chap05
DESCRIPTION
tskkTRANSCRIPT
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PHASE 2SYSTEMS ANALYSIS
Evaluating Alternatives and Strategies
SYSTEMS ANALYSIS & DESIGN
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SYSTEMS ANALYSIS & DESIGN 3E
Chapter 5
Evaluating Alternatives and Strategies
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Chapter 5 covers the remaining tasks in the systems analysis phase Evaluation of alternative solutions Preparation of the system requirements
document Presentation to management
Introduction
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Evaluating Software Alternatives
Make or buy decision In-house software
Developed by the company’s IS department
Software package Purchased or leased from software
publishers or vendors Horizontal application Vertical application
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SYSTEMS ANALYSIS & DESIGN 3E
Evaluating Software Alternatives
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Evaluating Software Alternatives
Developing software in-house Reasons for in-house development
Satisfy unique requirements Minimize changes in business procedures
and policies Meet constraints of existing systems Meet constraints of existing technology Develop internal resources and capabilities
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Evaluating Software Alternatives
Buying a software package Reasons for buying a software package
Lower costs Requires less time to implement Proven reliability and performance
benchmarks Implemented by other companies Requires less technical development staff Future upgrades provided by the vendor
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Evaluating Software Alternatives
Customizing software packages Purchase a basic package that can be
customized to suit your needs Negotiate with software vendor to make
enhancements to suit your needs Purchase the package and make your own
modifications
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Evaluating Software Alternatives
Other software alternatives Outsourcing End-user systems Enterprise computing
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Evaluating Software Alternatives
Outsourcing Using outside companies to handle part
of the workload, on short-term or long-term basis
Contract personnel firms Systems management or facilities
management firms
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Evaluating Software Alternatives
End-user systems Major factor in systems planning and
development Applications can be managed by end-users Software suites offer integrated
applications Interactive Help features include wizards Security concerns might require read-only
files Information centers (IC) can support end-
user systems
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Evaluating Software Alternatives
Enterprise computing Overall information management strategy Key is effective integration of
information resources Many systems involve client/server
architecture
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Evaluating Software Alternatives
Selecting a software alternative Decision will affect remaining SDLC phases Systems analyst’s involvement depends on
which alternative is selected
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Evaluating Software Alternatives
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Steps in Evaluating and Purchasing Software Packages Five step process
1. Evaluate the information system requirements
2. Identify potential software vendors
3. Evaluate software package alternatives
4. Make the purchase
5. Install the software package
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Steps in Evaluating and Purchasing Software Packages
Step 1: evaluate the information system requirements
Identify the key features of the system Estimate volume and future growth Specify any hardware constraints Prepare a request for proposal or quotation
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Steps in Evaluating and Purchasing Software Packages
Step 2: identify potential software vendors Next step is to contact potential vendors An RFP will help vendors to identify
solutions Various sources of information on suppliers
Retailers Computer manufacturers Industry trade journals Systems consultants
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Steps in Evaluating and Purchasing Software Packages
Step 3: evaluate software package alternatives Object is to compare software packages and
select the best alternative Obtain information from many sources
Vendor presentations and literature Product documentation Trade publications Companies that perform software
testing/evaluation Contact users of the package Benchmark test
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Steps in Evaluating and Purchasing Software Packages
Step 4: make the purchase Software licenses Lease agreements Maintenance agreements
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Steps in Evaluating and Purchasing Software PackagesStep 5: install the software package
Installation time depends on size and complexity
Before using the package, complete all implementation steps Loading, configuring, and testing the
software Training users Converting data files to new format
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Hardware Alternatives
Hardware decisions use the same five-step approach as software decisions Evaluate system requirements Identify potential hardware vendors Evaluate hardware alternatives Make the purchase Install the hardware
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Hardware Alternatives
Other issues to consider Turnkey systems Site preparation
New workstations Network cabling Raised floors Conditioned electrical lines Fire extinguishing equipment Uninterruptible power supplies (UPSs)
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TRADEOFF
How do you select the best alternative? Most companies combine
In-house developed software Software packages Outsourcing End-user systems
Object is to develop a list of viable alternatives All viable alternatives must be evaluated Feedback from users is essential
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Completion of Systems Analysis
System requirements document Also called software requirements specification Describes alternatives and makes
recommendation to management Similar to a contract for what will be delivered Must be clear and understandable to users
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Completion of Systems Analysis
Presentation to management Five probable management decisions
1. Develop an in-house system
2. Modify the current system
3. Purchase or customize a software package
4. Perform additional systems analysis work
5. Stop all further work
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Completion of Systems Analysis
Presentation guidelines and suggestions Give overview of the project’s purpose
and objectives Summarize alternatives, with costs, pros,
and cons Explain why the recommended alternative
was chosen Allow time for discussion, questions, and
answers Obtain final decision from management or
timetable for next step
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Prototyping
A prototype is an early, rapidly constructed working version of the system A working model helps users understand the
system Prototyping produces a less-expensive model Can eliminate problems before the final
version
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Prototyping
Prototyping software tools Nonprocedural tools specify the problem to be
solved, rather than how to solve it Fourth-generation environment prototyping
tools CASE toolkit Report writer or report generator
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Prototyping
Fourth-generation environment prototyping tools CASE toolkit Report writer or report generator Query language Screen generator, screen painter, screen
mapper, or form generator Program generator or code generator Fourth-generation language (4GL)
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Prototyping
Prototyping during systems analysis Goal is to develop a working model quickly Early way to test essential system features Prototype can be upgraded or replaced during
later SDLC phases
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Prototyping
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Alternative Graphical Tools
Other tools can be used in addition to DFDs Systems flowcharts State-transition diagrams
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Alternative Graphical Tools
Systems flowcharts Display major process, input, and output
operations Primarily used in physical modeling Various symbols represent data or files in
specific physical media Shape of symbol indicates the purpose Lines with arrowheads indicate the flow of data
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Alternative Graphical Tools
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Alternative Graphical Tools
State-transition diagrams Show time sequence of real-time systems A real-time system processes data and feeds it
back to the system Real-time system examples
Automobile cruise control systems Microprocessor-controlled thermostats Microwave oven control system
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Alternative Graphical Tools
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Transition to Systems Design
Next SDLC phase is system design for in-house system development
Size of the development team depends on the company and the nature of the project
System requirements document An accurate and understandable document is
essential Document contains design for the new system Must reflect thorough analysis and effective
communication