Lecture IS3318
12/3/12
The Database Approach to Data Management
Microsoft Access Data Dictionary Features
Figure 6-6
Microsoft Access has a
rudimentary data dictionary
capability that displays
information about the size,
format, and other
characteristics of each field
in a database. Displayed
here is the information
maintained in the SUPPLIER
table. The small key icon to
the left of Supplier_Number
indicates that it is a key field.
Some Drawbacks…
• Complexity
• A DBMS is a complex piece of software all users must fully
understand it to make use of its functionalities
• Cost of DBMS
• The cost varies significantly depending on the environment and
the functionality provided. Must take into consideration recurrent
annual maintenance costs
3
Continued..
• Cost of Conversion
• Cost of converting existing applications to run on the
new DBMS and hardware. (additional training costs)
• Performance
• DBMS is written for applications in general which
means that some applications may run slower than
before
• Higher Impact of Failure
• Centralization of resources increases vulnerability of
the system
4
Database Administrator
•
•
•
•
•
Oversees a staff of database specialists
Final recommendations for DB design
Load and maintain DB
Establish security controls
Perform backup and recovery
5
Data Administration
Database
technology
And
management
Data
Administrator
Database
Management
System
Data planning
and modelling
technology
Users
6
Systems Analyst
• Or business analyst is a systems analyst that specializes
in business problem analysis and technologyindependent requirements analysis.
• A programmer/analyst (or analyst/programmer)
includes the responsibilities of both the computer
programmer and the systems analyst.
• Other synonyms for systems analyst include:
• Systems consultant
• Systems architect
• Systems engineer
• Information engineer
• Systems integrator
7
Role of the Systems Analyst
• Study problems and needs of an organization
• Determine best approach to improving
organization through use of:
• People
• Methods
• Information technology
• Help system users and managers define their
requirements for new or enhanced systems
8
Skills of a Successful Systems
Analyst
• Analytical
• Understanding of organizations.
• Problem solving skills
• System thinking
• Ability to see organizations and information systems as systems
• Technical
• Understanding of potential and limitations of technology.
9
Skills of a Successful Systems
Analyst
• Managerial
• Ability to manage projects, resources, risk and change
• Interpersonal
• Effective written and oral communication skills
10
System Owners
System owners are the information system’s sponsors and chief
advocates. They are usually responsible for funding the project to
develop, operate, and maintain the information system.
11
System Users
System users are the people who use or are affected by the
information system on a regular basis—capturing,
validating, entering, responding to, storing, and exchanging
data and information. A common synonym is client.
Types include:
• Internal users
• Clerical and service workers
• Technical and professional staff
• Supervisors, middle managers, and executive
managers
• Remote and mobile users (internal but disconnected)
• External users
12
Stakeholders: Players in the
Systems Game
• A stakeholder is any person who has an interest in an existing
or new information system. Stakeholders can be technical or
nontechnical workers.
• For information systems, the stakeholders can be classified as:
• System owners
• System users
• Systems analysts
• System designers
• System builders
• IT vendors and consultants
13
Systems Development Lifecycle
(SDLC)
• The systems development life cycle (SDLC) model
is an approach to developing an information
system or software product that is characterised
by a linear sequence of steps that progress from
start to finish without revisiting any previous
step.
• The SDLC model is one of the oldest systems
development models and is still probably the
most commonly used.
14
SDLC
• Traditional systems development lifecycle
(Waterfall Model)
• SDLC - very similar to a product life cycle in
the consumer market because both a new
product and information system develop
through a number of stages.
15
• The typical SDLC has the following steps:
• Initiation
• Feasibility study
• System Investigation
• System Analysis
• Systems Design
• Implementation
• Review and Maintenance
• These stages are frequently referred to as “conventional
systems analysis”, “traditional systems analysis”, “the
systems development life-cycle” or the Waterfall Model
16
SDLC or The Waterfall Model
• The waterfall model describes a development
method that is linear and sequential.
• Once a phase of development is completed, the
development proceeds to the next phase and
there is no turning back.
• The advantage of waterfall development is that it
allows for departmentalisation and managerial
control.
17
The Waterfall Model
Continued..
• A schedule can be set with deadlines for each
stage of development and a product can proceed
through the development process and
theoretically, be delivered on time.
• Development moves from concept, through
design, implementation, testing, installation,
troubleshooting, and ends up at operation and
maintenance.
