Chapter 2
The database
development process
Information Systems
Architecture
A conceptual blueprint
or plan that expresses the
desired future structure
for the information
systems in an
organization.
Architecture example
Business
Operations
Customers
& Suppliers
External
Events
Integrated
data warehouse
CIM
EDI
External
database
access
Data
validation
and
retention
Access
analysis and
presentation
tools
Information
delivery system
Dialogue
Decision makers
Customers, Suppliers
A more sophisticated example...
Information Systems Architecture
 Key
•
•
•
•
•
•
components:
data
processes which manipulate data
network which transports data
people who perform processes and send and
receive data
events and points in time when processes are
performed
reasons for events and rules which govern data
processing
Information Engineering
An Information Systems
Architecture is developed
by IS planners following
a particular methodology
such as Information
Engineering.
Information Engineering
 Data-oriented
methodology
 Uses
top-down planning in which specific
information systems are deduced from a broad
understanding of organization’s information
needs, rather than relying on specific user
information requests
 Offers
perspective on relationship of information
systems to business objectives
Top-Down vs. Bottom-Up
Top-Down Planning:
Bottom-Up Planning:
A methodology that
attempts to gain a
broad understanding
of the information
system needs of the
entire organization
A methodology that
identifies and defines IS
development projects based
upon solving operational
business problems or taking
advantage of business
opportunities
The big picture...
Information engineering
Information systems planning
– Identify strategic planning factors (goals,
CSFs, problem areas)
• IT vision
– Identify corporate planning objectives
• Information system architecture
– Develop enterprise model
Systems analysis
Systems design
implementation
Systems Development Life Cycle
Project Identification & Selection
Project Initiation & Planning
Analysis
Logical Design
Physical Design
Implementation
Maintenance
Database SDLC
SDLC
Identify Project
Initiate and Plan
Analyze
Logical Design
Physical Design
Implementation
Maintenance
Database Development
Activities
Enterprise
Modeling
Conceptual
Data Modeling
Logical
DB Design
Physical DB
Design/Creation
DB
Implementation
DB
Maintenance
Planning Matrixes
Show
interrelationships between
objects. Among the possibilities:
• Location-to-Function
• Unit-to-Function
• Information System-to-Data Entity
• Supporting Function-to-Data Entity
• Information System-to-Objective
Business Function-to-Data Entity Planning
Matrix
Information System-to-Objective Planning
Matrix
Functional Decomposition
Enterprise Data Modeling
The first step in
database development,
in which the scope and
general contents of
organizational databases
are specified.
Enterprise Data Model
 A model
which includes:
• overall range of organizational databases
• general contents of organizational databases
 Built
as part of IS planning for the
organization and not the design of a
particular database
part of an organization’s overall
information systems architecture (ISA)
 One
Conceptual Database Modeling
 Determine
 Determine
 Build
user requirements
business rules
conceptual data model
• outcome is an entity-relationship
diagram or similar
communication
tool
• population of repository
Enterprise
Modeling
Conceptual
Data Modeling
Logical
DB Design
Physical DB
Design/Creation
DB
Implementation
DB
Maintenance
Logical Database Design
 Select
logical database model
• commit to a database alternative
 Map
Entity-Relationship Diagrams
 Normalize
 Specify
data structures
business rules
Enterprise
Modeling
Conceptual
Data Modeling
Logical
DB Design
Physical DB
Design/Creation
DB
Implementation
DB
Maintenance
Physical Database Design
 Select
DBMS
 Select
storage devices
 Determine
 Design
files and indexes
 Determine
 Specify
access methods
database distribution
update strategies
Enterprise
Modeling
Conceptual
Data Modeling
Logical
DB Design
Physical DB
Design/Creation
DB
Implementation
DB
Maintenance
Database implementation
 Code
and test database processing
programs
 Complete
 Install
documentation
database and convert data
Enterprise
Modeling
Conceptual
Data Modeling
Logical
DB Design
Physical DB
Design/Creation
DB
Implementation
DB
Maintenance
Database Maintenance
 Analyze
database and applications to
ensure evolving information
requirements are being met
 Tune
database for improved
performance
 Fix
errors
 Provide
data recovery when needed
Enterprise
Modeling
Conceptual
Data Modeling
Logical
DB Design
Physical DB
Design/Creation
DB
Implementation
DB
Maintenance
Documentation

most formal development methodologies are
documentation based

helps managers monitor progress and quality of
project
 facilitates
communication between team members

includes models

various stages are not complete until
documentation is accepted
Some Keys to Success...
accurate
requirements definition
commitment
effective
change management
manageable
champion
size
So …
Three Schema Architecture for
Database Development
 Conceptual
Schema
• Analysis project phase
 External
Schema
• Analysis and Logical Design phases
• (subset of conceptual schema)
 Internal
Schema
• Physical Design phase
3-schema architecture
Conceptual Schema
Describes
the logical structure of the
entire database
Independent
Avoids
Stated
of a specific DBMS
details of physical design
in
• ERDs
• metadata
External Schema
Also
called a user view
Specifications
include screen
formats, report formats, transaction
definitions
Physical Schema
 Describes
physical structure of entire
database
 Specifies
how data from a conceptual
schema are stored in secondary memory
 Sometimes
called internal schema
 Specifications
include physical file and
data structures, storage organization, and
index structures
3-schema development process
Rapid application development
 design
methodology which speeds systems
delivery through a combination of speedy
design iterations, data modeling,
user/developer teamwork, and automated
development tools.
 encompasses
a set of techniques that can be
used to build complex, strategic, and
mission-critical applications in months
rather than years
RAD
The RAD lifecycle
 requirements
planning
• conduct joint requirement planning workshop
 design
• conduct JAD workshop
 construction
• members of team monitor evolution, system is
prototyped
 cutover
• installation
Within the time box...
Requirements
planning
User design
construction phase
build and evolve
prototype
User review
request for change
Evaluate
system
cutover
time box
Barriers to overcome...
 poor
training/ tools
 reluctance
to leave old methods behind
 mindset
that RAD is not adequate for largescale systems development
 speedy
delivery does not mean low quality
 “creeping
functionality”