepts
4.3
Information Engineering
 data centred:
model data requirements first, processes later
(data is more stable)
applications will be integrated by a common data
framework
 information engineering:
“an interlocking set of formal techniques in which
enterprise models, data models and process models are
built... and are used to create and maintain data
processing systems”
James Martin (1986)
 use of diagrams as a communication and representation
4.4
tool
Major phases of Information
Engineering
 information strategy planning
to build an information and technology architecture to
support business strategy and objectives
 business area analysis
to identify data and function requirements of each
business area
 individual systems planning
 systems design
to complete logical specifications for a system and
convert these into physical design specifications
 construction
to generate code, test, and install the system
 cutover
4.5
Phase 1 - information strategy
planning:
 corporate management and planners assess the
organisation:
business mission, objectives, CSFs, performance
measurements, organisation structure, current situation
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construct corporate data model
determine major business functions
identify business areas, including goals and CSFs
determine:
information architecture (global entities and business areas)
information systems architecture (business sytems)
technical architecture (technology: hw/sw/comms)
information strategy plan (priorities)
4.6
Phase 2 - business area analysis:
 identify and model in detail the fundamental data and
activities required to support a business area
 ensure that requirements are independent of technology
 ensure that requirements are independent of current
systems and procedures
 ensure that requirements enable business area’s goals
and CSFs to be supported
 ensure that requirements are independent of the current
organisational structure
 a high-level executive sponsor is necessary
4.7
Business area analysis: steps
 extract the relevant entity relationship model and businessfunction decomposition models
 identify relevant departments, locations, business goals, CSFs
 create a preliminary data model: identify events, entity life
cycles, initial attributes
 create a preliminary process model: decompose the functions
into processes
 model data and processes of existing systems for comparison
 involve all affected end-users in iteratively building:
a detailed data model, a detailed process model, entity /
process matrices
4.8
 identify and prioritise system development projects
Business area analysis:
techniques
 data model
entity relationship modelling
attribute collection
normalisation
canonical synthesis
 process model
process decomposition models
process dependency diagrams
 data and activity interaction
entity lifecycles
process / entity matrix
4.9
Information engineering:
phases 3 and 4
 Phase 3 - individual systems planning
use JRP for individual systems planning
 Phase 4 - system design:
concerned with how selected processes in the business
are implemented in procedures and how these
procedures work
use the logical data and process models to design the
external representations of the system
direct end-user involvement is essential
identify reusable procedures
use prototyping
use JAD
4.10
System design techniques
 prototyping
 detailed process models: procedure design using
access path and volumes analysis, dialogue flows
and menu structures,
 physical database design, file design,
 screen displays
 menu flows
 report layouts
 on-line procedures and software
 batch procedures and software
 design verification and testing
4.11
Information engineering:
phases 5 and 6
 Phase 5 - construction:
technical design, create physical databases
create modules and programs, unit testing
system testing, documentation
 Phase 6 - cutover:
conversion
final testing
conduct training
install the system, review implementation
4.12
Information Engineering
features:
 organisation-wide perspective aligned with strategic
business planning
 comprehensive
 emphasis on user involvement e.g. JAD, JRP
 evolves by incorporating new techniques, concepts,
technologies e.g. RAD, object-oriented concepts
 evolves from practice e.g. shortened ISP phase
 emphasis on automation e.g. 4GLs, I-CASE, prototypes
 primarily for database transaction processing systems
 little event or behaviour modelling
4.13
Information Engineering
features:
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after ISP phase, activities can proceed in parallel

high level data and process model (co-ordinating
model) enables this by highlighting interfaces and
dependencies between systems etc.
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flexible paths through the methodology
e.g. reverse engineering and re-engineering
4.14
References
 Prescribed text:
Avison, D.E. & Fitzgerald, G. (2003).
Information Systems Development:
Methodologies, Techniques and Tools. (3rd ed),
McGraw-Hill, London.
Chapter 20.3
Refer to additional references in the readings at the unit web page and in the
prescribed text
4.15