18
Initiation
Traditional SDLC
Investigation
Analysis
Design
Implementation
NO FEEDBACK!!!!
Maintenance
19
SDLC
• This is now regarded as the “hard” systems approach
because of its rigid demarcation between phases.
• It has shortfalls which lead to a number of difficulties
• One major criticism of the model is that it doesn’t cater for
revisiting previous phases to correct defects.
• Feedback Loop – refinement of Waterfall Model
20
Potential Strengths of the Traditional SDLC
• It has been well tried and tested
• Use of documentation standards
• Following the methodology should aid (At least to some extent)
that roll out dates, budgets and expected benefits are met.
• At the end of each phase, all parties involved in the project can
review progress.
• Much greater control on the development of computer
applications and make possible the use of project management
tools and techniques
21
Potential Weaknesses of the Traditional
SDLC
• Criticisms of the methodology or perhaps of the
way it was used include:
•
•
•
•
•
•
•
Failure to meet the needs of management
Unambitious systems design
Instability
Inflexibility
User dissatisfaction
Problems with documentation
Lack of control
22
Potential Weaknesses of the Traditional
SDLC
•
•
•
•
•
Incomplete systems
Application backlog
Maintenance workload
Problems with the “ideal” approach
It does not allow for much reflection or revision.
23
Prototyping
• Building an experimental system rapidly and inexpensively for
end users to evaluate
• It will be refined until it conforms to the users’ requirements
• This is achieved through iterative development
24
Advantages of Prototyping
• Useful when there is uncertainty about system requirements
or systems design
• Valuable for End-user interface design
• Encourages end-user involvement throughout the systems
development lifecycle
25
Disadvantages of Prototyping
• Better suited for smaller application development.
• Prototyping may mean glossing over essential steps in the
system development.
26
Application Software Packages
• A set of prewritten, precoded application software programs
that are commercially available for sale or lease
• Packages have increased as many applications are common to
many businesses: payroll, accounts and inventory control
27
Advantages of Software Packages
• Most of the design work has been completed in advance
• Little extensive testing required
• Vendor support and maintenance
28
Disadvantages of Software Packages
• Disadvantages may be increased with a complex system
• Required customisation and additional programming may be
expensive
• Hidden implementation costs
29
End User Development
• The development of information systems by end
users with little or no formal assistance from
technical specialist
• It has been made possible by fourth generation
software tools (4GL)
30
Encouraging End User Development
• The variety of application development tools
available make it easier for end user development
• Guidelines for managers to encourage intranet
website development by end users:
•
•
•
•
•
Look for what makes sense
Spur creativity
Set some limits
Give managers responsibility
Make users comfortable
31
Advantages to End User Development
• Improved requirements determination
• Increased user involvement and satisfaction
• Reduced application backlog
32
Risks of End User Development
• It occurs outside the traditional mechanisms for
information system management and control
• Problems in ensuring that end-user developed
applications meet organisations objectives and
standards
• Rapid systems development without a formal
methodology may mean that testing and
documentation is inadequate
• Loose control of organisational data
33
Definition - Outsourcing
• The practice of contracting computer centre operations,
telecommunications networks, or application development to
external vendors
• Example: Bank of Ireland, Dell
34
Outsourcing
• Outsourcing has become increasingly popular as
companies believe that it is more cost effective than
maintaining their own IS staff
• Many companies are outsourcing software
procurement and support to application service
providers (ASPs) who provide and support business
application and other software via the Internet and
intranets to all of a company’s employees
workstations
35
Benefits of Outsourcing
• To reduce work in the information systems
department.
• When the IS function within an organisation is
limited.
• To improve the contribution of IT to enhance
business performance.
• To create new sources of revenue.
36
Benefits of Outsourcing
• To reduce work in the information systems
department
• When the IS function within an organisation is
limited
• To improve the contribution of IT to enhance
business performance
• To create new sources of revenue
37
Risks associated with Outsourcing
• May loose control over IS function
• Heavy reliance on the vendor
• Proprietary information may be leaked to the competition if
sensitive data is available outside the organisation
38
Sample Questions
• Discuss Porter’s Competitive Forces Model, considering the
role of information systems in gaining competitive advantage.
Illustrate your answer with diagrams and examples.
• Outline and briefly explain the stages involved on the Systems
Development Lifecycle (SDLC).