Systems Analysis Requirements Determination Requirements Structuring Alternative Generation and Selection 1 Generate a comprehensive set of alternative design strategies 2 Select t by eza43860

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									      Systems Analysis
 Requirements Determination
 Requirements Structuring
 Alternative Generation and Selection
1. Generate a comprehensive set of alternative
   design strategies
2. Select the one design strategy that is most likely
   to result in the desired information system
         Design Strategy
A particular approach to developing an
Information System. It includes
statements on:
   Functionality
   Hardware and software platform
   Method of acquisition
      Build or buy?
   Software Alternatives
In-house developed software
In-house customization of a package
In-house software developed by contract
personnel
End-user computing
Outsource a customized package
Vendor customizes its package
Vendor enhances its package
Package used with no modification
      Reasons to build
Satisfy unique requirements
Minimize changes in business
procedures and policies
Meet constraints of existing systems
and technology
Develop internal resources and
capabilities
      Reasons to buy
Lower costs and time
Proven reliability and performance
benchmarks
Requires less technical development
staff
Future upgrade provided by the vendor
   Customizing software
Vendor offers individual configurations
for basic packages by adding on
components
Pay the vendor to make enhancements
to meet your individual needs
Buy the package and make your own
modifications
    Outsourcing Contracts
Can provide a cost effective solution for
dealing with rapid technological change
   Time and arrangements
   Fixed price
   Value added
                           ?
            Custom         Packaged     Outsource
            build          system
Business    Unique         Common       Not core to
need                                    the business
In-house    Functional     Functional   Neither
expertise   & technical    only
Project     Desire to      Skills are    Strategic
skills      build skills   not strategic decision
Time        Flexible       Short         Short or
frame                                    Flexible
Application Service Providers
 Application hosting
 Software as service
 Internet is the delivery channel
Evaluating & Purchasing
       Packages
Evaluate the IS requirements
Identify potential vendors
Evaluate alternatives
Make the purchase
Install the package
Evaluate the IS requirements
 Identify the key features of the system
 Estimate volume and future growth
 Specify any hardware constraints
 Prepare a RFP or RFQ
              Software
Horizontal application
Vertical application
   Value added reseller
     Software Vendors
Hardware manufacturers
Packaged software producers
Custom software producers (consulting
firms)
Enterprise solution software
In-house development
         Software Sources
Producers             Capabilities
Hardware              System software and utilities
manufacturers
Packaged software     Supports generic tasks
producers
Custom                Custom support for systems that
software producers    cannot be built internally
Enterprise-wide       Complete systems that cross
solutions             functional boundaries
In-house developers   System built from scratch
      Criteria for Choosing
      Off-the-Shelf Software
Cost
   In-house versus purchased
Functionality
   Mandatory, essential and desired features
Vendor Support
   Installation
   Training
   Technical Support
Viability of Vendor
     Criteria for Choosing
     Off-the-Shelf Software
Flexibility
   Ease of customization
Documentation
   User documentation
   Technical documentation
Response Time
Ease of Installation
Validating Purchased Software
          Information
 Information from vendor
 Software evaluation period
 Customer references from vendor
 Independent software testing service
 Trade publications
  Making the Purchase
Software license
Lease agreement
Maintenance agreement
Installation
   Implementation Issues

