Transcript COMPLETING SYSTEMS ANALYSIS CONSIDER ALTERNATIVE …

Phase 2 – Systems Analysis
Transition to Systems
Design
Chapter 6
Objective





Evaluate software alternatives and
development strategies.
Explain advantages and disadvantages of
developing in-house software versus
purchasing and customizing software.
Describe how companies use outsourcing
and user applications.
List the steps in purchasing and evaluating a
software package
Explain the differences between a request for
proposal (RFP) and a request for quotation
(RFQ).
Objective





Describe the system requirements document
and the presentation to management at the
end of the systems analysis phase.
Explain the transition from systems analysis
to systems design, and the difference
between logical and physical design.
Explain the importance of prototyping and
describe various prototyping methods, tools,
and techniques.
Discuss the system design process.
Create and use appropriate codes during
systems design and development.
SOFTWARE ALTERNATIVES
 DEVELOP
IN-HOUSE
 PURCHASE SOFTWARE
PACKAGES
IN HOUSE
Software developed by technical
staff in a company’s information
systems department
SOFTWARE PACKAGE
 Software
written by another
company and available for
purchase
 commercial application software
 available for sale by software
publishers or software vendors
HORIZONTAL SOFTWARE
 Software
package that can be
used by many different types of
organizations
–Accounting
–Invoicing
–Accounts payable
VERTICAL SOFTWARE
 Software
developed to handle
requirements of IS for specific type
of organization
– colleges
– banks
– insurance companies
– doctor offices
Developing Your Own Software
 Satisfy
unique requirements
 Minimize changes to business
procedures and policies
 meet constraints of existing system
 meet constraints of existing
technology
 utilize new technology
Buying a Software Package
 Less
expensive
 Less time to implement
 Fewer errors
 Already in use in other companies
 Requires fewer technical staff for
development
 Upgraded by vendor
–????????
Customize Software Packages
 Off
the shelf package
–vendor’s standard package
 Customized package
–a software package that YOU or
the VENDOR modify to meet
your unique specifications
Customizing Software Packages
 Vendor
makes modifications
–$$$$$ and time
 YOU make modifications
–time , money and technical
expertise
 Add on supplemental components
Application Service Providers
ASP
 Delivers applications, or access to
applications, by charging a usage or
subscription fee
 Application hosting

Outsourcing

Use of outside company to handle a portion
of company’s IT work load
 Either temporary or long-term
 Advantages??
 Disadvantages??
–consulting firms
–consultants
–contract programmers
User Applications

Typically use standard business
software (Office 2000), to allow user to
perform tasks
User Applications
 Development
of entire/portion of IS
by end users for a company
–limited to end user department
–not integral to central IS
–spreadsheets, database reports
–often 4th generation tools
User Applications
 WHY
–NOT ENOUGH TIME FOR IS
TO DO EVERYTHING
Selecting Software Steps
1.
2.
3.
4.
5.
Evaluate IS requirements
Identify potential software
vendors
Evaluate software package
alternatives
Make the purchase
Install the software package
Evaluate IS Requirements
 Identify
key features of IS
 Identify IS current volume and future
growth
 Specify IS external constraints
–hardware and software
 REQUEST FOR PROPOSAL -- RFP
Identify Potential Vendor
 PC,
midrange, mainframe,
network????
 Horizontal vs Vertical
–Computer store (PC only)
–Hardware manufacturers
–Industry trade magazines
 Relative cost for pc vs mainframe
EVALUATE SOFTWARE
PACKAGE ALTERNATIVES

