SYSTEMS
DEVELOPMENT LIFE CYCLE (SDLC)
n DEFINITION
PHASE:
n Feasibility
analysis
n Requirement
definition
n CONSTRUCTION
PHASE:
n System
design
n System
building
n System
testing
n IMPLEMENTATION
PHASE:
n Installation
n Operations
DEFINITION PHASE
n FEASIBILITY
ANALYSIS: Thorough analysis by team (leader, systems analysts, end-users).
Economic, operational, technical
n REQUIREMENTS
DEFINITION: If feasibility report approved, team develops logical design:
processes, data flow & relationships. Result is system requirements
document
CONSTRUCTION PHASE
n SYSTEM
DESIGN: Detailed design of physical system based on requirements document.
Details of hardware, software, databases, modules, interrelationships for
quality system (accurate, reliable, auditable, robust, changeable, secure,
efficient, user friendly, flexible, well documented)
n SYSTEM
BUILDING: IS specialists produce programs, databases. End-users answer
questions, interpret requirements, help design documents
n SYSTEM
TESTING: By module, subsystem, entire system to find & correct problems.
Users acceptance test
n DOCUMENTATION
IMPLEMENTATION
PHASE
n INSTALLATION:
Four strategies
n Parallel:
Run old & new systems for awhile to check validity. Safe
n Pilot:
Install in one part of organization at a time. Learn and adapt
n Phased:
In large system change one function at a time (e.g., order entry)
n Cutover:
Start using entire system. Can be dangerous if errors exist
n OPERATIONS:
Training, documentation, people and computers must work well together. Project
team disbanded
n MAINTENANCE:
Operations stage of life cycle. Correct errors as discovered, update as needed,
monitor activities and output. Be aware of gap between organization’s needs and
system’s performance
SDLC ROLES
n PROJECT
MANAGER: Must have IS skills, plans project, uses project management
tools, builds project team
n SYSTEMS
ANALYST: IS professional changes business problem into IS
solution
n END-USER:
Functional representative provides needs, judges results
n SPONSORS,
CHAMPIONS: Will be addressed in Chapter 12
*SDLC CHARACTERISTICS
n MANAGEABLE
PROJECT SIZE: Break into independent pieces. Stay within budget & other
constraints
n ACCURATE
REQUIREMENTS DEFINITION: Extraneous specifications lead to added expense,
extends completion
n EXECUTIVE
SPONSORSHIP: Sponsor with responsibility and resources critical to success
*SDLC ADVANTAGES
n HIGHLY
STRUCTURED, SYSTEMATIC PROCESS
n THOROUGH
DEFINITION REQUIREMENTS
n CLEAR
MILESTONES WITH MANAGEMENT SIGN-OFFS
n MAY
IGNORE EVOLVING REQUIREMENTS DURING PROJECT
n TIME-CONSUMING,
COSTLY PROCESS
n TOP-DOWN
COMMITMENT REQUIRED
n SDLC
DISADVANTAGES
n MAY
IGNORE EVOLVING REQUIREMENTS DURING PROJECT
n TIME-CONSUMING,
COSTLY PROCESS
n TOP-DOWN
COMMITMENT REQUIRED
*
PROTOTYPING
LIFE CYCLE
1. IDENTIFY
REQUIREMENTS
2. DEVELOP
INITIAL PROTOTYPE
3. USE
PROTOTYPE, NOTE CHANGES
4. REVISE,
ENHANCE PROTOTYPE: Return to Step 3 as needed
5. EVALUATE
OPERATIONAL SYSTEM
6. MAKE
CHANGES OR ABANDON
7. INSTALL,
OPERATE, MAINTAIN
*
COMBINING
PROTOTYPING & SDLC
n PROTOTYPING/PILOTING
PHASE:
n DETERMINE
BASIC REQUIREMENTS
n PROTOTYPE
SYSTEM
n PILOT
PROTOTYPE
n SDLC
CONSTRUCTION PHASE:
n SYSTEM
BUILDING
n SYSTEM
TESTING
n SDLC
IMPLEMENTATION PHASE:
n INSTALLATION
n OPERATIONS
n MAINTENANCE
*
JOINT
APPLICATION DESIGN (JAD)
n TECHNIQUE
INVOLVING TEAM OF USERS, IS SPECIALISTS
n INTENSE,
STRUCTURED PROCESS
n DEVELOP
REQUIREMENTS OR REVIEW DESIGN PROPOSAL
n CAN
LAST HOURS, DAYS, OFTEN AT LOCATION REMOVED FROM WORKPLACE
*
COMPUTER-AIDED
SOFTWARE ENGINEERING (CASE)
COLLECTION OF SOFTWARE TOOLS TO AUTOMATE SDLC PROCESSES:
n DIAGRAMMING
TOOLS
n COMPUTER
DISPLAY, REPORT GENERATORS
n ANALYSIS
TOOLS
n CENTRAL
REPOSITORY
n DOCUMENTATION
GENERATORS
n CODE
GENERATORS
*
RAPID
APPLICATION DEVELOPMENT (RAD)
n HYBRID
OF SDLC, PROTOTYPING, JAD, CASE
n PRODUCE
SYSTEM IN 6 MONTHS OR LESS
n STEPS:
n PLANNING
n USER
DESIGN
n CONSTRUCTION
n IMPLEMENTATION
(CUTOVER)
*
RAD
ADVANTAGES
n DRAMATIC
SAVING IN TIME
n FOCUSES
ON ESSENTIAL SYSTEM REQUIREMENTS
n ABILITY
RAPIDLY TO CHANGE SYSTEM DESIGN AT USER’S REQUEST
n QUALITY
MAY BE SACRIFICED FOR SPEED
n TIME
CONSUMING FOR KEY PERSONNEL
n POSSIBLE
SHORTCUTS ON INTERNAL STANDARDS, MODULE REUSABILITY
*
OBJECT-ORIENTED
METHODS (O-O)
n HOLD
GREAT PROMISE TO PRODUCE BETTER SYSTEMS AT LESS COST
n OBJECTS
HIGHLY COHESIVE, LOOSELY COUPLED, REUSABLE
n CAN
REDUCE ERRORS, IMPROVE MAINTENANCE
*
QUIS ANSWERED PAS PERTEMUAN TERAHIR
1.