Technical and social aspects of
implementation need to be addressed
Training
Disruption of work
           Alternative Matrix
Shop With Me     Web Shop           Shop–N-Go
Developed in C   Developed in C     Developed using
                 and Java           Java
Orders sent to   Can export order   Can save orders
company using information to        in several file
e-mail files     other systems      formats
Easy to          Easy to            Not easily
customize        customize          customized
Widely used by Relatively new       Brand new
other companies application         application
$150 initial fee $700 up-front      $200 annually
Selecting the Best Alternative
       Design Strategy
  Process
     Divide requirements into different sets of
      capabilities
     Enumerate different potential implementation
      environments that could be used to deliver the
      different sets of capabilities
     Propose different ways to source or acquire the
      various sets of capabilities for the different
      implementation environments
Selecting the Best Alternative
       Design Strategy
  Deliverables
  1. At least three substantially different system
     design strategies for building the replacement
     information system
  2. A design strategy judged most likely to lead to
     the most desirable information system
  3. An updated Baseline Project Plan (BPP) for
     turning the most likely design strategy into a
     working information system
Generating Alternative Design
         Strategies
 Best to generate three alternatives
     Low-end
       Provides all required functionality users
        demand with a system that is minimally
        different from the current system
     High-end
       Solves problem in question and provides many
        extra features users desire
     Midrange
       Compromise of features of high-end alternative
        with frugality of low-end alternative
       Drawing Bounds on
       Alternative Designs
Minimum Requirements
   Mandatory features versus desired
    features
   Forms of features
      Data kept in system files
      System outputs
      Analyses to generate outputs
      User expectations on accessibility,response
      time and turnaround time
      Drawing Bounds on
      Alternative Designs
Constraints on System Development
   Time
   Financial and human
   Legal and contractual
   Dynamics of the problem
Hardware and Software Issues
 Existing Platform               New Hardware and
 1. Lower costs                  System Software
 2. Information system staff     1. Some software
    is familiar with operation      components will only run
    and maintenance                 on new platform
 3. Increased odds of            2. Developing system for
    successfully integrating        new platform gives
    system with existing            organization opportunity
    applications                    to upgrade technology
 4. No added costs of               holdings
    converting old systems       3. New requirements may
    to new platform and             allow organization to
    limited data conversion         radically change its
    costs                           computing operations
         Alternative Systems
Requirements        A         B               C

Real-time data      Yes       Yes             Yes
entry
Automatic re-       For some For all items    For all
order decisions     items                     items
Real-time data on   Not       Available for   Fully
inventory levels    available some items      available
         Alternative Systems
Constraints         A          B          C
Development cost    $25,000    $50,000    $65,000
Hardware cost       $25,000    $50,000    $50,000
Time to operation   3 months   6 months   9 months
Ease of training    1 week     2 weeks    1 week
Multi-criteria decision making
 Weighted approach can be used to compare
 the three alternatives
 Decision criteria are the Constraints and
 Requirements
 Weights are arrived at by discussion with
 analysis team, users and managers
 Each requirement and constraint is rated for
 each alternative
     1 indicates that the alternative does not match the
      request well or that it violates the constraint
     5 indicates that the alternative meets or exceeds
      requirements or clearly abides by the constraint
Updating the Baseline Project
        Plan (BPP)
 The Baseline Project Plan (BPP) was
 developed during systems planning and
 selection phase
 Baseline Project Plan (BPP) can be used as
 an outline of a status report at analysis phase
 Schedule will be updated to reflect actual
 activities and durations
 An oral presentation of project status is
 typically made at this phase
Transition to System Design
 Logical Design
    input
    output
    processes
 Physical Design
    system flow charts
    DFDs & ERDs
    CASE Tools
            Physical DFD
Add implementation references
   in parentheses below each component
Draw a human machine boundary
   a line that separates the automated from the
    manual parts of the system
Add system related process and data flows
and stores
   Technical limitations
   Audits, controls or exception handling
Update the data elements in the data flows
   Add system related data elements
Update the metadata in the CASE repository
        Physical ERD
Change entities to tables or files
Change attributes to fields
Add primary keys
Add foreign keys
Add system related components
         Webstore System
          Requirements
Minimum
   Full integration with current systems
   99.9% uptime and availability
Essential
   Flexibility and scalability
Desired
   Technical support and/or emergency response
   Documentation
Webstore System Constraints
 Christmas season rollout
 Small development/support staff
 Transaction-style interaction with
 current systems
 Limited budget for consultants
      Alternative Systems
Outsource ASP (Low-end)
   All hardware located offsite
   Application developed and managed offsite
   Excellent emergency response
   Inflexible
   Difficult to integrate with current systems
      Alternative Systems
ERP system (High-end)
   Stability and documentation
   Required skilled internal staff
   Expensive hardware and software
   Big learning curve
      Alternative Systems
Application server/object framework
(Moderate)
   Excellent integration with current system
   Scalability and flexibility
   Requires internal development and/or
    consultant
   Proprietary
Best Alternative Design Strategy

     Proposed system is a scalable, three-tier
      approach
        Scalable
             The ability to seamlessly upgrade the system through
              either hardware upgrades, software upgrades or both
        Three-tier
            Web Server

                 Provides connection to the Internet and presentation
                  of HTML page
             Applications Server
                 Middle layer of software and hardware that lies
                  between Webserver and corporate network
             Corporate network
                 Existing organizational computing infrastructure

								
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