Compare identified possible software
package solutions
– vendor presentations
– Existing users
– benchmarks
– literature
– evaluations in trade journals
– evaluations from market research
– try it yourself
EVALUATE SOFTWARE
ALTERNATIVES
 BENCHMARK
TEST
–measure time it takes to
process set number of
transactions
–compare different software
results
MAKE THE PURCHASE
 WHAT
DO YOU ACTUALLY
PURCHASE??
 SOFTWARE LICENSE
–right to use the software under
certain terms and conditions
–single computer restriction very
common
MAKE THE PURCHASE
 network??
-- site license
 leasing agreements
 MAINTENCE AGREEMENT
–give you the right to contact
vendor for assistance
INSTALL SOFTWARE
 IMPLEMENTATION
–Load software
–Test software
–Train end users
–Convert data to system files
HARDWARE ALTERNATIVES
 Request
for Quotation
 Request for Bid
TURNKEY SYSTEM
 Complete
IS that includes all
hardware, systems and application
software, documentation, training,
installation, and support from
outside vendor
 Usually used in smaller companies
COMPLETION OF SYSTEMS
ANALYSIS
 Systems
Requirement
Document
 Formal Presentation
SYSTEMS REQUIREMENTS
DOCUMENT








Management Summary
IS Background
Functional Requirements
Environmental Requirements
Alternatives
Recommended Alternatives
Time and Cost Estimates
Appendices
SYSTEMS REQUIREMENTS
DOCUMENT
Could
be lengthy!!!
Presentations after Systems
Analysis Phase
 One
of the most critical
milestones in entire SDLC
POSSIBLE MANAGEMENT
DECISIONS
 Develop
in-house
 Modify current system
 Purchase software package
 Purchase and develop in house
 Perform additional systems
analysis
 Stop all further work
CHANGE CONTROL
 Process
of managing and
controlling the requested
changes in requirements for an
information system
CHANGE CONTROL
 Freeze
the requirements
–maximize chance for
successful delivery of IS that
satisfies requirements within
projected costs and schedules
 Change is inevitable
Transition to Systems Design
 Analysis
Phase – logical or essential
model
– Logical design of IS defines the functions
and features of system and relationships
among its components
– Includes the output that must be produced,
the input needed, processes that must be
performed
– without regard to how tasks will be
accomplished physically
Transition to Systems Design
 Design Phase – physical model
– Physical design of IS is a plan for the actual
implementation of the system
– Built on logical design
–Describes the actual processes of
entering, verifying and storing data,
physical layout of data files, sorting
procedures, exact format of
reports…
PROTOTYPING
 Early,
rapidly developed
working version of IS that
exhibits the essential features
of the target IS
 working model
Approaches to Prototyping

System prototyping – full-featured,
working model of IS, ready for
implementation
– RAD

Design prototyping (throwaway)
– Used to verify user requirements, after
which the prototype is discarded
– Gives us a user approved design
PROTOTYPING TOOLS
 Procedural
tools
vs. non-procedural
Prototyping Tools
Data Dictionary
 RDBMS
 report generator
 query language
 screen generator
 application generator
 4 GL

Prototyping during Systems
Analysis
 given
to end users to evaluate how
well it satisfies their needs
 working model -- changes made often
 takes time to develop and evaluate
 lower costs in later phases of SDLC
CASE TOOLS
 SOFTWARE
PRODUCT THAT
AUTOMATES A SPECIFIC
SYSTEMS LIFE CYCLE TASK
–Screen generator
–Computerized data dictionary
–Advantages and
Disadvantages
CASE tools
of
ALTERNATIVE GRAPHICAL
TOOLS
 System
flowchart
SYSTEMS DESIGN
Look carefully at system
requirements from systems
analysis phase to complete
system design
 Components
of IS are
interdependent
 First must thoroughly
understand entire logical design
before beginning physical
design
First step of System Design
 Review
system requirements
document from Systems Analysis
phase
–analyst assigned to design may
not have participated in analysis
–time has passed since analysis
phase
SYSTEM DESIGN
ACTIVITIES
 Need
to consider IS
components of data, data
stores, people, procedures,
hardware, software, and
information
interrelationships
DESIGN TIPS FOR
SYSTEM DESIGN
End
user considerations
Data considerations
Processing considerations
Designing and using Codes
Code – a set of letters or numbers that
represent a data item
 Can be used to simplify output, input
and data formats
 Consider early in design phase
 Efficiency

Types of Codes
Sequence
 Block sequence
 Alphabetic

– Category
– Abbreviation

Significant digit
Types of Codes
Derivation
 Cipher
 Action
 Self-checking