The existing system is evaluated.
Deficiencies are identified. This can be done by interviewing users of the
system and consulting with support personnel.
2.
The new system requirements are
defined. In particular, the deficiencies in the existing system must be
addressed with specific proposals for improvement.
3.
The proposed system is designed. Plans
are laid out concerning the physical construction, hardware, operating systems,
programming, communications, and security issues.
4.
The new system is developed. The new
components and programs must be obtained and installed. Users of the system
must be trained in its use, and all aspects of performance must be tested. If
necessary, adjustments must be made at this stage.
5.
The system is put into use. This can
be done in various ways. The new system can phased in, according to application
or location, and the old system gradually replaced. In some cases, it may be
more cost-effective to shut down the old system and implement the new system
all at once.
6.
Once the new system is up and running
for a while, it should be exhaustively evaluated. Maintenance must be kept up
rigorously at all times. Users of the system should be kept up-to-date
concerning the latest modifications and procedures.
The technical activities fall into a
number of major categories:
- System Definition (Analysis, Design, Coding)
- Testing
- System Installation (e.g., Data Conversion, Training)
- Production Support (e.g., Problem Management)
- Evaluating Alternatives
- Defining Releases
- Reconciling Information Across
Multiple Phases
- Reconciling To A Global View
- Defining The Project's Technical
Strategy)
Definition: One-to-many relationships
occur when each record in TableA may have many linked records in TableB but
each record in TableB may have only one corresponding record in TableA
a many-to-many relationship
is a type of cardinality that
refers to the relationship between two entities (see
also Entity-Relationship Model) A and B in which A may contain a parent row for
which there are many children in B and vice versa. For instance, think of A as
Authors, and B as Books. An Author can write several Books, and a Book can be
written by several Authors. Because most database management
systems only support one-to-many relationships,
it is necessary to implement such relationships physically via a third junction
table (cross-reference table),
say, AB with two one-to-many relationships
A -> AB and B -> AB. In this case the logical primary
key for AB is formed from the two foreign
keys (i.e. copies of the primary
keys of A and B).
type of e-commers transaction
Consumer-to-Consumer(C2C).:E-commerce in
which an individual sells products or services to other individuals.
Customer -to-Business (C2B).:E-commerce
in which customers make known a particular need for a product or service, and
suppliers complete to provide the product or service to consumers .
Intrabusiness( intraorganizational)
commerce. E-commerce in which an organization uses EC internally to improve its
operations.
n Electronic
Payments
Electronic Checks
Electronic Credit Cards
Purchasing Cards
Electronic Cash
Electronic Bill Presentment and Payments
Paying Bills at ATMs.
n Three forms of electronic
cash
Person- to-Person Payment. A form of
e-cash that enables the transfer of funds between two individuals, or
between an individual and a business,
without the use of a credit card.
Stored-value money card. A form of
e-cash on which a fixed amount of prepaid money is stored, the amount is
reduced each time the card is used.
Smart card. A form of e-cards, that
contains a microprocessor (chip) that enables the card to store a considerable
amount of information and to conduct processing .
n Security
in Electronic Payment
Authentication. The buyer, the seller,
and the paying institution must be assured of the identity of the parties with
whom they are dealing.
integrity. It is necessary to ensure
that data and information transmitted in EC, are not accidentally or
maliciously altered or destroyed during transmission.
Nonrepudiation. Merchants need
protection against the customer’s unjustified denial of placing an order. On
the other hand , customers need protection against merchant’s unjustified
denial of payment made. (such denials, of both types, are called repudiation)
Privacy. Many customers want their
identify to be secured.
Safety. Customers want to be sure that
it is safe to provide a credit card number on the Internet.
n Security
Protection
E-wallets (digital wallets). Mechanisms
that combine security measure and convenience in EC purchasing.
Virtual credit card. A payment mechanism
that allows a buyer to shop with an ID number and a password instead of with a
credit card number. 
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